diff options
Diffstat (limited to 'guides/source')
| -rw-r--r-- | guides/source/4_2_release_notes.md | 5 | ||||
| -rw-r--r-- | guides/source/active_record_validations.md | 2 | ||||
| -rw-r--r-- | guides/source/caching_with_rails.md | 22 | ||||
| -rw-r--r-- | guides/source/debugging_rails_applications.md | 85 | ||||
| -rw-r--r-- | guides/source/upgrading_ruby_on_rails.md | 14 |
5 files changed, 68 insertions, 60 deletions
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md index d5b3766a5b..684bd286bc 100644 --- a/guides/source/4_2_release_notes.md +++ b/guides/source/4_2_release_notes.md @@ -214,8 +214,9 @@ end Due to a [change in Rack](https://github.com/rack/rack/commit/28b014484a8ac0bbb388e7eaeeef159598ec64fc), `rails server` now listens on `localhost` instead of `0.0.0.0` by default. This -should have minimal impact on the standard development workflow as http://localhost:3000 -will continue to work as before on your own machine. +should have minimal impact on the standard development workflow as both +http://127.0.0.1:3000 and http://localhost:3000 will continue to work as before +on your own machine. However, with this change you will no longer be able to access the Rails server from a different machine, for example if your development environment diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md index d251c5c0b1..343b761e93 100644 --- a/guides/source/active_record_validations.md +++ b/guides/source/active_record_validations.md @@ -617,7 +617,7 @@ end The validation happens by performing an SQL query into the model's table, searching for an existing record with the same value in that attribute. -There is a `:scope` option that you can use to specify other attributes that +There is a `:scope` option that you can use to specify one or more attributes that are used to limit the uniqueness check: ```ruby diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md index 716beb9178..782406659d 100644 --- a/guides/source/caching_with_rails.md +++ b/guides/source/caching_with_rails.md @@ -22,7 +22,7 @@ fragment caching. Rails provides by default fragment caching. In order to use page and action caching, you will need to add `actionpack-page_caching` and `actionpack-action_caching` to your Gemfile. -To start playing with caching you'll want to ensure that `config.action_controller.perform_caching` is set to `true`, if you're running in development mode. This flag is normally set in the corresponding `config/environments/*.rb` and caching is disabled by default for development and test, and enabled for production. +To start playing with caching you'll want to ensure that `config.action_controller.perform_caching` is set to `true` if you're running in development mode. This flag is normally set in the corresponding `config/environments/*.rb` and caching is disabled by default for development and test, and enabled for production. ```ruby config.action_controller.perform_caching = true @@ -144,7 +144,7 @@ It's called "Russian Doll Caching" because it nests multiple fragments. The adva ### Low-Level Caching -Sometimes you need to cache a particular value or query result, instead of caching view fragments. Rails caching mechanism works great for storing __any__ kind of information. +Sometimes you need to cache a particular value or query result instead of caching view fragments. Rails' caching mechanism works great for storing __any__ kind of information. The most efficient way to implement low-level caching is using the `Rails.cache.fetch` method. This method does both reading and writing to the cache. When passed only a single argument, the key is fetched and value from the cache is returned. If a block is passed, the result of the block will be cached to the given key and the result is returned. @@ -160,7 +160,7 @@ class Product < ActiveRecord::Base end ``` -NOTE: Notice that in this example we used `cache_key` method, so the resulting cache-key will be something like `products/233-20140225082222765838000/competing_price`. `cache_key` generates a string based on the model’s `id` and `updated_at` attributes. This is a common convention and has the benefit of invalidating the cache whenever the product is updated. In general, when you use low-level caching for instance level information, you need to generate a cache key. +NOTE: Notice that in this example we used the `cache_key` method, so the resulting cache-key will be something like `products/233-20140225082222765838000/competing_price`. `cache_key` generates a string based on the model’s `id` and `updated_at` attributes. This is a common convention and has the benefit of invalidating the cache whenever the product is updated. In general, when you use low-level caching for instance level information, you need to generate a cache key. ### SQL Caching @@ -219,7 +219,7 @@ There are some common options used by all cache implementations. These can be pa * `:compress` - This option can be used to indicate that compression should be used in the cache. This can be useful for transferring large cache entries over a slow network. -* `:compress_threshold` - This options is used in conjunction with the `:compress` option to indicate a threshold under which cache entries should not be compressed. This defaults to 16 kilobytes. +* `:compress_threshold` - This option is used in conjunction with the `:compress` option to indicate a threshold under which cache entries should not be compressed. This defaults to 16 kilobytes. * `:expires_in` - This option sets an expiration time in seconds for the cache entry when it will be automatically removed from the cache. @@ -227,7 +227,7 @@ There are some common options used by all cache implementations. These can be pa ### ActiveSupport::Cache::MemoryStore -This cache store keeps entries in memory in the same Ruby process. The cache store has a bounded size specified by the `:size` options to the initializer (default is 32Mb). When the cache exceeds the allotted size, a cleanup will occur and the least recently used entries will be removed. +This cache store keeps entries in memory in the same Ruby process. The cache store has a bounded size specified by the `:size` option to the initializer (default is 32Mb). When the cache exceeds the allotted size, a cleanup will occur and the least recently used entries will be removed. ```ruby config.cache_store = :memory_store, { size: 64.megabytes } @@ -243,7 +243,7 @@ This cache store uses the file system to store entries. The path to the director config.cache_store = :file_store, "/path/to/cache/directory" ``` -With this cache store, multiple server processes on the same host can share a cache. Servers processes running on different hosts could share a cache by using a shared file system, but that set up would not be ideal and is not recommended. The cache store is appropriate for low to medium traffic sites that are served off one or two hosts. +With this cache store, multiple server processes on the same host can share a cache. Server processes running on different hosts could share a cache by using a shared file system, but that set up would not be ideal and is not recommended. The cache store is appropriate for low to medium traffic sites that are served off one or two hosts. Note that the cache will grow until the disk is full unless you periodically clear out old entries. @@ -255,7 +255,7 @@ This cache store uses Danga's `memcached` server to provide a centralized cache When initializing the cache, you need to specify the addresses for all memcached servers in your cluster. If none is specified, it will assume memcached is running on the local host on the default port, but this is not an ideal set up for larger sites. -The `write` and `fetch` methods on this cache accept two additional options that take advantage of features specific to memcached. You can specify `:raw` to send a value directly to the server with no serialization. The value must be a string or number. You can use memcached direct operation like `increment` and `decrement` only on raw values. You can also specify `:unless_exist` if you don't want memcached to overwrite an existing entry. +The `write` and `fetch` methods on this cache accept two additional options that take advantage of features specific to memcached. You can specify `:raw` to send a value directly to the server with no serialization. The value must be a string or number. You can use memcached direct operations like `increment` and `decrement` only on raw values. You can also specify `:unless_exist` if you don't want memcached to overwrite an existing entry. ```ruby config.cache_store = :mem_cache_store, "cache-1.example.com", "cache-2.example.com" @@ -293,7 +293,7 @@ For more information about Ehcache for JRuby and Rails, see [http://ehcache.org/ ### ActiveSupport::Cache::NullStore -This cache store implementation is meant to be used only in development or test environments and it never stores anything. This can be very useful in development when you have code that interacts directly with `Rails.cache`, but caching may interfere with being able to see the results of code changes. With this cache store, all `fetch` and `read` operations will result in a miss. +This cache store implementation is meant to be used only in development or test environments and it never stores anything. This can be very useful in development when you have code that interacts directly with `Rails.cache` but caching may interfere with being able to see the results of code changes. With this cache store, all `fetch` and `read` operations will result in a miss. ```ruby config.cache_store = :null_store @@ -303,7 +303,7 @@ config.cache_store = :null_store You can create your own custom cache store by simply extending `ActiveSupport::Cache::Store` and implementing the appropriate methods. In this way, you can swap in any number of caching technologies into your Rails application. -To use a custom cache store, simple set the cache store to a new instance of the class. +To use a custom cache store, simply set the cache store to a new instance of the class. ```ruby config.cache_store = MyCacheStore.new @@ -311,7 +311,7 @@ config.cache_store = MyCacheStore.new ### Cache Keys -The keys used in a cache can be any object that responds to either `:cache_key` or to `:to_param`. You can implement the `:cache_key` method on your classes if you need to generate custom keys. Active Record will generate keys based on the class name and record id. +The keys used in a cache can be any object that responds to either `:cache_key` or `:to_param`. You can implement the `:cache_key` method on your classes if you need to generate custom keys. Active Record will generate keys based on the class name and record id. You can use Hashes and Arrays of values as cache keys. @@ -353,7 +353,7 @@ class ProductsController < ApplicationController end ``` -Instead of an options hash, you can also simply pass in a model, Rails will use the `updated_at` and `cache_key` methods for setting `last_modified` and `etag`: +Instead of an options hash, you can also simply pass in a model. Rails will use the `updated_at` and `cache_key` methods for setting `last_modified` and `etag`: ```ruby class ProductsController < ApplicationController diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md index c6863f68e6..ec3ac62b8c 100644 --- a/guides/source/debugging_rails_applications.md +++ b/guides/source/debugging_rails_applications.md @@ -17,7 +17,7 @@ After reading this guide, you will know: View Helpers for Debugging -------------------------- -One common task is to inspect the contents of a variable. In Rails, you can do this with three methods: +One common task is to inspect the contents of a variable. Rails provides three different ways to do this: * `debug` * `to_yaml` @@ -54,7 +54,7 @@ Title: Rails debugging guide ### `to_yaml` -Displaying an instance variable, or any other object or method, in YAML format can be achieved this way: +Alternatively, calling `to_yaml` on any object converts it to YAML. You can pass this converted object into the `simple_format` helper method to format the output. This is how `debug` does its magic. ```html+erb <%= simple_format @article.to_yaml %> @@ -64,9 +64,7 @@ Displaying an instance variable, or any other object or method, in YAML format c </p> ``` -The `to_yaml` method converts the method to YAML format leaving it more readable, and then the `simple_format` helper is used to render each line as in the console. This is how `debug` method does its magic. - -As a result of this, you will have something like this in your view: +The above code will render something like this: ```yaml --- !ruby/object Article @@ -94,7 +92,7 @@ Another useful method for displaying object values is `inspect`, especially when </p> ``` -Will be rendered as follows: +Will render: ``` [1, 2, 3, 4, 5] @@ -109,9 +107,9 @@ It can also be useful to save information to log files at runtime. Rails maintai ### What is the Logger? -Rails makes use of the `ActiveSupport::Logger` class to write log information. You can also substitute another logger such as `Log4r` if you wish. +Rails makes use of the `ActiveSupport::Logger` class to write log information. Other loggers, such as `Log4r`, may also be substituted. -You can specify an alternative logger in your `environment.rb` or any environment file: +You can specify an alternative logger in `environment.rb` or any other environment file, for example: ```ruby Rails.logger = Logger.new(STDOUT) @@ -130,7 +128,7 @@ TIP: By default, each log is created under `Rails.root/log/` and the log file is ### Log Levels When something is logged, it's printed into the corresponding log if the log -level of the message is equal or higher than the configured log level. If you +level of the message is equal to or higher than the configured log level. If you want to know the current log level, you can call the `Rails.logger.level` method. @@ -143,7 +141,7 @@ config.log_level = :warn # In any environment initializer, or Rails.logger.level = 0 # at any time ``` -This is useful when you want to log under development or staging, but you don't want to flood your production log with unnecessary information. +This is useful when you want to log under development or staging without flooding your production log with unnecessary information. TIP: The default Rails log level is `debug` in all environments. @@ -207,7 +205,7 @@ Adding extra logging like this makes it easy to search for unexpected or unusual When running multi-user, multi-account applications, it's often useful to be able to filter the logs using some custom rules. `TaggedLogging` -in Active Support helps in doing exactly that by stamping log lines with subdomains, request ids, and anything else to aid debugging such applications. +in Active Support helps you do exactly that by stamping log lines with subdomains, request ids, and anything else to aid debugging such applications. ```ruby logger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT)) @@ -217,34 +215,33 @@ logger.tagged("BCX") { logger.tagged("Jason") { logger.info "Stuff" } } # Logs " ``` ### Impact of Logs on Performance -Logging will always have a small impact on performance of your rails app, - particularly when logging to disk. However, there are a few subtleties: +Logging will always have a small impact on the performance of your Rails app, + particularly when logging to disk. Additionally, there are a few subtleties: Using the `:debug` level will have a greater performance penalty than `:fatal`, as a far greater number of strings are being evaluated and written to the log output (e.g. disk). -Another potential pitfall is that if you have many calls to `Logger` like this - in your code: +Another potential pitfall is too many calls to `Logger` in your code: ```ruby logger.debug "Person attributes hash: #{@person.attributes.inspect}" ``` -In the above example, There will be a performance impact even if the allowed +In the above example, there will be a performance impact even if the allowed output level doesn't include debug. The reason is that Ruby has to evaluate these strings, which includes instantiating the somewhat heavy `String` object -and interpolating the variables, and which takes time. +and interpolating the variables. Therefore, it's recommended to pass blocks to the logger methods, as these are -only evaluated if the output level is the same or included in the allowed level +only evaluated if the output level is the same as — or included in — the allowed level (i.e. lazy loading). The same code rewritten would be: ```ruby logger.debug {"Person attributes hash: #{@person.attributes.inspect}"} ``` -The contents of the block, and therefore the string interpolation, is only -evaluated if debug is enabled. This performance savings is only really +The contents of the block, and therefore the string interpolation, are only +evaluated if debug is enabled. This performance savings are only really noticeable with large amounts of logging, but it's a good practice to employ. Debugging with the `byebug` gem @@ -258,8 +255,7 @@ is your best companion. The debugger can also help you if you want to learn about the Rails source code but don't know where to start. Just debug any request to your application and -use this guide to learn how to move from the code you have written deeper into -Rails code. +use this guide to learn how to move from the code you have written into the underlying Rails code. ### Setup @@ -290,7 +286,7 @@ As soon as your application calls the `byebug` method, the debugger will be started in a debugger shell inside the terminal window where you launched your application server, and you will be placed at the debugger's prompt `(byebug)`. Before the prompt, the code around the line that is about to be run will be -displayed and the current line will be marked by '=>'. Like this: +displayed and the current line will be marked by '=>', like this: ``` [1, 10] in /PathTo/project/app/controllers/articles_controller.rb @@ -344,7 +340,7 @@ Processing by ArticlesController#index as HTML (byebug) ``` -Now it's time to explore and dig into your application. A good place to start is +Now it's time to explore your application. A good place to start is by asking the debugger for help. Type: `help` ``` @@ -365,9 +361,9 @@ continue edit frame kill pp reload skip undisplay TIP: To view the help menu for any command use `help <command-name>` at the debugger prompt. For example: _`help list`_. You can abbreviate any debugging command by supplying just enough letters to distinguish them from other -commands, so you can also use `l` for the `list` command, for example. +commands. For example, you can use `l` for the `list` command. -To see the previous ten lines you should type `list-` (or `l-`) +To see the previous ten lines you should type `list-` (or `l-`). ``` (byebug) l- @@ -386,7 +382,7 @@ To see the previous ten lines you should type `list-` (or `l-`) ``` -This way you can move inside the file, being able to see the code above and over +This way you can move inside the file and see the code above the line where you added the `byebug` call. Finally, to see where you are in the code again you can type `list=` @@ -416,8 +412,7 @@ contexts as you go through the different parts of the stack. The debugger creates a context when a stopping point or an event is reached. The context has information about the suspended program which enables the debugger to inspect the frame stack, evaluate variables from the perspective of the -debugged program, and contains information about the place where the debugged -program is stopped. +debugged program, and know the place where the debugged program is stopped. At any time you can call the `backtrace` command (or its alias `where`) to print the backtrace of the application. This can be very helpful to know how you got @@ -481,9 +476,8 @@ character and the number indicates the current thread of execution. * `thread resume _n_` resumes thread _n_. * `thread switch _n_` switches the current thread context to _n_. -This command is very helpful, among other occasions, when you are debugging -concurrent threads and need to verify that there are no race conditions in your -code. +This command is very helpful when you are debugging concurrent threads and need +to verify that there are no race conditions in your code. ### Inspecting Variables @@ -545,11 +539,11 @@ Now `@articles` is included in the instance variables, because the line defining was executed. TIP: You can also step into **irb** mode with the command `irb` (of course!). -This way an irb session will be started within the context you invoked it. But +This will start an irb session within the context you invoked it. But be warned: this is an experimental feature. The `var` method is the most convenient way to show variables and their values. -Let's let `byebug` help us with it. +Let's have `byebug` help us with it. ``` (byebug) help var @@ -561,7 +555,7 @@ v[ar] l[ocal] show local variables ``` This is a great way to inspect the values of the current context variables. For -example, to check that we have no local variables currently defined. +example, to check that we have no local variables currently defined: ``` (byebug) var local @@ -592,14 +586,14 @@ tracking the values of a variable while the execution goes on. 1: @articles = nil ``` -The variables inside the displaying list will be printed with their values after +The variables inside the displayed list will be printed with their values after you move in the stack. To stop displaying a variable use `undisplay _n_` where _n_ is the variable number (1 in the last example). ### Step by Step Now you should know where you are in the running trace and be able to print the -available variables. But lets continue and move on with the application +available variables. But let's continue and move on with the application execution. Use `step` (abbreviated `s`) to continue running your program until the next @@ -656,8 +650,8 @@ Next went up a frame because previous frame finished (byebug) ``` -If we use `step` in the same situation, we will literally go the next ruby -instruction to be executed. In this case, the activesupport's `week` method. +If we use `step` in the same situation, we will literally go to the next Ruby +instruction to be executed. In this case, Active Support's `week` method. ``` (byebug) step @@ -677,8 +671,7 @@ instruction to be executed. In this case, the activesupport's `week` method. (byebug) ``` -This is one of the best ways to find bugs in your code, or perhaps in Ruby on -Rails. +This is one of the best ways to find bugs in your code. ### Breakpoints @@ -814,7 +807,7 @@ controller. The console would be rendered next to your HTML content. ### Console -Inside any controller action or view, you can then invoke the console by +Inside any controller action or view, you can invoke the console by calling the `console` method. For example, in a controller: @@ -840,7 +833,7 @@ This will render a console inside your view. You don't need to care about the location of the `console` call; it won't be rendered on the spot of its invocation but next to your HTML content. -The console executes pure Ruby code. You can define and instantiate +The console executes pure Ruby code: You can define and instantiate custom classes, create new models and inspect variables. NOTE: Only one console can be rendered per request. Otherwise `web-console` @@ -865,7 +858,7 @@ to use it in production. Debugging Memory Leaks ---------------------- -A Ruby application (on Rails or not), can leak memory - either in the Ruby code +A Ruby application (on Rails or not), can leak memory — either in the Ruby code or at the C code level. In this section, you will learn how to find and fix such leaks by using tool @@ -896,7 +889,7 @@ footnotes that give request information and link back to your source via TextMate. * [Query Trace](https://github.com/ruckus/active-record-query-trace/tree/master) Adds query origin tracing to your logs. -* [Query Reviewer](https://github.com/nesquena/query_reviewer) This rails plugin +* [Query Reviewer](https://github.com/nesquena/query_reviewer) This Rails plugin not only runs "EXPLAIN" before each of your select queries in development, but provides a small DIV in the rendered output of each page with the summary of warnings for each query that it analyzed. @@ -908,7 +901,7 @@ standard Rails error page with a new one containing more contextual information, like source code and variable inspection. * [RailsPanel](https://github.com/dejan/rails_panel) Chrome extension for Rails development that will end your tailing of development.log. Have all information -about your Rails app requests in the browser - in the Developer Tools panel. +about your Rails app requests in the browser — in the Developer Tools panel. Provides insight to db/rendering/total times, parameter list, rendered views and more. diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md index 0aa2152d56..49834fa8a2 100644 --- a/guides/source/upgrading_ruby_on_rails.md +++ b/guides/source/upgrading_ruby_on_rails.md @@ -883,6 +883,20 @@ this gem such as `whitelist_attributes` or `mass_assignment_sanitizer` options. * To re-enable the old finders, you can use the [activerecord-deprecated_finders gem](https://github.com/rails/activerecord-deprecated_finders). +* Rails 4.0 has changed to default join table for `has_and_belongs_to_many` relations to strip the common prefix off the second table name. Any existing `has_and_belongs_to_many` relationship between models with a common prefix must be specified with the `join_table` option. For example: + +```ruby +CatalogCategory < ActiveRecord::Base + has_and_belongs_to_many :catalog_products, join_table: 'catalog_categories_catalog_products' +end + +CatalogProduct < ActiveRecord::Base + has_and_belongs_to_many :catalog_categories, join_table: 'catalog_categories_catalog_products' +end +``` + +* Note that the the prefix takes scopes into account as well, so relations between `Catalog::Category` and `Catalog::Product` or `Catalog::Category` and `CatalogProduct` need to be updated similarly. + ### Active Resource Rails 4.0 extracted Active Resource to its own gem. If you still need the feature you can add the [Active Resource gem](https://github.com/rails/activeresource) in your Gemfile. |