Class: ViewComponent::Base

Inherits:
ActionView::Base
  • Object
show all
Includes:
ActiveSupport::Configurable, ContentAreas, Previewable, SlotableV2, WithContentHelper
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

Methods included from WithContentHelper

#with_content

Methods included from SlotableV2

#get_slot, #set_slot

Methods included from ContentAreas

#with

Constructor Details

#initialize ⇒ Base

Returns a new instance of Base.



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# File 'lib/view_component/base.rb', line 141

def initialize(*); end

Class Attribute Details

.source_location ⇒ Object 



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# File 'lib/view_component/base.rb', line 298

def source_location
  @source_location
end

.virtual_path ⇒ Object 



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# File 'lib/view_component/base.rb', line 298

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 36

def self._after_compile
  # noop
end

._sidecar_files(extensions) ⇒ Object

EXPERIMENTAL: This API is experimental and may be removed at any time. Find sidecar files for the given extensions.

The provided array of extensions is expected to contain strings starting without the “dot”, example: ‘[“erb”, “haml”]`.

For example, one might collect sidecar CSS files that need to be compiled.



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# File 'lib/view_component/base.rb', line 308

def _sidecar_files(extensions)
  return [] unless source_location

  extensions = extensions.join(",")

  # view files in a directory named like the component
  directory = File.dirname(source_location)
  filename = File.basename(source_location, ".rb")
  component_name = name.demodulize.underscore

  # Add support for nested components defined in the same file.
  #
  # e.g.
  #
  # class MyComponent < ViewComponent::Base
  #   class MyOtherComponent < ViewComponent::Base
  #   end
  # end
  #
  # Without this, `MyOtherComponent` will not look for `my_component/my_other_component.html.erb`
  nested_component_files =
    if name.include?("::") && component_name != filename
      Dir["#{directory}/#{filename}/#{component_name}.*{#{extensions}}"]
    else
      []
    end

  # view files in the same directory as the component
  sidecar_files = Dir["#{directory}/#{component_name}.*{#{extensions}}"]

  sidecar_directory_files = Dir["#{directory}/#{component_name}/#{filename}.*{#{extensions}}"]

  (sidecar_files - [source_location] + sidecar_directory_files + nested_component_files).uniq
end

.collection_counter_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 484

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

.collection_iteration_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 494

def collection_iteration_parameter
  "#{collection_parameter}_iteration".to_sym
end

.collection_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 475

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 395

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

.compiled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 386

def compiled?
  compiler.compiled?
end

.compiler ⇒ Object 



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# File 'lib/view_component/base.rb', line 400

def compiler
  @__vc_compiler ||= Compiler.new(self)
end

.counter_argument_present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 489

def counter_argument_present?
  initialize_parameter_names.include?(collection_counter_parameter)
end

.format ⇒ Object 



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# File 'lib/view_component/base.rb', line 411

def format
  :html
end

.identifier ⇒ Object 



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# File 'lib/view_component/base.rb', line 416

def identifier
  source_location
end

.inherited(child) ⇒ Object 



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# File 'lib/view_component/base.rb', line 361

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{(.*#{Regexp.quote(ViewComponent::Base.view_component_path)})|(\.rb)}, ""
  )

  super
end

.iteration_argument_present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 499

def iteration_argument_present?
  initialize_parameter_names.include?(collection_iteration_parameter)
end

.short_identifier ⇒ Object

Provide identifier for ActionView template annotations



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# File 'lib/view_component/base.rb', line 356

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 406

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 435

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(
      "The #{self} initializer is empty or invalid." \
      "It must accept the parameter `#{parameter}` to render it as a collection.\n\n" \
      "To fix this issue, update the initializer to accept `#{parameter}`.\n\n" \
      "See https://viewcomponent.org/guide/collections.html for more information on rendering collections."
    )
  end

  raise ArgumentError.new(
    "The initializer for #{self} does not accept the parameter `#{parameter}`, " \
    "which is required in order to render it as a collection.\n\n" \
    "To fix this issue, update the initializer to accept `#{parameter}`.\n\n" \
    "See https://viewcomponent.org/guide/collections.html for more information on rendering collections."
  )
end

.validate_initialization_parameters! ⇒ Object

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

Raises:



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# File 'lib/view_component/base.rb', line 465

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

  raise ViewComponent::ComponentError.new(
    "#{self} initializer cannot accept the parameter `#{RESERVED_PARAMETER}`, as it will override a " \
    "public ViewComponent method. To fix this issue, rename the parameter."
  )
end

.with_collection(collection, **args) ⇒ Object

Render a component for each element in a collection ([documentation](/guide/collections)):

render(ProductsComponent.with_collection(@products, foo: :bar))

Parameters:

  • collection (Enumerable) —

    A list of items to pass the ViewComponent one at a time.

  • args (Arguments) —

    Arguments to pass to the ViewComponent every time.



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# File 'lib/view_component/base.rb', line 349

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

.with_collection_parameter(parameter) ⇒ Object

Set the parameter name used when rendering elements of a collection ([documentation](/guide/collections)):

with_collection_parameter :item

Parameters:

  • parameter (Symbol) —

    The parameter name used when rendering elements of a collection.



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# File 'lib/view_component/base.rb', line 425

def with_collection_parameter(parameter)
  @provided_collection_parameter = parameter
end

Instance Method Details

#_output_postamble ⇒ String

EXPERIMENTAL: Optional content to be returned after the rendered template.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 113

def _output_postamble
  ""
end

#before_render ⇒ void

This method returns an undefined value.

Called before rendering the component. Override to perform operations that depend on having access to the view context, such as helpers.



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# File 'lib/view_component/base.rb', line 121

def before_render
  before_render_check
end

#before_render_check ⇒ void

Deprecated.

Use ‘#before_render` instead. Will be removed in v3.0.0.

This method returns an undefined value.

Called after rendering the component.



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# File 'lib/view_component/base.rb', line 129

def before_render_check
  # noop
end

#controller ⇒ ActionController::Base

The current controller. Use sparingly as doing so introduces coupling that inhibits encapsulation & reuse, often making testing difficult.

Returns:

  • (ActionController::Base) 


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# File 'lib/view_component/base.rb', line 162

def controller
  if view_context.nil?
    raise(
      ViewContextCalledBeforeRenderError,
      "`#controller` cannot be used during initialization, as it depends " \
      "on the view context that only exists once a ViewComponent is passed to " \
      "the Rails render pipeline.\n\n" \
      "It's sometimes possible to fix this issue by moving code dependent on " \
      "`#controller` to a `#before_render` method: https://viewcomponent.org/api.html#before_render--void."
    )
  end

  @__vc_controller ||= view_context.controller
end

#format ⇒ Object

For caching, such as #cache_if



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# File 'lib/view_component/base.rb', line 212

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

#helpers ⇒ ActionView::Base

A proxy through which to access helpers. Use sparingly as doing so introduces coupling that inhibits encapsulation & reuse, often making testing difficult.

Returns:

  • (ActionView::Base) 


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# File 'lib/view_component/base.rb', line 181

def helpers
  if view_context.nil?
    raise(
      ViewContextCalledBeforeRenderError,
      "`#helpers` cannot be used during initialization, as it depends " \
      "on the view context that only exists once a ViewComponent is passed to " \
      "the Rails render pipeline.\n\n" \
      "It's sometimes possible to fix this issue by moving code dependent on " \
      "`#helpers` to a `#before_render` method: https://viewcomponent.org/api.html#before_render--void."
    )
  end

  @__vc_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 150

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

#render? ⇒ Boolean

Override to determine whether the ViewComponent should render.

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 136

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 65

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.)
  @__vc_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

  if block && defined?(@__vc_content_set_by_with_content)
    raise ArgumentError.new(
      "It looks like a block was provided after calling `with_content` on #{self.class.name}, " \
      "which means that ViewComponent doesn't know which content to use.\n\n" \
      "To fix this issue, use either `with_content` or a block."
    )
  end

  @__vc_content_evaluated = false
  @__vc_render_in_block = block

  before_render

  if render?
    render_template_for(@__vc_variant).to_s + _output_postamble
  else
    ""
  end
ensure
  @current_template = old_current_template
end

#request ⇒ ActionDispatch::Request

The current request. Use sparingly as doing so introduces coupling that inhibits encapsulation & reuse, often making testing difficult.

Returns:

  • (ActionDispatch::Request) 


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# File 'lib/view_component/base.rb', line 233

def request
  @request ||= controller.request if controller.respond_to?(:request)
end

#view_cache_dependencies ⇒ Object

For caching, such as #cache_if



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

def view_cache_dependencies
  []
end

#virtual_path ⇒ Object

Exposes .virtual_path as an instance method



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# File 'lib/view_component/base.rb', line 199

def virtual_path
  self.class.virtual_path
end

#with_variant(variant) ⇒ self

Use the provided variant instead of the one determined by the current request.

Parameters:

  • variant (Symbol) —

    The variant to be used by the component.

Returns:

  • (self) 


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# File 'lib/view_component/base.rb', line 223

def with_variant(variant)
  @__vc_variant = variant

  self
end