Class: ViewComponent::Base

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

Constant Summary collapse

ViewContextCalledBeforeRenderError = 
Class.new(StandardError)
RESERVED_PARAMETER = 
:content

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 107

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 205

def source_location
  @source_location
end

.virtual_path ⇒ Object

Returns the value of attribute virtual_path.



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# File 'lib/view_component/base.rb', line 205

def virtual_path
  @virtual_path
end

Class Method Details

._after_compile ⇒ Object

EXPERIMENTAL: This API is experimental and may be removed at any time. Hook for allowing components to do work as part of the compilation process.

For example, one might compile component-specific assets at this point.



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# File 'lib/view_component/base.rb', line 30

def self._after_compile
  # noop
end

.collection_counter_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 335

def collection_counter_parameter
  "#{collection_parameter}_counter".to_sym
end

.collection_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 327

def collection_parameter
  if provided_collection_parameter
    provided_collection_parameter
  else
    name && name.demodulize.underscore.chomp("_component").to_sym
  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 247

def compile(raise_errors: false)
  template_compiler.compile(raise_errors: raise_errors)
end

.compiled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 239

def compiled?
  template_compiler.compiled?
end

.counter_argument_present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 339

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

.format ⇒ Object 



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# File 'lib/view_component/base.rb', line 260

def format
  :html
end

.identifier ⇒ Object 



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# File 'lib/view_component/base.rb', line 264

def identifier
  source_location
end

.inherited(child) ⇒ Object 



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# File 'lib/view_component/base.rb', line 217

def inherited(child)
  # Compile so child will inherit compiled `call_*` template methods that
  # `compile` defines
  compile

  # If Rails application is loaded, add application url_helpers to the component context
  # we need to check this to use this gem as a dependency
  if defined?(Rails) && Rails.application
    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

  # Removes the first part of the path and the extension.
  child.virtual_path = child.source_location.gsub(%r{(.*app/components)|(\.rb)}, "")

  super
end

.short_identifier ⇒ Object

Provide identifier for ActionView template annotations



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# File 'lib/view_component/base.rb', line 213

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

.template_compiler ⇒ Object 



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# File 'lib/view_component/base.rb', line 251

def template_compiler
  @_template_compiler ||= Compiler.new(self)
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 256

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 293

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

  return unless parameter
  return if initialize_parameter_names.include?(parameter)

  # If Ruby cannot parse the component class, then the initalize
  # parameters will be empty and ViewComponent will not be able to render
  # the component.
  if initialize_parameters.empty?
    raise ArgumentError.new(
      "#{self} initializer is empty or invalid."
    )
  end

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

.validate_initialization_parameters! ⇒ Object

Ensure the component initializer does not define invalid parameters that could override the framework’s methods.

Raises:

  • (ArgumentError) 


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# File 'lib/view_component/base.rb', line 317

def validate_initialization_parameters!
  return unless initialize_parameter_names.include?(RESERVED_PARAMETER)

  raise ArgumentError.new(
    "#{self} initializer cannot contain " \
    "`#{RESERVED_PARAMETER}` since it will override a " \
    "public ViewComponent method."
  )
end

.with_collection(collection, **args) ⇒ Object

Render a component collection.



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# File 'lib/view_component/base.rb', line 208

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

.with_collection_parameter(param) ⇒ Object

Support overriding collection parameter name



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# File 'lib/view_component/base.rb', line 284

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 268

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

  areas.each do |area|
    define_method area.to_sym do
      content unless content_evaluated? # ensure content is loaded so content_areas will be defined
      instance_variable_get(:"@#{area}") if instance_variable_defined?(:"@#{area}")
    end
  end

  self.content_areas = areas
end

Instance Method Details

#before_render ⇒ Object 



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# File 'lib/view_component/base.rb', line 95

def before_render
  before_render_check
end

#before_render_check ⇒ Object 



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# File 'lib/view_component/base.rb', line 99

def before_render_check
  # noop
end

#controller ⇒ Object

Raises:



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# File 'lib/view_component/base.rb', line 122

def controller
  raise ViewContextCalledBeforeRenderError, "`controller` can only be called at render time." if view_context.nil?
  @controller ||= view_context.controller
end

#format ⇒ Object

For caching, such as #cache_if



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# File 'lib/view_component/base.rb', line 144

def format
  # Ruby 2.6 throws a warning without checking `defined?`, 2.7 does not
  if defined?(@variant)
    @variant
  end
end

#helpers ⇒ Object

Provides a proxy to access helper methods from the context of the current controller

Raises:



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# File 'lib/view_component/base.rb', line 128

def helpers
  raise ViewContextCalledBeforeRenderError, "`helpers` can only be called at render time." if view_context.nil?
  @helpers ||= controller.view_context
end

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

Re-use original view_context if we’re not rendering a component.

This prevents an exception when rendering a partial inside of a component that has also been rendered outside of the component. This is due to the partials compiled template method existing in the parent ‘view_context`,

and not the component's `view_context`.



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# File 'lib/view_component/base.rb', line 114

def render(options = {}, args = {}, &block)
  if options.is_a? ViewComponent::Base
    super
  else
    view_context.render(options, args, &block)
  end
end

#render? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 103

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 58

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

  @_content_evaluated = false
  @_render_in_block = block

  before_render

  if render?
    render_template_for(@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 139

def view_cache_dependencies
  []
end

#virtual_path ⇒ Object

Exposes .virutal_path as an instance method



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# File 'lib/view_component/base.rb', line 134

def virtual_path
  self.class.virtual_path
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 152

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

#with_variant(variant) ⇒ Object 



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# File 'lib/view_component/base.rb', line 165

def with_variant(variant)
  @variant = variant

  self
end