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-rw-r--r--guides/source/configuring.md319
1 files changed, 212 insertions, 107 deletions
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 28388e4957..66aae112d8 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -35,7 +35,7 @@ In general, the work of configuring Rails means configuring the components of Ra
For example, the `config/application.rb` file includes this setting:
```ruby
-config.autoload_paths += %W(#{config.root}/extras)
+config.time_zone = 'Central Time (US & Canada)'
```
This is a setting for Rails itself. If you want to pass settings to individual Rails components, you can do so via the same `config` object in `config/application.rb`:
@@ -60,11 +60,11 @@ These configuration methods are to be called on a `Rails::Railtie` object, such
* `config.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets, or when you want to work around the concurrency constraints built-in in browsers using different domain aliases. Shorter version of `config.action_controller.asset_host`.
-* `config.autoload_once_paths` accepts an array of paths from which Rails will autoload constants that won't be wiped per request. Relevant if `config.cache_classes` is false, which is the case in development mode by default. Otherwise, all autoloading happens only once. All elements of this array must also be in `autoload_paths`. Default is an empty array.
+* `config.autoload_once_paths` accepts an array of paths from which Rails will autoload constants that won't be wiped per request. Relevant if `config.cache_classes` is `false`, which is the case in development mode by default. Otherwise, all autoloading happens only once. All elements of this array must also be in `autoload_paths`. Default is an empty array.
* `config.autoload_paths` accepts an array of paths from which Rails will autoload constants. Default is all directories under `app`.
-* `config.cache_classes` controls whether or not application classes and modules should be reloaded on each request. Defaults to false in development mode, and true in test and production modes.
+* `config.cache_classes` controls whether or not application classes and modules should be reloaded on each request. Defaults to `false` in development mode, and `true` in test and production modes.
* `config.action_view.cache_template_loading` controls whether or not templates should be reloaded on each request. Defaults to whatever is set for `config.cache_classes`.
@@ -73,9 +73,9 @@ application. Accepts a valid week day symbol (e.g. `:monday`).
* `config.cache_store` configures which cache store to use for Rails caching. Options include one of the symbols `:memory_store`, `:file_store`, `:mem_cache_store`, `:null_store`, or an object that implements the cache API. Defaults to `:file_store` if the directory `tmp/cache` exists, and to `:memory_store` otherwise.
-* `config.colorize_logging` specifies whether or not to use ANSI color codes when logging information. Defaults to true.
+* `config.colorize_logging` specifies whether or not to use ANSI color codes when logging information. Defaults to `true`.
-* `config.consider_all_requests_local` is a flag. If true then any error will cause detailed debugging information to be dumped in the HTTP response, and the `Rails::Info` controller will show the application runtime context in `/rails/info/properties`. True by default in development and test environments, and false in production mode. For finer-grained control, set this to false and implement `local_request?` in controllers to specify which requests should provide debugging information on errors.
+* `config.consider_all_requests_local` is a flag. If `true` then any error will cause detailed debugging information to be dumped in the HTTP response, and the `Rails::Info` controller will show the application runtime context in `/rails/info/properties`. `true` by default in development and test environments, and `false` in production mode. For finer-grained control, set this to `false` and implement `local_request?` in controllers to specify which requests should provide debugging information on errors.
* `config.console` allows you to set class that will be used as console you run `rails console`. It's best to run it in `console` block:
@@ -88,9 +88,9 @@ application. Accepts a valid week day symbol (e.g. `:monday`).
end
```
-* `config.eager_load` when true, eager loads all registered `config.eager_load_namespaces`. This includes your application, engines, Rails frameworks and any other registered namespace.
+* `config.eager_load` when `true`, eager loads all registered `config.eager_load_namespaces`. This includes your application, engines, Rails frameworks and any other registered namespace.
-* `config.eager_load_namespaces` registers namespaces that are eager loaded when `config.eager_load` is true. All namespaces in the list must respond to the `eager_load!` method.
+* `config.eager_load_namespaces` registers namespaces that are eager loaded when `config.eager_load` is `true`. All namespaces in the list must respond to the `eager_load!` method.
* `config.eager_load_paths` accepts an array of paths from which Rails will eager load on boot if cache classes is enabled. Defaults to every folder in the `app` directory of the application.
@@ -98,15 +98,17 @@ application. Accepts a valid week day symbol (e.g. `:monday`).
* `config.exceptions_app` sets the exceptions application invoked by the ShowException middleware when an exception happens. Defaults to `ActionDispatch::PublicExceptions.new(Rails.public_path)`.
-* `config.file_watcher` the class used to detect file updates in the filesystem when `config.reload_classes_only_on_change` is true. Must conform to `ActiveSupport::FileUpdateChecker` API.
+* `config.debug_exception_response_format` sets the format used in responses when errors occur in development mode. Defaults to `:api` for API only apps and `:default` for normal apps.
+
+* `config.file_watcher` is the class used to detect file updates in the file system when `config.reload_classes_only_on_change` is `true`. Rails ships with `ActiveSupport::FileUpdateChecker`, the default, and `ActiveSupport::EventedFileUpdateChecker` (this one depends on the [listen](https://github.com/guard/listen) gem). Custom classes must conform to the `ActiveSupport::FileUpdateChecker` API.
* `config.filter_parameters` used for filtering out the parameters that
you don't want shown in the logs, such as passwords or credit card
-numbers. New applications filter out passwords by adding the following `config.filter_parameters+=[:password]` in `config/initializers/filter_parameter_logging.rb`.
+numbers. By default, Rails filters out passwords by adding `Rails.application.config.filter_parameters += [:password]` in `config/initializers/filter_parameter_logging.rb`. Parameters filter works by partial matching regular expression.
-* `config.force_ssl` forces all requests to be under HTTPS protocol by using `ActionDispatch::SSL` middleware.
+* `config.force_ssl` forces all requests to be served over HTTPS by using the `ActionDispatch::SSL` middleware, and sets `config.action_mailer.default_url_options` to be `{ protocol: 'https' }`. This can be configured by setting `config.ssl_options` - see the [ActionDispatch::SSL documentation](http://edgeapi.rubyonrails.org/classes/ActionDispatch/SSL.html) for details.
-* `config.log_formatter` defines the formatter of the Rails logger. This option defaults to an instance of `ActiveSupport::Logger::SimpleFormatter` for all modes except production, where it defaults to `Logger::Formatter`.
+* `config.log_formatter` defines the formatter of the Rails logger. This option defaults to an instance of `ActiveSupport::Logger::SimpleFormatter` for all modes except production, where it defaults to `Logger::Formatter`. If you are setting a value for `config.logger` you must manually pass the value of your formatter to your logger before it is wrapped in an `ActiveSupport::TaggedLogging` instance, Rails will not do it for you.
* `config.log_level` defines the verbosity of the Rails logger. This option
defaults to `:debug` for all environments. The available log levels are: `:debug`,
@@ -114,15 +116,29 @@ defaults to `:debug` for all environments. The available log levels are: `:debug
* `config.log_tags` accepts a list of: methods that the `request` object responds to, a `Proc` that accepts the `request` object, or something that responds to `to_s`. This makes it easy to tag log lines with debug information like subdomain and request id - both very helpful in debugging multi-user production applications.
-* `config.logger` accepts a logger conforming to the interface of Log4r or the default Ruby `Logger` class. Defaults to an instance of `ActiveSupport::Logger`.
+* `config.logger` is the logger that will be used for `Rails.logger` and any related Rails logging such as `ActiveRecord::Base.logger`. It defaults to an instance of `ActiveSupport::TaggedLogging` that wraps an instance of `ActiveSupport::Logger` which outputs a log to the `log/` directory. You can supply a custom logger, to get full compatibility you must follow these guidelines:
+ * To support a formatter, you must manually assign a formatter from the `config.log_formatter` value to the logger.
+ * To support tagged logs, the log instance must be wrapped with `ActiveSupport::TaggedLogging`.
+ * To support silencing, the logger must include `LoggerSilence` and `ActiveSupport::LoggerThreadSafeLevel` modules. The `ActiveSupport::Logger` class already includes these modules.
+
+ ```ruby
+ class MyLogger < ::Logger
+ include ActiveSupport::LoggerThreadSafeLevel
+ include LoggerSilence
+ end
+
+ mylogger = MyLogger.new(STDOUT)
+ mylogger.formatter = config.log_formatter
+ config.logger = ActiveSupport::TaggedLogging.new(mylogger)
+ ```
* `config.middleware` allows you to configure the application's middleware. This is covered in depth in the [Configuring Middleware](#configuring-middleware) section below.
-* `config.reload_classes_only_on_change` enables or disables reloading of classes only when tracked files change. By default tracks everything on autoload paths and is set to true. If `config.cache_classes` is true, this option is ignored.
+* `config.reload_classes_only_on_change` enables or disables reloading of classes only when tracked files change. By default tracks everything on autoload paths and is set to `true`. If `config.cache_classes` is `true`, this option is ignored.
* `secrets.secret_key_base` is used for specifying a key which allows sessions for the application to be verified against a known secure key to prevent tampering. Applications get `secrets.secret_key_base` initialized to a random key present in `config/secrets.yml`.
-* `config.public_file_server.enabled` configures Rails to serve static files from the public directory. This option defaults to true, but in the production environment it is set to false because the server software (e.g. NGINX or Apache) used to run the application should serve static files instead. If you are running or testing your app in production mode using WEBrick (it is not recommended to use WEBrick in production) set the option to true. Otherwise, you won't be able to use page caching and request for files that exist under the public directory.
+* `config.public_file_server.enabled` configures Rails to serve static files from the public directory. This option defaults to `true`, but in the production environment it is set to `false` because the server software (e.g. NGINX or Apache) used to run the application should serve static files instead. If you are running or testing your app in production mode using WEBrick (it is not recommended to use WEBrick in production) set the option to `true.` Otherwise, you won't be able to use page caching and request for files that exist under the public directory.
* `config.session_store` is usually set up in `config/initializers/session_store.rb` and specifies what class to use to store the session. Possible values are `:cookie_store` which is the default, `:mem_cache_store`, and `:disabled`. The last one tells Rails not to deal with sessions. Custom session stores can also be specified:
@@ -137,16 +153,16 @@ defaults to `:debug` for all environments. The available log levels are: `:debug
### Configuring Assets
* `config.assets.enabled` a flag that controls whether the asset
-pipeline is enabled. It is set to true by default.
+pipeline is enabled. It is set to `true` by default.
* `config.assets.raise_runtime_errors` Set this flag to `true` to enable additional runtime error checking. Recommended in `config/environments/development.rb` to minimize unexpected behavior when deploying to `production`.
-* `config.assets.compress` a flag that enables the compression of compiled assets. It is explicitly set to true in `config/environments/production.rb`.
-
* `config.assets.css_compressor` defines the CSS compressor to use. It is set by default by `sass-rails`. The unique alternative value at the moment is `:yui`, which uses the `yui-compressor` gem.
* `config.assets.js_compressor` defines the JavaScript compressor to use. Possible values are `:closure`, `:uglifier` and `:yui` which require the use of the `closure-compiler`, `uglifier` or `yui-compressor` gems respectively.
+* `config.assets.gzip` a flag that enables the creation of gzipped version of compiled assets, along with non-gzipped assets. Set to `true` by default.
+
* `config.assets.paths` contains the paths which are used to look for assets. Appending paths to this configuration option will cause those paths to be used in the search for assets.
* `config.assets.precompile` allows you to specify additional assets (other than `application.css` and `application.js`) which are to be precompiled when `rake assets:precompile` is run.
@@ -155,15 +171,13 @@ pipeline is enabled. It is set to true by default.
* `config.assets.manifest` defines the full path to be used for the asset precompiler's manifest file. Defaults to a file named `manifest-<random>.json` in the `config.assets.prefix` directory within the public folder.
-* `config.assets.digest` enables the use of MD5 fingerprints in asset names. Set to `true` by default in `production.rb` and `development.rb`.
+* `config.assets.digest` enables the use of MD5 fingerprints in asset names. Set to `true` by default.
* `config.assets.debug` disables the concatenation and compression of assets. Set to `true` by default in `development.rb`.
-* `config.assets.cache_store` defines the cache store that Sprockets will use. The default is the Rails file store.
-
* `config.assets.compile` is a boolean that can be used to turn on live Sprockets compilation in production.
-* `config.assets.logger` accepts a logger conforming to the interface of Log4r or the default Ruby `Logger` class. Defaults to the same configured at `config.logger`. Setting `config.assets.logger` to false will turn off served assets logging.
+* `config.assets.logger` accepts a logger conforming to the interface of Log4r or the default Ruby `Logger` class. Defaults to the same configured at `config.logger`. Setting `config.assets.logger` to `false` will turn off served assets logging.
### Configuring Generators
@@ -191,6 +205,7 @@ The full set of methods that can be used in this block are as follows:
* `scaffold_controller` different from `resource_controller`, defines which generator to use for generating a _scaffolded_ controller when using `rails generate scaffold`. Defaults to `:scaffold_controller`.
* `stylesheets` turns on the hook for stylesheets in generators. Used in Rails for when the `scaffold` generator is run, but this hook can be used in other generates as well. Defaults to `true`.
* `stylesheet_engine` configures the stylesheet engine (for eg. sass) to be used when generating assets. Defaults to `:css`.
+* `scaffold_stylesheet` creates `scaffold.css` when generating a scaffolded resource. Defaults to `true`.
* `test_framework` defines which test framework to use. Defaults to `false` and will use Minitest by default.
* `template_engine` defines which template engine to use, such as ERB or Haml. Defaults to `:erb`.
@@ -198,9 +213,9 @@ The full set of methods that can be used in this block are as follows:
Every Rails application comes with a standard set of middleware which it uses in this order in the development environment:
-* `ActionDispatch::SSL` forces every request to be under HTTPS protocol. Will be available if `config.force_ssl` is set to `true`. Options passed to this can be configured by using `config.ssl_options`.
-* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.public_file_server.enabled` is `false`. Set `config.static_index` if you need to serve a static directory index file that is not named `index`. For example, to serve `main.html` instead of `index.html` for directory requests, set `config.static_index` to `"main"`.
-* `Rack::Lock` wraps the app in mutex so it can only be called by a single thread at a time. Only enabled when `config.cache_classes` is `false`.
+* `ActionDispatch::SSL` forces every request to be served using HTTPS. Enabled if `config.force_ssl` is set to `true`. Options passed to this can be configured by setting `config.ssl_options`.
+* `ActionDispatch::Static` is used to serve static assets. Disabled if `config.public_file_server.enabled` is `false`. Set `config.public_file_server.index_name` if you need to serve a static directory index file that is not named `index`. For example, to serve `main.html` instead of `index.html` for directory requests, set `config.public_file_server.index_name` to `"main"`.
+* `ActionDispatch::Executor` allows thread safe code reloading. Disabled if `config.allow_concurrency` is `false`, which causes `Rack::Lock` to be loaded. `Rack::Lock` wraps the app in mutex so it can only be called by a single thread at a time.
* `ActiveSupport::Cache::Strategy::LocalCache` serves as a basic memory backed cache. This cache is not thread safe and is intended only for serving as a temporary memory cache for a single thread.
* `Rack::Runtime` sets an `X-Runtime` header, containing the time (in seconds) taken to execute the request.
* `Rails::Rack::Logger` notifies the logs that the request has begun. After request is complete, flushes all the logs.
@@ -266,8 +281,8 @@ All these configuration options are delegated to the `I18n` library.
* `config.active_record.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then passed on to any new database connections made. You can retrieve this logger by calling `logger` on either an Active Record model class or an Active Record model instance. Set to `nil` to disable logging.
* `config.active_record.primary_key_prefix_type` lets you adjust the naming for primary key columns. By default, Rails assumes that primary key columns are named `id` (and this configuration option doesn't need to be set.) There are two other choices:
- * `:table_name` would make the primary key for the Customer class `customerid`
- * `:table_name_with_underscore` would make the primary key for the Customer class `customer_id`
+ * `:table_name` would make the primary key for the Customer class `customerid`.
+ * `:table_name_with_underscore` would make the primary key for the Customer class `customer_id`.
* `config.active_record.table_name_prefix` lets you set a global string to be prepended to table names. If you set this to `northwest_`, then the Customer class will look for `northwest_customers` as its table. The default is an empty string.
@@ -275,15 +290,17 @@ All these configuration options are delegated to the `I18n` library.
* `config.active_record.schema_migrations_table_name` lets you set a string to be used as the name of the schema migrations table.
-* `config.active_record.pluralize_table_names` specifies whether Rails will look for singular or plural table names in the database. If set to true (the default), then the Customer class will use the `customers` table. If set to false, then the Customer class will use the `customer` table.
+* `config.active_record.pluralize_table_names` specifies whether Rails will look for singular or plural table names in the database. If set to `true` (the default), then the Customer class will use the `customers` table. If set to false, then the Customer class will use the `customer` table.
* `config.active_record.default_timezone` determines whether to use `Time.local` (if set to `:local`) or `Time.utc` (if set to `:utc`) when pulling dates and times from the database. The default is `:utc`.
* `config.active_record.schema_format` controls the format for dumping the database schema to a file. The options are `:ruby` (the default) for a database-independent version that depends on migrations, or `:sql` for a set of (potentially database-dependent) SQL statements.
-* `config.active_record.timestamped_migrations` controls whether migrations are numbered with serial integers or with timestamps. The default is true, to use timestamps, which are preferred if there are multiple developers working on the same application.
+* `config.active_record.error_on_ignored_order_or_limit` specifies if an error should be raised if the order or limit of a query is ignored during a batch query. The options are `true` (raise error) or `false` (warn). Default is `false`.
-* `config.active_record.lock_optimistically` controls whether Active Record will use optimistic locking and is true by default.
+* `config.active_record.timestamped_migrations` controls whether migrations are numbered with serial integers or with timestamps. The default is `true`, to use timestamps, which are preferred if there are multiple developers working on the same application.
+
+* `config.active_record.lock_optimistically` controls whether Active Record will use optimistic locking and is `true` by default.
* `config.active_record.cache_timestamp_format` controls the format of the timestamp value in the cache key. Default is `:nsec`.
@@ -291,13 +308,13 @@ All these configuration options are delegated to the `I18n` library.
* `config.active_record.partial_writes` is a boolean value and controls whether or not partial writes are used (i.e. whether updates only set attributes that are dirty). Note that when using partial writes, you should also use optimistic locking `config.active_record.lock_optimistically` since concurrent updates may write attributes based on a possibly stale read state. The default value is `true`.
-* `config.active_record.maintain_test_schema` is a boolean value which controls whether Active Record should try to keep your test database schema up-to-date with `db/schema.rb` (or `db/structure.sql`) when you run your tests. The default is true.
+* `config.active_record.maintain_test_schema` is a boolean value which controls whether Active Record should try to keep your test database schema up-to-date with `db/schema.rb` (or `db/structure.sql`) when you run your tests. The default is `true`.
* `config.active_record.dump_schema_after_migration` is a flag which
controls whether or not schema dump should happen (`db/schema.rb` or
- `db/structure.sql`) when you run migrations. This is set to false in
+ `db/structure.sql`) when you run migrations. This is set to `false` in
`config/environments/production.rb` which is generated by Rails. The
- default value is true if this configuration is not set.
+ default value is `true` if this configuration is not set.
* `config.active_record.dump_schemas` controls which database schemas will be dumped when calling db:structure:dump.
The options are `:schema_search_path` (the default) which dumps any schemas listed in schema_search_path,
@@ -315,11 +332,11 @@ All these configuration options are delegated to the `I18n` library.
* `config.active_record.index_nested_attribute_errors` allows errors for nested
has_many relationships to be displayed with an index as well as the error.
- Defaults to false.
+ Defaults to `false`.
The MySQL adapter adds one additional configuration option:
-* `ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns in a MySQL database to be booleans and is true by default.
+* `ActiveRecord::ConnectionAdapters::Mysql2Adapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns as booleans. Defaults to `true`.
The schema dumper adds one additional configuration option:
@@ -331,13 +348,11 @@ The schema dumper adds one additional configuration option:
* `config.action_controller.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets rather than the application server itself.
-* `config.action_controller.perform_caching` configures whether the application should perform the caching features provided by the Action Controller component or not. Set to false in development mode, true in production.
+* `config.action_controller.perform_caching` configures whether the application should perform the caching features provided by the Action Controller component or not. Set to `false` in development mode, `true` in production.
* `config.action_controller.default_static_extension` configures the extension used for cached pages. Defaults to `.html`.
-* `config.action_controller.default_charset` specifies the default character set for all renders. The default is "utf-8".
-
-* `config.action_controller.include_all_helpers` configures whether all view helpers are available everywhere or are scoped to the corresponding controller. If set to `false`, `UsersHelper` methods are only available for views rendered as part of `UsersController`. If `true`, `UsersHelper` methods are available everywhere. The default is `true`.
+* `config.action_controller.include_all_helpers` configures whether all view helpers are available everywhere or are scoped to the corresponding controller. If set to `false`, `UsersHelper` methods are only available for views rendered as part of `UsersController`. If `true`, `UsersHelper` methods are available everywhere. The default configuration behavior (when this option is not explicitly set to `true` or `false`) is that all view helpers are available to each controller.
* `config.action_controller.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Action Controller. Set to `nil` to disable logging.
@@ -345,6 +360,10 @@ The schema dumper adds one additional configuration option:
* `config.action_controller.allow_forgery_protection` enables or disables CSRF protection. By default this is `false` in test mode and `true` in all other modes.
+* `config.action_controller.forgery_protection_origin_check` configures whether the HTTP `Origin` header should be checked against the site's origin as an additional CSRF defense.
+
+* `config.action_controller.per_form_csrf_tokens` configures whether CSRF tokens are only valid for the method/action they were generated for.
+
* `config.action_controller.relative_url_root` can be used to tell Rails that you are [deploying to a subdirectory](configuring.html#deploy-to-a-subdirectory-relative-url-root). The default is `ENV['RAILS_RELATIVE_URL_ROOT']`.
* `config.action_controller.permit_all_parameters` sets all the parameters for mass assignment to be permitted by default. The default value is `false`.
@@ -367,8 +386,14 @@ The schema dumper adds one additional configuration option:
}
```
+* `config.action_dispatch.default_charset` specifies the default character set for all renders. Defaults to `nil`.
+
* `config.action_dispatch.tld_length` sets the TLD (top-level domain) length for the application. Defaults to `1`.
+* `config.action_dispatch.ignore_accept_header` is used to determine whether to ignore accept headers from a request. Defaults to `false`.
+
+* `config.action_dispatch.x_sendfile_header` specifies server specific X-Sendfile header. This is useful for accelerated file sending from server. For example it can be set to 'X-Sendfile' for Apache.
+
* `config.action_dispatch.http_auth_salt` sets the HTTP Auth salt value. Defaults
to `'http authentication'`.
@@ -383,7 +408,7 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
* `config.action_dispatch.perform_deep_munge` configures whether `deep_munge`
method should be performed on the parameters. See [Security Guide](security.html#unsafe-query-generation)
- for more information. It defaults to true.
+ for more information. It defaults to `true`.
* `config.action_dispatch.rescue_responses` configures what exceptions are assigned to an HTTP status. It accepts a hash and you can specify pairs of exception/status. By default, this is defined as:
@@ -438,7 +463,7 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
* `config.action_view.embed_authenticity_token_in_remote_forms` allows you to
set the default behavior for `authenticity_token` in forms with `remote:
- true`. By default it's set to false, which means that remote forms will not
+ true`. By default it's set to `false`, which means that remote forms will not
include `authenticity_token`, which is helpful when you're fragment-caching
the form. Remote forms get the authenticity from the `meta` tag, so embedding
is unnecessary unless you support browsers without JavaScript. In such case
@@ -457,7 +482,9 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
error should be raised for missing translations.
* `config.action_view.automatically_disable_submit_tag` determines whether
- submit_tag should automatically disable on click, this defaults to true.
+ submit_tag should automatically disable on click, this defaults to `true`.
+
+* `config.action_view.debug_missing_translation` determines whether to wrap the missing translations key in a `<span>` tag or not. This defaults to `true`.
### Configuring Action Mailer
@@ -472,16 +499,19 @@ There are a number of settings available on `config.action_mailer`:
* `:user_name` - If your mail server requires authentication, set the username in this setting.
* `:password` - If your mail server requires authentication, set the password in this setting.
* `:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain`, `:login`, `:cram_md5`.
+ * `:enable_starttls_auto` - Detects if STARTTLS is enabled in your SMTP server and starts to use it. It defaults to `true`.
+ * `:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is useful if you need to validate a self-signed and/or a wildcard certificate. This can be one of the OpenSSL verify constants, `:none`, `:peer`, `:client_once`, `:fail_if_no_peer_cert`, or the constant directly `OpenSSL::SSL::VERIFY_NONE`.
+ * `:ssl/:tls` - Enables the SMTP connection to use SMTP/TLS (SMTPS: SMTP over direct TLS connection).
* `config.action_mailer.sendmail_settings` allows detailed configuration for the `sendmail` delivery method. It accepts a hash of options, which can include any of these options:
* `:location` - The location of the sendmail executable. Defaults to `/usr/sbin/sendmail`.
* `:arguments` - The command line arguments. Defaults to `-i -t`.
-* `config.action_mailer.raise_delivery_errors` specifies whether to raise an error if email delivery cannot be completed. It defaults to true.
+* `config.action_mailer.raise_delivery_errors` specifies whether to raise an error if email delivery cannot be completed. It defaults to `true`.
-* `config.action_mailer.delivery_method` defines the delivery method and defaults to `:smtp`. See the [configuration section in the Action Mailer guide](http://guides.rubyonrails.org/action_mailer_basics.html#action-mailer-configuration) for more info.
+* `config.action_mailer.delivery_method` defines the delivery method and defaults to `:smtp`. See the [configuration section in the Action Mailer guide](action_mailer_basics.html#action-mailer-configuration) for more info.
-* `config.action_mailer.perform_deliveries` specifies whether mail will actually be delivered and is true by default. It can be convenient to set it to false for testing.
+* `config.action_mailer.perform_deliveries` specifies whether mail will actually be delivered and is true by default. It can be convenient to set it to `false` for testing.
* `config.action_mailer.default_options` configures Action Mailer defaults. Use to set options like `from` or `reply_to` for every mailer. These default to:
@@ -527,6 +557,9 @@ There are a number of settings available on `config.action_mailer`:
* `config.action_mailer.deliver_later_queue_name` specifies the queue name for
mailers. By default this is `mailers`.
+* `config.action_mailer.perform_caching` specifies whether the mailer templates should perform fragment caching or not. By default this is `false` in all environments.
+
+
### Configuring Active Support
There are a few configuration options available in Active Support:
@@ -541,7 +574,7 @@ There are a few configuration options available in Active Support:
* `config.active_support.time_precision` sets the precision of JSON encoded time values. Defaults to `3`.
-* `ActiveSupport.halt_callback_chains_on_return_false` specifies whether Active Record and Active Model callback chains can be halted by returning `false` in a 'before' callback. Defaults to `true`.
+* `ActiveSupport.halt_callback_chains_on_return_false` specifies whether Active Record and Active Model callback chains can be halted by returning `false` in a 'before' callback. When set to `false`, callback chains are halted only when explicitly done so with `throw(:abort)`. When set to `true`, callback chains are halted when a callback returns `false` (the previous behavior before Rails 5) and a deprecation warning is given. Defaults to `true` during the deprecation period. New Rails 5 apps generate an initializer file called `callback_terminator.rb` which sets the value to `false`. This file is *not* added when running `rails app:update`, so returning `false` will still work on older apps ported to Rails 5 and display a deprecation warning to prompt users to update their code.
* `ActiveSupport::Logger.silencer` is set to `false` to disable the ability to silence logging in a block. The default is `true`.
@@ -557,7 +590,7 @@ There are a few configuration options available in Active Support:
`config.active_job` provides the following configuration options:
-* `config.active_job.queue_adapter` sets the adapter for the queueing backend. The default adapter is `:inline` which will perform jobs immediately. For an up-to-date list of built-in adapters see the [ActiveJob::QueueAdapters API documentation](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).
+* `config.active_job.queue_adapter` sets the adapter for the queueing backend. The default adapter is `:async`. For an up-to-date list of built-in adapters see the [ActiveJob::QueueAdapters API documentation](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).
```ruby
# Be sure to have the adapter's gem in your Gemfile
@@ -606,6 +639,17 @@ There are a few configuration options available in Active Support:
* `config.active_job.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Active Job. You can retrieve this logger by calling `logger` on either an Active Job class or an Active Job instance. Set to `nil` to disable logging.
+### Configuring Action Cable
+
+* `config.action_cable.url` accepts a string for the URL for where
+ you are hosting your Action Cable server. You would use this option
+if you are running Action Cable servers that are separated from your
+main application.
+* `config.action_cable.mount_path` accepts a string for where to mount Action
+ Cable, as part of the main server process. Defaults to `/cable`.
+You can set this as nil to not mount Action Cable as part of your
+normal Rails server.
+
### Configuring a Database
Just about every Rails application will interact with a database. You can connect to the database by setting an environment variable `ENV['DATABASE_URL']` or by using a configuration file called `config/database.yml`.
@@ -747,11 +791,11 @@ development:
timeout: 5000
```
-NOTE: Rails uses an SQLite3 database for data storage by default because it is a zero configuration database that just works. Rails also supports MySQL and PostgreSQL "out of the box", and has plugins for many database systems. If you are using a database in a production environment Rails most likely has an adapter for it.
+NOTE: Rails uses an SQLite3 database for data storage by default because it is a zero configuration database that just works. Rails also supports MySQL (including MariaDB) and PostgreSQL "out of the box", and has plugins for many database systems. If you are using a database in a production environment Rails most likely has an adapter for it.
-#### Configuring a MySQL Database
+#### Configuring a MySQL or MariaDB Database
-If you choose to use MySQL instead of the shipped SQLite3 database, your `config/database.yml` will look a little different. Here's the development section:
+If you choose to use MySQL or MariaDB instead of the shipped SQLite3 database, your `config/database.yml` will look a little different. Here's the development section:
```yaml
development:
@@ -764,7 +808,7 @@ development:
socket: /tmp/mysql.sock
```
-If your development computer's MySQL installation includes a root user with an empty password, this configuration should work for you. Otherwise, change the username and password in the `development` section as appropriate.
+If your development database has a root user with an empty password, this configuration should work for you. Otherwise, change the username and password in the `development` section as appropriate.
#### Configuring a PostgreSQL Database
@@ -806,9 +850,9 @@ development:
database: db/development.sqlite3
```
-#### Configuring a MySQL Database for JRuby Platform
+#### Configuring a MySQL or MariaDB Database for JRuby Platform
-If you choose to use MySQL and are using JRuby, your `config/database.yml` will look a little different. Here's the development section:
+If you choose to use MySQL or MariaDB and are using JRuby, your `config/database.yml` will look a little different. Here's the development section:
```yaml
development:
@@ -861,7 +905,7 @@ Rails will now prepend "/app1" when generating links.
#### Using Passenger
-Passenger makes it easy to run your application in a subdirectory. You can find the relevant configuration in the [Passenger manual](http://www.modrails.com/documentation/Users%20guide%20Apache.html#deploying_rails_to_sub_uri).
+Passenger makes it easy to run your application in a subdirectory. You can find the relevant configuration in the [Passenger manual](https://www.phusionpassenger.com/library/deploy/apache/deploy/ruby/#deploying-an-app-to-a-sub-uri-or-subdirectory).
#### Using a Reverse Proxy
@@ -986,98 +1030,110 @@ Because `Rails::Application` inherits from `Rails::Railtie` (indirectly), you ca
Below is a comprehensive list of all the initializers found in Rails in the order that they are defined (and therefore run in, unless otherwise stated).
-* `load_environment_hook` Serves as a placeholder so that `:load_environment_config` can be defined to run before it.
+* `load_environment_hook`: Serves as a placeholder so that `:load_environment_config` can be defined to run before it.
+
+* `load_active_support`: Requires `active_support/dependencies` which sets up the basis for Active Support. Optionally requires `active_support/all` if `config.active_support.bare` is un-truthful, which is the default.
+
+* `initialize_logger`: Initializes the logger (an `ActiveSupport::Logger` object) for the application and makes it accessible at `Rails.logger`, provided that no initializer inserted before this point has defined `Rails.logger`.
-* `load_active_support` Requires `active_support/dependencies` which sets up the basis for Active Support. Optionally requires `active_support/all` if `config.active_support.bare` is un-truthful, which is the default.
+* `initialize_cache`: If `Rails.cache` isn't set yet, initializes the cache by referencing the value in `config.cache_store` and stores the outcome as `Rails.cache`. If this object responds to the `middleware` method, its middleware is inserted before `Rack::Runtime` in the middleware stack.
-* `initialize_logger` Initializes the logger (an `ActiveSupport::Logger` object) for the application and makes it accessible at `Rails.logger`, provided that no initializer inserted before this point has defined `Rails.logger`.
+* `set_clear_dependencies_hook`: This initializer - which runs only if `cache_classes` is set to `false` - uses `ActionDispatch::Callbacks.after` to remove the constants which have been referenced during the request from the object space so that they will be reloaded during the following request.
-* `initialize_cache` If `Rails.cache` isn't set yet, initializes the cache by referencing the value in `config.cache_store` and stores the outcome as `Rails.cache`. If this object responds to the `middleware` method, its middleware is inserted before `Rack::Runtime` in the middleware stack.
+* `initialize_dependency_mechanism`: If `config.cache_classes` is true, configures `ActiveSupport::Dependencies.mechanism` to `require` dependencies rather than `load` them.
-* `set_clear_dependencies_hook` Provides a hook for `active_record.set_dispatch_hooks` to use, which will run before this initializer. This initializer - which runs only if `cache_classes` is set to `false` - uses `ActionDispatch::Callbacks.after` to remove the constants which have been referenced during the request from the object space so that they will be reloaded during the following request.
+* `bootstrap_hook`: Runs all configured `before_initialize` blocks.
-* `initialize_dependency_mechanism` If `config.cache_classes` is true, configures `ActiveSupport::Dependencies.mechanism` to `require` dependencies rather than `load` them.
+* `i18n.callbacks`: In the development environment, sets up a `to_prepare` callback which will call `I18n.reload!` if any of the locales have changed since the last request. In production mode this callback will only run on the first request.
-* `bootstrap_hook` Runs all configured `before_initialize` blocks.
+* `active_support.deprecation_behavior`: Sets up deprecation reporting for environments, defaulting to `:log` for development, `:notify` for production and `:stderr` for test. If a value isn't set for `config.active_support.deprecation` then this initializer will prompt the user to configure this line in the current environment's `config/environments` file. Can be set to an array of values.
-* `i18n.callbacks` In the development environment, sets up a `to_prepare` callback which will call `I18n.reload!` if any of the locales have changed since the last request. In production mode this callback will only run on the first request.
+* `active_support.initialize_time_zone`: Sets the default time zone for the application based on the `config.time_zone` setting, which defaults to "UTC".
-* `active_support.deprecation_behavior` Sets up deprecation reporting for environments, defaulting to `:log` for development, `:notify` for production and `:stderr` for test. If a value isn't set for `config.active_support.deprecation` then this initializer will prompt the user to configure this line in the current environment's `config/environments` file. Can be set to an array of values.
+* `active_support.initialize_beginning_of_week`: Sets the default beginning of week for the application based on `config.beginning_of_week` setting, which defaults to `:monday`.
-* `active_support.initialize_time_zone` Sets the default time zone for the application based on the `config.time_zone` setting, which defaults to "UTC".
+* `active_support.set_configs`: Sets up Active Support by using the settings in `config.active_support` by `send`'ing the method names as setters to `ActiveSupport` and passing the values through.
-* `active_support.initialize_beginning_of_week` Sets the default beginning of week for the application based on `config.beginning_of_week` setting, which defaults to `:monday`.
+* `action_dispatch.configure`: Configures the `ActionDispatch::Http::URL.tld_length` to be set to the value of `config.action_dispatch.tld_length`.
-* `action_dispatch.configure` Configures the `ActionDispatch::Http::URL.tld_length` to be set to the value of `config.action_dispatch.tld_length`.
+* `action_view.set_configs`: Sets up Action View by using the settings in `config.action_view` by `send`'ing the method names as setters to `ActionView::Base` and passing the values through.
-* `action_view.set_configs` Sets up Action View by using the settings in `config.action_view` by `send`'ing the method names as setters to `ActionView::Base` and passing the values through.
+* `action_controller.assets_config`: Initializes the `config.actions_controller.assets_dir` to the app's public directory if not explicitly configured.
-* `action_controller.logger` Sets `ActionController::Base.logger` - if it's not already set - to `Rails.logger`.
+* `action_controller.set_helpers_path`: Sets Action Controller's `helpers_path` to the application's `helpers_path`.
-* `action_controller.initialize_framework_caches` Sets `ActionController::Base.cache_store` - if it's not already set - to `Rails.cache`.
+* `action_controller.parameters_config`: Configures strong parameters options for `ActionController::Parameters`.
-* `action_controller.set_configs` Sets up Action Controller by using the settings in `config.action_controller` by `send`'ing the method names as setters to `ActionController::Base` and passing the values through.
+* `action_controller.set_configs`: Sets up Action Controller by using the settings in `config.action_controller` by `send`'ing the method names as setters to `ActionController::Base` and passing the values through.
-* `action_controller.compile_config_methods` Initializes methods for the config settings specified so that they are quicker to access.
+* `action_controller.compile_config_methods`: Initializes methods for the config settings specified so that they are quicker to access.
-* `active_record.initialize_timezone` Sets `ActiveRecord::Base.time_zone_aware_attributes` to true, as well as setting `ActiveRecord::Base.default_timezone` to UTC. When attributes are read from the database, they will be converted into the time zone specified by `Time.zone`.
+* `active_record.initialize_timezone`: Sets `ActiveRecord::Base.time_zone_aware_attributes` to `true`, as well as setting `ActiveRecord::Base.default_timezone` to UTC. When attributes are read from the database, they will be converted into the time zone specified by `Time.zone`.
-* `active_record.logger` Sets `ActiveRecord::Base.logger` - if it's not already set - to `Rails.logger`.
+* `active_record.logger`: Sets `ActiveRecord::Base.logger` - if it's not already set - to `Rails.logger`.
-* `active_record.set_configs` Sets up Active Record by using the settings in `config.active_record` by `send`'ing the method names as setters to `ActiveRecord::Base` and passing the values through.
+* `active_record.migration_error`: Configures middleware to check for pending migrations.
-* `active_record.initialize_database` Loads the database configuration (by default) from `config/database.yml` and establishes a connection for the current environment.
+* `active_record.check_schema_cache_dump`: Loads the schema cache dump if configured and available.
-* `active_record.log_runtime` Includes `ActiveRecord::Railties::ControllerRuntime` which is responsible for reporting the time taken by Active Record calls for the request back to the logger.
+* `active_record.warn_on_records_fetched_greater_than`: Enables warnings when queries return large numbers of records.
-* `active_record.set_dispatch_hooks` Resets all reloadable connections to the database if `config.cache_classes` is set to `false`.
+* `active_record.set_configs`: Sets up Active Record by using the settings in `config.active_record` by `send`'ing the method names as setters to `ActiveRecord::Base` and passing the values through.
-* `active_job.logger` Sets `ActiveJob::Base.logger` - if it's not already set -
+* `active_record.initialize_database`: Loads the database configuration (by default) from `config/database.yml` and establishes a connection for the current environment.
+
+* `active_record.log_runtime`: Includes `ActiveRecord::Railties::ControllerRuntime` which is responsible for reporting the time taken by Active Record calls for the request back to the logger.
+
+* `active_record.set_reloader_hooks`: Resets all reloadable connections to the database if `config.cache_classes` is set to `false`.
+
+* `active_record.add_watchable_files`: Adds `schema.rb` and `structure.sql` files to watchable files.
+
+* `active_job.logger`: Sets `ActiveJob::Base.logger` - if it's not already set -
to `Rails.logger`.
-* `active_job.set_configs` Sets up Active Job by using the settings in `config.active_job` by `send`'ing the method names as setters to `ActiveJob::Base` and passing the values through.
+* `active_job.set_configs`: Sets up Active Job by using the settings in `config.active_job` by `send`'ing the method names as setters to `ActiveJob::Base` and passing the values through.
-* `action_mailer.logger` Sets `ActionMailer::Base.logger` - if it's not already set - to `Rails.logger`.
+* `action_mailer.logger`: Sets `ActionMailer::Base.logger` - if it's not already set - to `Rails.logger`.
-* `action_mailer.set_configs` Sets up Action Mailer by using the settings in `config.action_mailer` by `send`'ing the method names as setters to `ActionMailer::Base` and passing the values through.
+* `action_mailer.set_configs`: Sets up Action Mailer by using the settings in `config.action_mailer` by `send`'ing the method names as setters to `ActionMailer::Base` and passing the values through.
-* `action_mailer.compile_config_methods` Initializes methods for the config settings specified so that they are quicker to access.
+* `action_mailer.compile_config_methods`: Initializes methods for the config settings specified so that they are quicker to access.
-* `set_load_path` This initializer runs before `bootstrap_hook`. Adds the `vendor`, `lib`, all directories of `app` and any paths specified by `config.load_paths` to `$LOAD_PATH`.
+* `set_load_path`: This initializer runs before `bootstrap_hook`. Adds paths specified by `config.load_paths` and all autoload paths to `$LOAD_PATH`.
-* `set_autoload_paths` This initializer runs before `bootstrap_hook`. Adds all sub-directories of `app` and paths specified by `config.autoload_paths` to `ActiveSupport::Dependencies.autoload_paths`.
+* `set_autoload_paths`: This initializer runs before `bootstrap_hook`. Adds all sub-directories of `app` and paths specified by `config.autoload_paths`, `config.eager_load_paths` and `config.autoload_once_paths` to `ActiveSupport::Dependencies.autoload_paths`.
-* `add_routing_paths` Loads (by default) all `config/routes.rb` files (in the application and railties, including engines) and sets up the routes for the application.
+* `add_routing_paths`: Loads (by default) all `config/routes.rb` files (in the application and railties, including engines) and sets up the routes for the application.
-* `add_locales` Adds the files in `config/locales` (from the application, railties and engines) to `I18n.load_path`, making available the translations in these files.
+* `add_locales`: Adds the files in `config/locales` (from the application, railties and engines) to `I18n.load_path`, making available the translations in these files.
-* `add_view_paths` Adds the directory `app/views` from the application, railties and engines to the lookup path for view files for the application.
+* `add_view_paths`: Adds the directory `app/views` from the application, railties and engines to the lookup path for view files for the application.
-* `load_environment_config` Loads the `config/environments` file for the current environment.
+* `load_environment_config`: Loads the `config/environments` file for the current environment.
-* `prepend_helpers_path` Adds the directory `app/helpers` from the application, railties and engines to the lookup path for helpers for the application.
+* `prepend_helpers_path`: Adds the directory `app/helpers` from the application, railties and engines to the lookup path for helpers for the application.
-* `load_config_initializers` Loads all Ruby files from `config/initializers` in the application, railties and engines. The files in this directory can be used to hold configuration settings that should be made after all of the frameworks are loaded.
+* `load_config_initializers`: Loads all Ruby files from `config/initializers` in the application, railties and engines. The files in this directory can be used to hold configuration settings that should be made after all of the frameworks are loaded.
-* `engines_blank_point` Provides a point-in-initialization to hook into if you wish to do anything before engines are loaded. After this point, all railtie and engine initializers are run.
+* `engines_blank_point`: Provides a point-in-initialization to hook into if you wish to do anything before engines are loaded. After this point, all railtie and engine initializers are run.
-* `add_generator_templates` Finds templates for generators at `lib/templates` for the application, railties and engines and adds these to the `config.generators.templates` setting, which will make the templates available for all generators to reference.
+* `add_generator_templates`: Finds templates for generators at `lib/templates` for the application, railties and engines and adds these to the `config.generators.templates` setting, which will make the templates available for all generators to reference.
-* `ensure_autoload_once_paths_as_subset` Ensures that the `config.autoload_once_paths` only contains paths from `config.autoload_paths`. If it contains extra paths, then an exception will be raised.
+* `ensure_autoload_once_paths_as_subset`: Ensures that the `config.autoload_once_paths` only contains paths from `config.autoload_paths`. If it contains extra paths, then an exception will be raised.
-* `add_to_prepare_blocks` The block for every `config.to_prepare` call in the application, a railtie or engine is added to the `to_prepare` callbacks for Action Dispatch which will be run per request in development, or before the first request in production.
+* `add_to_prepare_blocks`: The block for every `config.to_prepare` call in the application, a railtie or engine is added to the `to_prepare` callbacks for Action Dispatch which will be run per request in development, or before the first request in production.
-* `add_builtin_route` If the application is running under the development environment then this will append the route for `rails/info/properties` to the application routes. This route provides the detailed information such as Rails and Ruby version for `public/index.html` in a default Rails application.
+* `add_builtin_route`: If the application is running under the development environment then this will append the route for `rails/info/properties` to the application routes. This route provides the detailed information such as Rails and Ruby version for `public/index.html` in a default Rails application.
-* `build_middleware_stack` Builds the middleware stack for the application, returning an object which has a `call` method which takes a Rack environment object for the request.
+* `build_middleware_stack`: Builds the middleware stack for the application, returning an object which has a `call` method which takes a Rack environment object for the request.
-* `eager_load!` If `config.eager_load` is true, runs the `config.before_eager_load` hooks and then calls `eager_load!` which will load all `config.eager_load_namespaces`.
+* `eager_load!`: If `config.eager_load` is `true`, runs the `config.before_eager_load` hooks and then calls `eager_load!` which will load all `config.eager_load_namespaces`.
-* `finisher_hook` Provides a hook for after the initialization of process of the application is complete, as well as running all the `config.after_initialize` blocks for the application, railties and engines.
+* `finisher_hook`: Provides a hook for after the initialization of process of the application is complete, as well as running all the `config.after_initialize` blocks for the application, railties and engines.
-* `set_routes_reloader` Configures Action Dispatch to reload the routes file using `ActionDispatch::Callbacks.to_prepare`.
+* `set_routes_reloader`: Configures Action Dispatch to reload the routes file using `ActionDispatch::Callbacks.to_prepare`.
-* `disable_dependency_loading` Disables the automatic dependency loading if the `config.eager_load` is set to true.
+* `disable_dependency_loading`: Disables the automatic dependency loading if the `config.eager_load` is set to `true`.
Database pooling
----------------
@@ -1113,21 +1169,48 @@ NOTE. If you are running in a multi-threaded environment, there could be a chanc
Custom configuration
--------------------
-You can configure your own code through the Rails configuration object with custom configuration under the `config.x` property. It works like this:
+You can configure your own code through the Rails configuration object with custom configuration. It works like this:
```ruby
- config.x.payment_processing.schedule = :daily
- config.x.payment_processing.retries = 3
- config.x.super_debugger = true
+ config.payment_processing.schedule = :daily
+ config.payment_processing.retries = 3
+ config.super_debugger = true
```
These configuration points are then available through the configuration object:
```ruby
- Rails.configuration.x.payment_processing.schedule # => :daily
- Rails.configuration.x.payment_processing.retries # => 3
- Rails.configuration.x.super_debugger # => true
- Rails.configuration.x.super_debugger.not_set # => nil
+ Rails.configuration.payment_processing.schedule # => :daily
+ Rails.configuration.payment_processing.retries # => 3
+ Rails.configuration.super_debugger # => true
+ Rails.configuration.super_debugger.not_set # => nil
+ ```
+
+You can also use `Rails::Application.config_for` to load whole configuration files:
+
+ ```ruby
+ # config/payment.yml:
+ production:
+ environment: production
+ merchant_id: production_merchant_id
+ public_key: production_public_key
+ private_key: production_private_key
+ development:
+ environment: sandbox
+ merchant_id: development_merchant_id
+ public_key: development_public_key
+ private_key: development_private_key
+
+ # config/application.rb
+ module MyApp
+ class Application < Rails::Application
+ config.payment = config_for(:payment)
+ end
+ end
+ ```
+
+ ```ruby
+ Rails.configuration.payment['merchant_id'] # => production_merchant_id or development_merchant_id
```
Search Engines Indexing
@@ -1149,3 +1232,25 @@ Disallow: /
To block just specific pages, it's necessary to use a more complex syntax. Learn
it on the [official documentation](http://www.robotstxt.org/robotstxt.html).
+
+Evented File System Monitor
+---------------------------
+
+If the [listen gem](https://github.com/guard/listen) is loaded Rails uses an
+evented file system monitor to detect changes when `config.cache_classes` is
+`false`:
+
+```ruby
+group :development do
+ gem 'listen', '~> 3.0.4'
+end
+```
+
+Otherwise, in every request Rails walks the application tree to check if
+anything has changed.
+
+On Linux and Mac OS X no additional gems are needed, but some are required
+[for *BSD](https://github.com/guard/listen#on-bsd) and
+[for Windows](https://github.com/guard/listen#on-windows).
+
+Note that [some setups are unsupported](https://github.com/guard/listen#issues--limitations).