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diff --git a/guides/source/active_model_basics.md b/guides/source/active_model_basics.md index 3eaeeff389..fe2501bd87 100644 --- a/guides/source/active_model_basics.md +++ b/guides/source/active_model_basics.md @@ -1,20 +1,34 @@ +**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** + Active Model Basics =================== -This guide should provide you with all you need to get started using model classes. Active Model allows for Action Pack helpers to interact with non-Active Record models. Active Model also helps building custom ORMs for use outside of the Rails framework. +This guide should provide you with all you need to get started using model +classes. Active Model allows for Action Pack helpers to interact with +plain Ruby objects. Active Model also helps build custom ORMs for use +outside of the Rails framework. + +After reading this guide, you will know: -After reading this guide, you will know: +* How an Active Record model behaves. +* How Callbacks and validations work. +* How serializers work. +* The Rails internationalization (i18n) framework. -------------------------------------------------------------------------------- Introduction ------------ -Active Model is a library containing various modules used in developing frameworks that need to interact with the Rails Action Pack library. Active Model provides a known set of interfaces for usage in classes. Some of modules are explained below. +Active Model is a library containing various modules used in developing +classes that need some features present on Active Record. +Some of these modules are explained below. -### AttributeMethods +### Attribute Methods -The AttributeMethods module can add custom prefixes and suffixes on methods of a class. It is used by defining the prefixes and suffixes and which methods on the object will use them. +The `ActiveModel::AttributeMethods` module can add custom prefixes and suffixes +on methods of a class. It is used by defining the prefixes and suffixes and +which methods on the object will use them. ```ruby class Person @@ -38,14 +52,17 @@ end person = Person.new person.age = 110 -person.age_highest? # true -person.reset_age # 0 -person.age_highest? # false +person.age_highest? # => true +person.reset_age # => 0 +person.age_highest? # => false ``` ### Callbacks -Callbacks gives Active Record style callbacks. This provides an ability to define callbacks which run at appropriate times. After defining callbacks, you can wrap them with before, after and around custom methods. +`ActiveModel::Callbacks` gives Active Record style callbacks. This provides an +ability to define callbacks which run at appropriate times. +After defining callbacks, you can wrap them with before, after and around +custom methods. ```ruby class Person @@ -69,7 +86,9 @@ end ### Conversion -If a class defines `persisted?` and `id` methods, then you can include the `Conversion` module in that class and call the Rails conversion methods on objects of that class. +If a class defines `persisted?` and `id` methods, then you can include the +`ActiveModel::Conversion` module in that class and call the Rails conversion +methods on objects of that class. ```ruby class Person @@ -92,11 +111,13 @@ person.to_param # => nil ### Dirty -An object becomes dirty when it has gone through one or more changes to its attributes and has not been saved. This gives the ability to check whether an object has been changed or not. It also has attribute based accessor methods. Let's consider a Person class with attributes `first_name` and `last_name`: +An object becomes dirty when it has gone through one or more changes to its +attributes and has not been saved. `ActiveModel::Dirty` gives the ability to +check whether an object has been changed or not. It also has attribute based +accessor methods. Let's consider a Person class with attributes `first_name` +and `last_name`: ```ruby -require 'active_model' - class Person include ActiveModel::Dirty define_attribute_methods :first_name, :last_name @@ -135,7 +156,7 @@ person.changed? # => false person.first_name = "First Name" person.first_name # => "First Name" -# returns if any attribute has changed. +# returns true if any of the attributes have unsaved changes, false otherwise. person.changed? # => true # returns a list of attributes that have changed before saving. @@ -162,10 +183,11 @@ Track what was the previous value of the attribute. ```ruby # attr_name_was accessor -person.first_name_was # => "First Name" +person.first_name_was # => nil ``` -Track both previous and current value of the changed attribute. Returns an array if changed, else returns nil. +Track both previous and current value of the changed attribute. Returns an array +if changed, else returns nil. ```ruby # attr_name_change @@ -175,7 +197,8 @@ person.last_name_change # => nil ### Validations -Validations module adds the ability to class objects to validate them in Active Record style. +The `ActiveModel::Validations` module adds the ability to validate class objects +like in Active Record. ```ruby class Person @@ -188,7 +211,8 @@ class Person validates! :token, presence: true end -person = Person.new(token: "2b1f325") +person = Person.new +person.token = "2b1f325" person.valid? # => false person.name = 'vishnu' person.email = 'me' @@ -199,9 +223,9 @@ person.token = nil person.valid? # => raises ActiveModel::StrictValidationFailed ``` -### ActiveModel::Naming +### Naming -Naming adds a number of class methods which make the naming and routing +`ActiveModel::Naming` adds a number of class methods which make the naming and routing easier to manage. The module defines the `model_name` class method which will define a number of accessors using some `ActiveSupport::Inflector` methods. @@ -221,3 +245,255 @@ Person.model_name.i18n_key # => :person Person.model_name.route_key # => "people" Person.model_name.singular_route_key # => "person" ``` + +### Model + +`ActiveModel::Model` adds the ability to a class to work with Action Pack and +Action View right out of the box. + +```ruby +class EmailContact + include ActiveModel::Model + + attr_accessor :name, :email, :message + validates :name, :email, :message, presence: true + + def deliver + if valid? + # deliver email + end + end +end +``` + +When including `ActiveModel::Model` you get some features like: + +- model name introspection +- conversions +- translations +- validations + +It also gives you the ability to initialize an object with a hash of attributes, +much like any Active Record object. + +```ruby +email_contact = EmailContact.new(name: 'David', + email: 'david@example.com', + message: 'Hello World') +email_contact.name # => 'David' +email_contact.email # => 'david@example.com' +email_contact.valid? # => true +email_contact.persisted? # => false +``` + +Any class that includes `ActiveModel::Model` can be used with `form_for`, +`render` and any other Action View helper methods, just like Active Record +objects. + +### Serialization + +`ActiveModel::Serialization` provides basic serialization for your object. +You need to declare an attributes hash which contains the attributes you want to +serialize. Attributes must be strings, not symbols. + +```ruby +class Person + include ActiveModel::Serialization + + attr_accessor :name + + def attributes + {'name' => nil} + end +end +``` + +Now you can access a serialized hash of your object using the `serializable_hash`. + +```ruby +person = Person.new +person.serializable_hash # => {"name"=>nil} +person.name = "Bob" +person.serializable_hash # => {"name"=>"Bob"} +``` + +#### ActiveModel::Serializers + +Rails provides a `ActiveModel::Serializers::JSON` serializer. +This module automatically include the `ActiveModel::Serialization`. + +##### ActiveModel::Serializers::JSON + +To use the `ActiveModel::Serializers::JSON` you only need to change from +`ActiveModel::Serialization` to `ActiveModel::Serializers::JSON`. + +```ruby +class Person + include ActiveModel::Serializers::JSON + + attr_accessor :name + + def attributes + {'name' => nil} + end +end +``` + +With the `as_json` method you have a hash representing the model. + +```ruby +person = Person.new +person.as_json # => {"name"=>nil} +person.name = "Bob" +person.as_json # => {"name"=>"Bob"} +``` + +From a JSON string you define the attributes of the model. +You need to have the `attributes=` method defined on your class: + +```ruby +class Person + include ActiveModel::Serializers::JSON + + attr_accessor :name + + def attributes=(hash) + hash.each do |key, value| + send("#{key}=", value) + end + end + + def attributes + {'name' => nil} + end +end +``` + +Now it is possible to create an instance of person and set the attributes using `from_json`. + +```ruby +json = { name: 'Bob' }.to_json +person = Person.new +person.from_json(json) # => #<Person:0x00000100c773f0 @name="Bob"> +person.name # => "Bob" +``` + +### Translation + +`ActiveModel::Translation` provides integration between your object and the Rails +internationalization (i18n) framework. + +```ruby +class Person + extend ActiveModel::Translation +end +``` + +With the `human_attribute_name` you can transform attribute names into a more +human format. The human format is defined in your locale file. + +* config/locales/app.pt-BR.yml + + ```yml + pt-BR: + activemodel: + attributes: + person: + name: 'Nome' + ``` + +```ruby +Person.human_attribute_name('name') # => "Nome" +``` + +### Lint Tests + +`ActiveModel::Lint::Tests` allows you to test whether an object is compliant with +the Active Model API. + +* app/models/person.rb + + ```ruby + class Person + include ActiveModel::Model + + end + ``` + +* test/models/person_test.rb + + ```ruby + require 'test_helper' + + class PersonTest < ActiveSupport::TestCase + include ActiveModel::Lint::Tests + + def setup + @model = Person.new + end + end + ``` + +```bash +$ rake test + +Run options: --seed 14596 + +# Running: + +...... + +Finished in 0.024899s, 240.9735 runs/s, 1204.8677 assertions/s. + +6 runs, 30 assertions, 0 failures, 0 errors, 0 skips +``` + +An object is not required to implement all APIs in order to work with +Action Pack. This module only intends to provide guidance in case you want all +features out of the box. + +### SecurePassword + +`ActiveModel::SecurePassword` provides a way to securely store any +password in an encrypted form. On including this module, a +`has_secure_password` class method is provided which defines +an accessor named `password` with certain validations on it. + +#### Requirements + +`ActiveModel::SecurePassword` depends on [`bcrypt`](https://github.com/codahale/bcrypt-ruby 'BCrypt'), +so include this gem in your Gemfile to use `ActiveModel::SecurePassword` correctly. +In order to make this work, the model must have an accessor named `password_digest`. +The `has_secure_password` will add the following validations on the `password` accessor: + +1. Password should be present. +2. Password should be equal to its confirmation. +3. The maximum length of a password is 72 (required by `bcrypt` on which ActiveModel::SecurePassword depends) + +#### Examples + +```ruby +class Person + include ActiveModel::SecurePassword + has_secure_password + attr_accessor :password_digest +end + +person = Person.new + +# When password is blank. +person.valid? # => false + +# When the confirmation doesn't match the password. +person.password = 'aditya' +person.password_confirmation = 'nomatch' +person.valid? # => false + +# When the length of password exceeds 72. +person.password = person.password_confirmation = 'a' * 100 +person.valid? # => false + +# When all validations are passed. +person.password = person.password_confirmation = 'aditya' +person.valid? # => true +``` |