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Diffstat (limited to 'guides/source/active_support_core_extensions.md')
| -rw-r--r-- | guides/source/active_support_core_extensions.md | 101 |
1 files changed, 64 insertions, 37 deletions
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index 047999d4cf..0aca6db9b6 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -172,7 +172,7 @@ NOTE: Defined in `active_support/core_ext/object/duplicable.rb`. ### `deep_dup` -The `deep_dup` method returns deep copy of a given object. Normally, when you `dup` an object that contains other objects, Ruby does not `dup` them, so it creates a shallow copy of the object. If you have an array with a string, for example, it will look like this: +The `deep_dup` method returns a deep copy of a given object. Normally, when you `dup` an object that contains other objects, Ruby does not `dup` them, so it creates a shallow copy of the object. If you have an array with a string, for example, it will look like this: ```ruby array = ['string'] @@ -248,6 +248,13 @@ end @person.try { |p| "#{p.first_name} #{p.last_name}" } ``` +Note that `try` will swallow no-method errors, returning nil instead. If you want to protect against typos, use `try!` instead: + +```ruby +@number.try(:nest) # => nil +@number.try!(:nest) # NoMethodError: undefined method `nest' for 1:Fixnum +``` + NOTE: Defined in `active_support/core_ext/object/try.rb`. ### `class_eval(*args, &block)` @@ -390,7 +397,7 @@ The method `with_options` provides a way to factor out common options in a serie Given a default options hash, `with_options` yields a proxy object to a block. Within the block, methods called on the proxy are forwarded to the receiver with their options merged. For example, you get rid of the duplication in: ```ruby -class Account < ActiveRecord::Base +class Account < ApplicationRecord has_many :customers, dependent: :destroy has_many :products, dependent: :destroy has_many :invoices, dependent: :destroy @@ -401,7 +408,7 @@ end this way: ```ruby -class Account < ActiveRecord::Base +class Account < ApplicationRecord with_options dependent: :destroy do |assoc| assoc.has_many :customers assoc.has_many :products @@ -453,7 +460,7 @@ NOTE: Defined in `active_support/core_ext/object/instance_variables.rb`. #### `instance_variable_names` -The method `instance_variable_names` returns an array. Each name includes the "@" sign. +The method `instance_variable_names` returns an array. Each name includes the "@" sign. ```ruby class C @@ -510,17 +517,17 @@ Extensions to `Module` Using plain Ruby you can wrap methods with other methods, that's called _alias chaining_. -For example, let's say you'd like params to be strings in functional tests, as they are in real requests, but still want the convenience of assigning integers and other kind of values. To accomplish that you could wrap `ActionController::TestCase#process` this way in `test/test_helper.rb`: +For example, let's say you'd like params to be strings in functional tests, as they are in real requests, but still want the convenience of assigning integers and other kind of values. To accomplish that you could wrap `ActionDispatch::IntegrationTest#process` this way in `test/test_helper.rb`: ```ruby -ActionController::TestCase.class_eval do +ActionDispatch::IntegrationTest.class_eval do # save a reference to the original process method alias_method :original_process, :process # now redefine process and delegate to original_process - def process(action, params=nil, session=nil, flash=nil, http_method='GET') + def process('GET', path, params: nil, headers: nil, env: nil, xhr: false) params = Hash[*params.map {|k, v| [k, v.to_s]}.flatten] - original_process(action, params, session, flash, http_method) + original_process('GET', path, params: params) end end ``` @@ -530,10 +537,10 @@ That's the method `get`, `post`, etc., delegate the work to. That technique has a risk, it could be the case that `:original_process` was taken. To try to avoid collisions people choose some label that characterizes what the chaining is about: ```ruby -ActionController::TestCase.class_eval do +ActionDispatch::IntegrationTest.class_eval do def process_with_stringified_params(...) params = Hash[*params.map {|k, v| [k, v.to_s]}.flatten] - process_without_stringified_params(action, params, session, flash, http_method) + process_without_stringified_params(method, path, params: params) end alias_method :process_without_stringified_params, :process alias_method :process, :process_with_stringified_params @@ -543,10 +550,10 @@ end The method `alias_method_chain` provides a shortcut for that pattern: ```ruby -ActionController::TestCase.class_eval do +ActionDispatch::IntegrationTest.class_eval do def process_with_stringified_params(...) params = Hash[*params.map {|k, v| [k, v.to_s]}.flatten] - process_without_stringified_params(action, params, session, flash, http_method) + process_without_stringified_params(method, path, params: params) end alias_method_chain :process, :stringified_params end @@ -561,7 +568,7 @@ NOTE: Defined in `active_support/core_ext/module/aliasing.rb`. Model attributes have a reader, a writer, and a predicate. You can alias a model attribute having the corresponding three methods defined for you in one shot. As in other aliasing methods, the new name is the first argument, and the old name is the second (one mnemonic is that they go in the same order as if you did an assignment): ```ruby -class User < ActiveRecord::Base +class User < ApplicationRecord # You can refer to the email column as "login". # This can be meaningful for authentication code. alias_attribute :login, :email @@ -869,7 +876,7 @@ The macro `delegate` offers an easy way to forward methods. Let's imagine that users in some application have login information in the `User` model but name and other data in a separate `Profile` model: ```ruby -class User < ActiveRecord::Base +class User < ApplicationRecord has_one :profile end ``` @@ -877,7 +884,7 @@ end With that configuration you get a user's name via their profile, `user.profile.name`, but it could be handy to still be able to access such attribute directly: ```ruby -class User < ActiveRecord::Base +class User < ApplicationRecord has_one :profile def name @@ -889,7 +896,7 @@ end That is what `delegate` does for you: ```ruby -class User < ActiveRecord::Base +class User < ApplicationRecord has_one :profile delegate :name, to: :profile @@ -1703,6 +1710,20 @@ The method `parameterize` normalizes its receiver in a way that can be used in p "Kurt Gödel".parameterize # => "kurt-godel" ``` +To preserve the case of the string, set the `preserve_case` argument to true. By default, `preserve_case` is set to false. + +```ruby +"John Smith".parameterize(preserve_case: true) # => "John-Smith" +"Kurt Gödel".parameterize(preserve_case: true) # => "Kurt-Godel" +``` + +To use a custom separator, override the `separator` argument. + +```ruby +"John Smith".parameterize(separator: "_") # => "john\_smith" +"Kurt Gödel".parameterize(separator: "_") # => "kurt\_godel" +``` + In fact, the result string is wrapped in an instance of `ActiveSupport::Multibyte::Chars`. NOTE: Defined in `active_support/core_ext/string/inflections.rb`. @@ -1865,15 +1886,15 @@ The methods `to_date`, `to_time`, and `to_datetime` are basically convenience wr ```ruby "2010-07-27".to_date # => Tue, 27 Jul 2010 -"2010-07-27 23:37:00".to_time # => Tue Jul 27 23:37:00 UTC 2010 +"2010-07-27 23:37:00".to_time # => 2010-07-27 23:37:00 +0200 "2010-07-27 23:37:00".to_datetime # => Tue, 27 Jul 2010 23:37:00 +0000 ``` `to_time` receives an optional argument `:utc` or `:local`, to indicate which time zone you want the time in: ```ruby -"2010-07-27 23:42:00".to_time(:utc) # => Tue Jul 27 23:42:00 UTC 2010 -"2010-07-27 23:42:00".to_time(:local) # => Tue Jul 27 23:42:00 +0200 2010 +"2010-07-27 23:42:00".to_time(:utc) # => 2010-07-27 23:42:00 UTC +"2010-07-27 23:42:00".to_time(:local) # => 2010-07-27 23:42:00 +0200 ``` Default is `:utc`. @@ -1936,6 +1957,8 @@ as well as adding or subtracting their results from a Time object. For example: (4.months + 5.years).from_now ``` +NOTE: Defined in `active_support/core_ext/numeric/time.rb` + ### Formatting Enables the formatting of numbers in a variety of ways. @@ -2001,12 +2024,14 @@ Produce a string representation of a number rounded to a precision: Produce a string representation of a number as a human-readable number of bytes: ```ruby -123.to_s(:human_size) # => 123 Bytes -1234.to_s(:human_size) # => 1.21 KB -12345.to_s(:human_size) # => 12.1 KB -1234567.to_s(:human_size) # => 1.18 MB -1234567890.to_s(:human_size) # => 1.15 GB -1234567890123.to_s(:human_size) # => 1.12 TB +123.to_s(:human_size) # => 123 Bytes +1234.to_s(:human_size) # => 1.21 KB +12345.to_s(:human_size) # => 12.1 KB +1234567.to_s(:human_size) # => 1.18 MB +1234567890.to_s(:human_size) # => 1.15 GB +1234567890123.to_s(:human_size) # => 1.12 TB +1234567890123456.to_s(:human_size) # => 1.1 PB +1234567890123456789.to_s(:human_size) # => 1.07 EB ``` Produce a string representation of a number in human-readable words: @@ -2071,30 +2096,22 @@ Extensions to `BigDecimal` -------------------------- ### `to_s` -The method `to_s` is aliased to `to_formatted_s`. This provides a convenient way to display a BigDecimal value in floating-point notation: +The method `to_s` provides a default specifier of "F". This means that a simple call to `to_s` will result in floating point representation instead of engineering notation: ```ruby BigDecimal.new(5.00, 6).to_s # => "5.0" ``` -### `to_formatted_s` - -Te method `to_formatted_s` provides a default specifier of "F". This means that a simple call to `to_formatted_s` or `to_s` will result in floating point representation instead of engineering notation: - -```ruby -BigDecimal.new(5.00, 6).to_formatted_s # => "5.0" -``` - and that symbol specifiers are also supported: ```ruby -BigDecimal.new(5.00, 6).to_formatted_s(:db) # => "5.0" +BigDecimal.new(5.00, 6).to_s(:db) # => "5.0" ``` Engineering notation is still supported: ```ruby -BigDecimal.new(5.00, 6).to_formatted_s("e") # => "0.5E1" +BigDecimal.new(5.00, 6).to_s("e") # => "0.5E1" ``` Extensions to `Enumerable` @@ -2193,6 +2210,16 @@ removed: NOTE: Defined in `active_support/core_ext/enumerable.rb`. +### `pluck` + +The method `pluck` returns an array based on the given key: + +```ruby +[{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name) # => ["David", "Rafael", "Aaron"] +``` + +NOTE: Defined in `active_support/core_ext/enumerable.rb`. + Extensions to `Array` --------------------- @@ -2883,7 +2910,7 @@ The method `transform_values` accepts a block and returns a hash that has applie ``` There's also the bang variant `transform_values!` that applies the block operations to values in the very receiver. -NOTE: Defined in `active_support/core_text/hash/transform_values.rb`. +NOTE: Defined in `active_support/core_ext/hash/transform_values.rb`. ### Slicing |