Class: ViewComponent::Base

Inherits:
Object
  • Object
show all
Includes:
ActionView::Helpers, ActiveSupport::CoreExt::ERBUtil, ERB::Escape, InlineTemplate, Slotable, Translatable, WithContentHelper
Defined in:
lib/view_component/base.rb

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from WithContentHelper

#with_content

Methods included from Translatable

#__vc_i18n_scope, #translate

Methods included from Slotable

#__vc_get_slot, #__vc_set_polymorphic_slot, #__vc_set_slot

Constructor Details

#initialize ⇒ Base

Including Rails.application.routes.url_helpers defines an initializer that accepts (...), so we have to define our own empty initializer to overwrite it.



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

def initialize
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_name, *args) ⇒ Object 



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# File 'lib/view_component/base.rb', line 342

def method_missing(method_name, *args) # rubocop:disable Style/MissingRespondToMissing
  super
rescue => e # rubocop:disable Style/RescueStandardError
  e.set_backtrace e.backtrace.tap(&:shift)
  raise e, <<~MESSAGE.chomp if view_context && e.is_a?(NameError) && helpers.respond_to?(method_name)
    #{e.message}

    You may be trying to call a method provided as a view helper. Did you mean `helpers.#{method_name}`?
  MESSAGE

  raise
end

Class Attribute Details

.identifier ⇒ String

The file path of the component Ruby file.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 573

def identifier
  @identifier
end

.virtual_path ⇒ Object 



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# File 'lib/view_component/base.rb', line 579

def virtual_path
  @virtual_path
end

Instance Attribute Details

#__vc_original_view_context ⇒ Object

Returns the value of attribute __vc_original_view_context.



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# File 'lib/view_component/base.rb', line 74

def __vc_original_view_context
  @__vc_original_view_context
end

#current_template ⇒ Object (readonly)

Returns the value of attribute current_template.



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# File 'lib/view_component/base.rb', line 75

def current_template
  @current_template
end

Class Method Details

.__vc_collection_counter_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 773

def __vc_collection_counter_parameter
  @__vc_collection_counter_parameter ||= :"#{__vc_collection_parameter}_counter"
end

.__vc_collection_iteration_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 783

def __vc_collection_iteration_parameter
  @__vc_collection_iteration_parameter ||= :"#{__vc_collection_parameter}_iteration"
end

.__vc_collection_parameter ⇒ Object 



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# File 'lib/view_component/base.rb', line 768

def __vc_collection_parameter
  @__vc_provided_collection_parameter ||= name && name.demodulize.underscore.chomp("_component").to_sym
end

.__vc_compile(raise_errors: false, force: false) ⇒ Object 



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# File 'lib/view_component/base.rb', line 638

def __vc_compile(raise_errors: false, force: false)
  __vc_compiler.compile(raise_errors: raise_errors, force: force)
end

.__vc_compiled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 686

def __vc_compiled?
  __vc_compiler.compiled?
end

.__vc_compiler ⇒ Object 



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# File 'lib/view_component/base.rb', line 706

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

.__vc_counter_argument_present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 778

def __vc_counter_argument_present?
  __vc_initialize_parameter_names.include?(__vc_collection_counter_parameter)
end

.__vc_ensure_compiled ⇒ Object 



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# File 'lib/view_component/base.rb', line 701

def __vc_ensure_compiled
  __vc_compile unless __vc_compiled?
end

.__vc_iteration_argument_present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 788

def __vc_iteration_argument_present?
  __vc_initialize_parameter_names.include?(__vc_collection_iteration_parameter)
end

.__vc_validate_collection_parameter!(validate_default: false) ⇒ Object

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

Raises:



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# File 'lib/view_component/base.rb', line 748

def __vc_validate_collection_parameter!(validate_default: false)
  parameter = validate_default ? __vc_collection_parameter : __vc_provided_collection_parameter

  return unless parameter
  return if __vc_initialize_parameter_names.include?(parameter) || __vc_splatted_keyword_argument_present?

  raise MissingCollectionArgumentError.new(name, parameter)
end

.__vc_validate_initialization_parameters! ⇒ Object

Ensure the component initializer doesn't define invalid parameters that could override the framework's methods.

Raises:



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# File 'lib/view_component/base.rb', line 761

def __vc_validate_initialization_parameters!
  return unless __vc_initialize_parameter_names.include?(:content)

  raise ReservedParameterError.new(name, :content)
end

.after_compile ⇒ Object

Hook called by the compiler after a component is compiled.

Extensions can override this class method to run logic after compilation (e.g., generate helpers, register metadata, etc.).

By default, this is a no-op.



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# File 'lib/view_component/base.rb', line 696

def after_compile
  # no-op by default
end

.config ⇒ ActiveSupport::OrderedOptions

Returns the current config.

Returns:

  • (ActiveSupport::OrderedOptions) 


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# File 'lib/view_component/base.rb', line 39

def config
  module_parents.each do |module_parent|
    next unless module_parent.respond_to?(:config)
    module_parent_config = module_parent.config.try(:view_component)
    return module_parent_config if module_parent_config
  end
  ViewComponent::Config.current
end

.inherited(child) ⇒ Object 



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# File 'lib/view_component/base.rb', line 643

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

  # Give the child its own personal #render_template_for to protect against the case when
  # eager loading is disabled and the parent component is rendered before the child. In
  # such a scenario, the parent will override ViewComponent::Base#render_template_for,
  # meaning it will not be called for any children and thus not compile their templates.
  if !child.method_defined?(:render_template_for, false) && !child.__vc_compiled?
    child.class_eval <<~RUBY, __FILE__, __LINE__ + 1
      def render_template_for(requested_details)
        # Force compilation here so the compiler always redefines render_template_for.
        # This is mostly a safeguard to prevent infinite recursion.
        self.class.__vc_compile(raise_errors: true, force: true)
        # .__vc_compile replaces this method; call the new one
        render_template_for(requested_details)
      end
    RUBY
  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.
  # We use `base_label` method here instead of `label` to avoid cases where the method
  # owner is included in a prefix like `ApplicationComponent.inherited`.
  child.identifier = caller_locations(1, 10).reject { |l| l.base_label == "inherited" }[0].path
  child.virtual_path = child.name&.underscore

  # Set collection parameter to the extended component
  child.with_collection_parameter(__vc_provided_collection_parameter)

  if method_defined?(:render_template_for, false)
    vc_ancestor_calls = defined?(@__vc_ancestor_calls) ? @__vc_ancestor_calls.dup : []

    vc_ancestor_calls.unshift(instance_method(:render_template_for))
    child.instance_variable_set(:@__vc_ancestor_calls, vc_ancestor_calls)
  end

  super
end

.sidecar_files(extensions) ⇒ Object

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.

Parameters:

  • extensions (Array<String>) —

    Extensions of which to return matching sidecar files.



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# File 'lib/view_component/base.rb', line 588

def sidecar_files(extensions)
  return [] unless identifier
  return [] unless name

  extensions = extensions.join(",")

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

  # Add support for nested components defined in the same file.
  #
  # for example
  #
  # 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 - [identifier] + sidecar_directory_files + nested_component_files).uniq
end

.strip_trailing_whitespace(value = true) ⇒ Object

Strips trailing whitespace from templates before compiling them.

class MyComponent < ViewComponent::Base
  strip_trailing_whitespace
end

Parameters:

  • value (Boolean) (defaults to: true) —

    Whether to strip newlines.



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# File 'lib/view_component/base.rb', line 731

def strip_trailing_whitespace(value = true)
  self.__vc_strip_trailing_whitespace = value
end

.strip_trailing_whitespace? ⇒ Boolean

Whether trailing whitespace will be stripped before compilation.

Returns:

  • (Boolean) 


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# File 'lib/view_component/base.rb', line 738

def strip_trailing_whitespace?
  __vc_strip_trailing_whitespace
end

.with_collection(collection, spacer_component: nil, **args) ⇒ Object

Render a component for each element in a collection (documentation):

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

Parameters:

  • collection (Enumerable) —

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

  • spacer_component (ViewComponent::Base) (defaults to: nil) —

    Component instance to be rendered between items.

  • args (Arguments) —

    Arguments to pass to the ViewComponent every time.



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# File 'lib/view_component/base.rb', line 633

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

.with_collection_parameter(parameter) ⇒ Object

Set the parameter name used when rendering elements of a collection (documentation):

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 717

def with_collection_parameter(parameter)
  @__vc_provided_collection_parameter = parameter
  @__vc_initialize_parameters = nil
end

Instance Method Details

#__vc_request ⇒ Object 



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

def __vc_request
  # The current request (if present, as mailers/jobs/etc do not have a request)
  @__vc_request ||= controller.request if controller.respond_to?(:request)
end

#around_render ⇒ void

This method returns an undefined value.

Called around rendering the component. Override to wrap the rendering of a component in custom instrumentation, etc.



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# File 'lib/view_component/base.rb', line 252

def around_render
  yield
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 244

def before_render
  # noop
end

#capture ⇒ Object

Sync @output_buffer with the view context's current output buffer before capturing. Form helpers create builders with @template_object pointing to the component. When those builders later call capture inside a partial (whose _run allocated a fresh OutputBuffer on the view context), the component's stale @output_buffer would capture from the wrong buffer. Temporarily switching to the view context's buffer keeps both in sync.



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# File 'lib/view_component/base.rb', line 305

def capture(...)
  old_output_buffer = @output_buffer
  @output_buffer = view_context.output_buffer if view_context
  super
ensure
  @output_buffer = old_output_buffer
end

#content ⇒ String

The content passed to the component instance as a block.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 394

def content
  @__vc_content_evaluated = true
  return @__vc_content if defined?(@__vc_content)

  @__vc_content =
    if __vc_render_in_block_provided?
      with_captured_virtual_path(@old_virtual_path) do
        view_context.capture(self, &@__vc_render_in_block)
      end
    elsif __vc_content_set_by_with_content_defined?
      @__vc_content_set_by_with_content
    end
end

#content? ⇒ Boolean

Whether content has been passed to the component.

Returns:

  • (Boolean) 


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

def content?
  __vc_render_in_block_provided? || __vc_content_set_by_with_content_defined?
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)

Raises:



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

def controller
  raise ControllerCalledBeforeRenderError if view_context.nil?

  @__vc_controller ||= view_context.controller
end

#format ⇒ Object

Rails expects us to define format on all renderables, but we do not know the format of a ViewComponent until runtime.



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# File 'lib/view_component/base.rb', line 372

def format
  nil
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)

Raises:



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

def helpers
  raise HelpersCalledBeforeRenderError if view_context.nil?

  # Attempt to re-use the original view_context passed to the first
  # component rendered in the rendering pipeline. This prevents the
  # instantiation of a new view_context via `controller.view_context` which
  # always returns a new instance of the view context class.
  #
  # This allows ivars to remain persisted when using the same helper via
  # `helpers` across multiple components and partials.
  @__vc_helpers ||= __vc_original_view_context || controller.view_context
end

#output_postamble ⇒ String

Optional content to be returned after the rendered template.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 236

def output_postamble
  @@default_output_postamble ||= "".html_safe
end

#output_preamble ⇒ String

Optional content to be returned before the rendered template.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 229

def output_preamble
  @@default_output_preamble ||= "".html_safe
end

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

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

As of v4, ViewComponent::Base re-uses the existing view context created by ActionView, meaning the current view context and the original view context are the same object. set_original_view_context is still called to maintain backwards compatibility.



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

def render(options = {}, args = {}, &block)
  if options.respond_to?(:set_original_view_context)
    options.set_original_view_context(__vc_original_view_context)

    # We assume options is a component, so there's no need to evaluate the
    # block in the view context as we do below.
    @view_context.render(options, args, &block)
  elsif block
    __vc_original_view_context.render(options, args) do
      # capture the block output in the view context of the component
      output = capture(&block)

      # Partials are rendered to their own buffer and do not append to the
      # original @output_buffer we retain a reference to in #render_in. This
      # is a problem since the block passed to us here in the #render method
      # is evaluated within the context of ViewComponent::Base, and thus
      # appends to the original @output_buffer. To avoid this, we evaluate the
      # block in the view context instead, which will append to the output buffer
      # created for the partial.
      __vc_original_view_context.capture { output }
    end
  else
    __vc_original_view_context.render(options, args)
  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 259

def render?
  true
end

#render_in(view_context, &block) ⇒ String

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.

Returns:

  • (String) 


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# File 'lib/view_component/base.rb', line 106

def render_in(view_context, **, &block)
  self.class.__vc_compile(raise_errors: true) unless self.class.__vc_compiled?

  __vc_check_reused_instance!
  __vc_reset_render_state!

  @view_context = view_context
  @old_virtual_path = view_context.instance_variable_get(:@virtual_path)
  self.__vc_original_view_context = view_context

  @output_buffer = view_context.output_buffer

  @lookup_context = view_context.lookup_context

  # For content_for
  @view_flow = view_context.view_flow

  # For i18n
  @virtual_path ||= virtual_path

  # Describes the inferred request constraints (locales, formats, variants)
  @__vc_requested_details = @lookup_context.vc_requested_details

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

  if block && defined?(@__vc_content_set_by_with_content)
    raise DuplicateContentError.new(self.class.name)
  end

  @__vc_content_evaluated = false
  remove_instance_variable(:@__vc_content) if defined?(@__vc_content)
  @__vc_render_in_block = block
  @view_context.instance_variable_set(:@virtual_path, virtual_path)

  before_render

  if render?
    value = nil

    @output_buffer.with_buffer do
      inner_rendered_template = nil
      around_rendered_template = around_render do
        inner_rendered_template = render_template_for(@__vc_requested_details).to_s
      end

      # If `around_render` returned the same object the block yielded, the inner
      # template's escaping is authoritative and we can trust the result. If the
      # user replaced/wrapped the value, re-check HTML safety to prevent
      # bypassing the escaping applied to normal `#call` return values
      # (GHSA-97jw-64cj-jc58).
      rendered_template = if around_rendered_template.equal?(inner_rendered_template)
        around_rendered_template
      else
        __vc_safe_around_render_output(around_rendered_template)
      end

      # Avoid allocating new string when output_preamble and output_postamble are blank
      value = if output_preamble.blank? && output_postamble.blank?
        rendered_template
      else
        __vc_safe_output_preamble + rendered_template + __vc_safe_output_postamble
      end
    end

    if ActionView::Base.annotate_rendered_view_with_filenames && current_template.inline_call? && request&.format == :html
      identifier = defined?(Rails.root) ? self.class.identifier.sub("#{Rails.root}/", "") : self.class.identifier
      value = "<!-- BEGIN #{identifier} -->".html_safe + value + "<!-- END #{identifier} -->".html_safe
    end

    value
  else
    "".html_safe
  end
ensure
  view_context.instance_variable_set(:@virtual_path, @old_virtual_path)
  @current_template = old_current_template
  @__vc_rendered = true
end

#render_parent ⇒ Object

Subclass components that call super inside their template code will cause a double render if they emit the result.

<%= super %> # double-renders
<% super %> # doesn't double-render

super also doesn't consider the current variant. render_parent renders the parent template considering the current variant and emits the result without double-rendering.



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# File 'lib/view_component/base.rb', line 198

def render_parent
  render_parent_to_string
  nil
end

#render_parent_to_string ⇒ Object

Renders the parent component to a string and returns it. This method is meant to be used inside custom #call methods when a string result is desired, eg.

def call
  "<div>#{render_parent_to_string}</div>"
end

When rendering the parent inside an .erb template, use #render_parent instead.



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

def render_parent_to_string
  @__vc_parent_render_level ||= 0 # ensure a good starting value

  begin
    target_render = self.class.instance_variable_get(:@__vc_ancestor_calls)[@__vc_parent_render_level]
    @__vc_parent_render_level += 1

    target_render.bind_call(self, @__vc_requested_details)
  ensure
    @__vc_parent_render_level -= 1
  end
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 381

def request
  __vc_request
end

#set_original_view_context(view_context) ⇒ void

This method returns an undefined value.

Components render in their own view context. Helpers and other functionality require a reference to the original Rails view context, an instance of ActionView::Base. Use this method to set a reference to the original view context. Objects that implement this method will render in the component's view context, while objects that don't will render in the original view context so helpers, etc work as expected.

Parameters:

  • view_context (ActionView::Base) —

    The original view context.



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# File 'lib/view_component/base.rb', line 87

def set_original_view_context(view_context)
  # noop
end

#view_cache_dependencies ⇒ Object

For caching, such as #cache_if



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# File 'lib/view_component/base.rb', line 365

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 359

def virtual_path
  self.class.virtual_path
end

#with_captured_virtual_path(captured_path) ⇒ Object

Temporarily sets the virtual path to the captured value, then restores it. This ensures translations and other path-dependent code execute with the correct scope.



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# File 'lib/view_component/base.rb', line 418

def with_captured_virtual_path(captured_path)
  old_virtual_path = @view_context.instance_variable_get(:@virtual_path)
  @view_context.instance_variable_set(:@virtual_path, captured_path)
  yield
ensure
  @view_context.instance_variable_set(:@virtual_path, old_virtual_path)
end