Class: ViewComponent::Base

Inherits:
ActionView::Base
  • Object
show all
Includes:
ActiveSupport::Configurable, Previewable
Defined in:
lib/view_component/base.rb

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Base

Returns a new instance of Base.



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# File 'lib/view_component/base.rb', line 88

def initialize(*); end

Class Attribute Details

.source_location ⇒ Object

Returns the value of attribute source_location.



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# File 'lib/view_component/base.rb', line 156

def source_location
  @source_location
end

Class Method Details

.call_method_name(variant) ⇒ Object 



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# File 'lib/view_component/base.rb', line 182

def call_method_name(variant)
  if variant.present? && variants.include?(variant)
    "call_#{variant}"
  else
    "call"
  end
end

.compile(raise_errors: false) ⇒ Object

Compile templates to instance methods, assuming they haven’t been compiled already.

Do as much work as possible in this step, as doing so reduces the amount of work done each time a component is rendered.



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# File 'lib/view_component/base.rb', line 200

def compile(raise_errors: false)
  return if compiled?

  if template_errors.present?
    raise ViewComponent::TemplateError.new(template_errors) if raise_errors
    return false
  end

  # Remove any existing singleton methods,
  # as Ruby warns when redefining a method.
  remove_possible_singleton_method(:variants)
  remove_possible_singleton_method(:collection_parameter)
  remove_possible_singleton_method(:collection_counter_parameter)
  remove_possible_singleton_method(:counter_argument_present?)

  define_singleton_method(:variants) do
    templates.map { |template| template[:variant] } + variants_from_inline_calls(inline_calls)
  end

  define_singleton_method(:collection_parameter) do
    if provided_collection_parameter
      provided_collection_parameter
    else
      name.demodulize.underscore.chomp("_component").to_sym
    end
  end

  define_singleton_method(:collection_counter_parameter) do
    "#{collection_parameter}_counter".to_sym
  end

  define_singleton_method(:counter_argument_present?) do
    instance_method(:initialize).parameters.map(&:second).include?(collection_counter_parameter)
  end

  validate_collection_parameter! if raise_errors

  # If template name annotations are turned on, a line is dynamically
  # added with a comment. In this case, we want to return a different
  # starting line number so errors that are raised will point to the
  # correct line in the component template.
  line_number =
    if ActionView::Base.respond_to?(:annotate_template_file_names) &&
      ActionView::Base.annotate_template_file_names
      -2
    else
      -1
    end

  templates.each do |template|
    # Remove existing compiled template methods,
    # as Ruby warns when redefining a method.
    method_name = call_method_name(template[:variant])
    undef_method(method_name.to_sym) if instance_methods.include?(method_name.to_sym)

    class_eval <<-RUBY, template[:path], line_number
      def #{method_name}
        @output_buffer = ActionView::OutputBuffer.new
        #{compiled_template(template[:path])}
      end
    RUBY
  end

  @compiled = true
end

.compiled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 190

def compiled?
  @compiled ||= false

  @compiled && ActionView::Base.cache_template_loading
end

.format ⇒ Object 



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# File 'lib/view_component/base.rb', line 271

def format
  :html
end

.identifier ⇒ Object 



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# File 'lib/view_component/base.rb', line 275

def identifier
  source_location
end

.inherited(child) ⇒ Object 



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# File 'lib/view_component/base.rb', line 168

def inherited(child)
  # If we're in Rails, add application url_helpers to the component context
  if defined?(Rails)
    child.include Rails.application.routes.url_helpers unless child < Rails.application.routes.url_helpers
  end

  # Derive the source location of the component Ruby file from the call stack.
  # We need to ignore `inherited` frames here as they indicate that `inherited`
  # has been re-defined by the consuming application, likely in ApplicationComponent.
  child.source_location = caller_locations(1, 10).reject { |l| l.label == "inherited" }[0].absolute_path

  super
end

.short_identifier ⇒ Object

Provide identifier for ActionView template annotations



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# File 'lib/view_component/base.rb', line 164

def short_identifier
  @short_identifier ||= defined?(Rails.root) ? source_location.sub("#{Rails.root}/", "") : source_location
end

.type ⇒ Object

we’ll eventually want to update this to support other types



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# File 'lib/view_component/base.rb', line 267

def type
  "text/html"
end

.validate_collection_parameter!(validate_default: false) ⇒ Object

Ensure the component initializer accepts the collection parameter. By default, we do not validate that the default parameter name is accepted, as support for collection rendering is optional.

Raises:

  • (ArgumentError) 


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# File 'lib/view_component/base.rb', line 297

def validate_collection_parameter!(validate_default: false)
  parameter = validate_default ? collection_parameter : provided_collection_parameter

  return unless parameter
  return if instance_method(:initialize).parameters.map(&:last).include?(parameter)

  raise ArgumentError.new(
    "#{self} initializer must accept " \
    "`#{parameter}` collection parameter."
  )
end

.with_collection(*args) ⇒ Object

Render a component collection.



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# File 'lib/view_component/base.rb', line 159

def with_collection(*args)
  Collection.new(self, *args)
end

.with_collection_parameter(param) ⇒ Object

Support overriding collection parameter name



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# File 'lib/view_component/base.rb', line 288

def with_collection_parameter(param)
  @provided_collection_parameter = param
end

.with_content_areas(*areas) ⇒ Object 



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# File 'lib/view_component/base.rb', line 279

def with_content_areas(*areas)
  if areas.include?(:content)
    raise ArgumentError.new ":content is a reserved content area name. Please use another name, such as ':body'"
  end
  attr_reader(*areas)
  self.content_areas = areas
end

Instance Method Details

#before_render_check ⇒ Object 



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# File 'lib/view_component/base.rb', line 80

def before_render_check
  # noop
end

#controller ⇒ Object 



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# File 'lib/view_component/base.rb', line 100

def controller
  @controller ||= view_context.controller
end

#format ⇒ Object

For caching, such as #cache_if



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# File 'lib/view_component/base.rb', line 120

def format
  @variant
end

#helpers ⇒ Object

Provides a proxy to access helper methods



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# File 'lib/view_component/base.rb', line 105

def helpers
  @helpers ||= view_context
end

#render(options = {}, args = {}, &block) ⇒ Object

If trying to render a partial or template inside a component, pass the render call to the parent view_context.



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# File 'lib/view_component/base.rb', line 92

def render(options = {}, args = {}, &block)
  if options.is_a?(String) || (options.is_a?(Hash) && options.has_key?(:partial))
    view_context.render(options, args, &block)
  else
    super
  end
end

#render? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 84

def render?
  true
end

#render_in(view_context, &block) ⇒ Object

Entrypoint for rendering components.

view_context: ActionView context from calling view block: optional block to be captured within the view context

returns HTML that has been escaped by the respective template handler

Example subclass:

app/components/my_component.rb: class MyComponent < ViewComponent::Base

def initialize(title:)
  @title = title
end

end

app/components/my_component.html.erb <span title=“<%= @title %>”>Hello, <%= content %>!</span>

In use: <%= render MyComponent.new(title: “greeting”) do %>world<% end %> returns: <span title=“greeting”>Hello, world!</span>



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# File 'lib/view_component/base.rb', line 43

def render_in(view_context, &block)
  self.class.compile(raise_errors: true)

  @view_context = view_context
  @lookup_context ||= view_context.lookup_context

  # required for path helpers in older Rails versions
  @view_renderer ||= view_context.view_renderer

  # For content_for
  @view_flow ||= view_context.view_flow

  # For i18n
  @virtual_path ||= virtual_path

  # For template variants (+phone, +desktop, etc.)
  @variant = @lookup_context.variants.first

  # For caching, such as #cache_if
  @current_template = nil unless defined?(@current_template)
  old_current_template = @current_template
  @current_template = self

  # Assign captured content passed to component as a block to @content
  @content = view_context.capture(self, &block) if block_given?

  before_render_check

  if render?
    send(self.class.call_method_name(@variant))
  else
    ""
  end
ensure
  @current_template = old_current_template
end

#view_cache_dependencies ⇒ Object

For caching, such as #cache_if



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# File 'lib/view_component/base.rb', line 115

def view_cache_dependencies
  []
end

#virtual_path ⇒ Object

Removes the first part of the path and the extension.



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# File 'lib/view_component/base.rb', line 110

def virtual_path
  self.class.source_location.gsub(%r{(.*app/components)|(\.rb)}, "")
end

#with(area, content = nil, &block) ⇒ Object

Assign the provided content to the content area accessor



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# File 'lib/view_component/base.rb', line 125

def with(area, content = nil, &block)
  unless content_areas.include?(area)
    raise ArgumentError.new "Unknown content_area '#{area}' - expected one of '#{content_areas}'"
  end

  if block_given?
    content = view_context.capture(&block)
  end

  instance_variable_set("@#{area}".to_sym, content)
  nil
end