Add API to register custom components

With this API, Simple Form will be possible to add custom components.
Methods defined in a component will be exposed to be used in the
wrapper as Simple::Components

Examples

  # The application needs to tell where the components will be.
  Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }

  # Create a custom component in the path specified above.
  # lib/components/input_group_component.rb
  module InpoutGroupComponent
    def preprend
      ...
    end

    def append
      ...
    end
  end

  SimpleForm.setup do |config|
    # Create a wrapper using the custom component.
    config.wrappers :input_group, tag: :div, error_class: :error do |b|
      b.use :label
      b.optional :prepend
      b.use :input
      b.use :append
    end
  end

  # Using the custom component in the form.
  <%= simple_form_for @blog, wrapper: input_group do |f| %>
    <%= f.input :title, prepend: true %>
  <% end %>

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Unreleased
 
-* Allow custom errors classes to inputs . [@feliperenan](https://github.com/feliperenan)
+* Add API to register custom components.[@feliperenan](https://github.com/feliperenan)
+* Allow custom errors classes to inputs.[@feliperenan](https://github.com/feliperenan)
 * Remove support from Rails 4.0, 4.1 and 4.2. [@feliperenan](https://github.com/feliperenan)
 * Add support for citext, hstore, json & jsonb column types. [@swrobel](https://github.com/swrobel)
 

README.md

@@ -989,6 +989,92 @@ when the content is present.
   end
 ```
 
+## Custom Components
+
+When you use custom wrappers, you might also be looking for a way to add custom components to your 
+wrapper. The default components are:
+
+```ruby
+:label         # The <label> tag alone
+:input         # The <input> tag alone
+:label_input   # The <label> and the <input> tags
+:hint          # The hint for the input
+:error         # The error for the input
+```
+
+A custom component might be interesting for you if your views look something like this:
+
+```erb
+<%= simple_form_for @blog do |f| %>
+  <div class="row">
+    <div class="span1 number">
+      1
+    </div>
+    <div class="span8">
+      <%= f.input :title %>
+    </div>
+  </div>
+  <div class="row">
+    <div class="span1 number">
+      2
+    </div>
+    <div class="span8">
+      <%= f.input :body, as: :text %>
+    </div>
+  </div>
+<% end %>
+```
+
+A cleaner method to create your views would be:
+
+```erb
+<%= simple_form_for @blog, wrapper: :with_numbers do |f| %>
+  <%= f.input :title, number: 1 %>
+  <%= f.input :body, as: :text, number: 2 %>
+<% end %>
+```
+
+To use the number option on the input, first, tells to Simple Form the place where the components
+will be:
+
+``` ruby
+# config/initializers/simple_form.rb
+Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }
+```
+
+Create a new component within the path specified above:
+
+```ruby
+# lib/components/numbers_component.rb
+module NumbersComponent
+  # To avoid deprecation warning, you need to make the wrapper_options explicit
+  # even when they won't be used.
+  def number(wrapper_options = nil)
+    @number ||= begin
+      options[:number].to_s.html_safe if options[:number].present?
+    end
+  end
+end
+
+SimpleForm.include_component(NumbersComponent)
+```
+
+Finally, add a new wrapper to the config/initializers/simple_form.rb file:
+
+```ruby
+config.wrappers :with_numbers, tag: 'div', class: 'row', error_class: 'error' do |b|
+  b.use :html5
+  b.use :number, wrap_with: { tag: 'div', class: 'span1 number'}
+  b.wrapper tag: 'div', :class: 'span8' do |ba|
+    ba.use :placeholder
+    ba.use :label
+    ba.use :input
+    ba.use :error, wrap_with: { tag: 'span', class: 'help-inline' }
+    ba.use :hint,  wrap_with: { tag: 'p', class: 'help-block' }
+  end
+end
+```
+
 ## HTML 5 Notice
 
 By default, **Simple Form** will generate input field types and attributes that are supported in HTML5,

lib/generators/simple_form/templates/config/initializers/simple_form.rb

@@ -1,4 +1,11 @@
 # frozen_string_literal: true
+#
+# Uncomment this and change the path if necessary to include your own
+# components.
+# See https://github.com/plataformatec/simple_form#custom-components to know
+# more about custom components.
+# Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }
+#
 # Use this setup block to configure all options available in SimpleForm.
 SimpleForm.setup do |config|
   # Wrappers are used by the form builder to generate a

lib/generators/simple_form/templates/config/initializers/simple_form_bootstrap.rb

@@ -1,4 +1,11 @@
 # frozen_string_literal: true
+#
+# Uncomment this and change the path if necessary to include your own
+# components.
+# See https://github.com/plataformatec/simple_form#custom-components to know
+# more about custom components.
+# Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }
+#
 # Use this setup block to configure all options available in SimpleForm.
 SimpleForm.setup do |config|
   config.error_notification_class = 'alert alert-danger'

lib/generators/simple_form/templates/config/initializers/simple_form_foundation.rb

@@ -1,4 +1,11 @@
 # frozen_string_literal: true
+#
+# Uncomment this and change the path if necessary to include your own
+# components.
+# See https://github.com/plataformatec/simple_form#custom-components to know
+# more about custom components.
+# Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }
+#
 # Use this setup block to configure all options available in SimpleForm.
 SimpleForm.setup do |config|
   # Don't forget to edit this file to adapt it to your needs (specially

lib/simple_form.rb

@@ -265,6 +265,49 @@ See https://github.com/plataformatec/simple_form/pull/997 for more information.
     @@configured = true
     yield self
   end
+
+  # Includes a component to be used by Simple Form. Methods defined in a
+  # component will be exposed to be used in the wrapper as Simple::Components
+  #
+  # Examples
+  #
+  #    # The application needs to tell where the components will be.
+  #    Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }
+  #
+  #    # Create a custom component in the path specified above.
+  #    # lib/components/input_group_component.rb
+  #    module InputGroupComponent
+  #      def prepend
+  #        ...
+  #      end
+  #
+  #      def append
+  #        ...
+  #      end
+  #    end
+  #
+  #    SimpleForm.setup do |config|
+  #      # Create a wrapper using the custom component.
+  #      config.wrappers :input_group, tag: :div, error_class: :error do |b|
+  #        b.use :label
+  #        b.optional :prepend
+  #        b.use :input
+  #        b.use :append
+  #      end
+  #    end
+  #
+  #    # Using the custom component in the form.
+  #    <%= simple_form_for @blog, wrapper: input_group do |f| %>
+  #      <%= f.input :title, prepend: true %>
+  #    <% end %>
+  #
+  def self.include_component(component)
+    if Module === component
+      SimpleForm::Inputs::Base.include(component)
+    else
+      raise TypeError, "SimpleForm.include_component expects a module but got: #{component.class}"
+    end
+  end
 end
 
 require 'simple_form/railtie' if defined?(Rails)

test/components/custom_components_test.rb

@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+# Module that represents a custom component.
+module Numbers
+  def number(wrapper_options = nil)
+    @number ||= options[:number].to_s.html_safe
+  end
+end
+
+# Module that represents a custom component.
+module InputGroup
+  def prepend(wrapper_options = nil)
+    span_tag = content_tag(:span, options[:prepend], class: 'input-group-text')
+    template.content_tag(:div, span_tag, class: 'input-group-prepend')
+  end
+
+  def append(wrapper_options = nil)
+    span_tag = content_tag(:span, options[:append], class: 'input-group-text')
+    template.content_tag(:div, span_tag, class: 'input-group-append')
+  end
+end
+
+class CustomComponentsTest < ActionView::TestCase
+  test 'includes the custom components' do
+    SimpleForm.include_component Numbers
+
+    custom_wrapper = SimpleForm.build tag: :div, class: "custom_wrapper" do |b|
+      b.use :number, wrap_with: { tag: 'div', class: 'number' }
+    end
+
+    with_form_for @user, :name, number: 1, wrapper: custom_wrapper
+
+    assert_select 'div.number', text: '1'
+  end
+
+  test 'includes custom components and use it as optional in the wrapper' do
+    SimpleForm.include_component InputGroup
+
+    custom_wrapper = SimpleForm.build tag: :div, class: 'custom_wrapper' do |b|
+      b.use :label
+      b.optional :prepend
+      b.use :input
+      b.use :append
+    end
+
+    with_form_for @user, :name, prepend: true, wrapper: custom_wrapper
+
+    assert_select 'div.input-group-prepend > span.input-group-text'
+    assert_select 'div.input-group-append > span.input-group-text'
+  end
+
+  test 'raises a TypeError when the component is not a Module' do
+    component = 'MyComponent'
+
+    exception = assert_raises TypeError do 
+      SimpleForm.include_component(component)
+    end
+    assert_equal exception.message, "SimpleForm.include_component expects a module but got: String"
+  end
+end