# frozen_string_literal: true
require "action_view"
require "active_support/configurable"
require "view_component/collection"
require "view_component/compile_cache"
require "view_component/content_areas"
require "view_component/polymorphic_slots"
require "view_component/previewable"
require "view_component/slotable"
require "view_component/slotable_v2"
require "view_component/translatable"
require "view_component/with_content_helper"
module ViewComponent
class Base < ActionView::Base
include ActiveSupport::Configurable
include ViewComponent::ContentAreas
include ViewComponent::PolymorphicSlots
include ViewComponent::Previewable
include ViewComponent::SlotableV2
include ViewComponent::Translatable
include ViewComponent::WithContentHelper
ViewContextCalledBeforeRenderError = Class.new(StandardError)
RESERVED_PARAMETER = :content
# For CSRF authenticity tokens in forms
delegate :form_authenticity_token, :protect_against_forgery?, :config, to: :helpers
class_attribute :content_areas
self.content_areas = [] # class_attribute:default doesn't work until Rails 5.2
# Config option that strips trailing whitespace in templates before compiling them.
class_attribute :__vc_strip_trailing_whitespace, instance_accessor: false, instance_predicate: false
self.__vc_strip_trailing_whitespace = false # class_attribute:default doesn't work until Rails 5.2
attr_accessor :__vc_original_view_context
# 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.
#
# @param view_context [ActionView::Base] The original view context.
# @return [void]
def set_original_view_context(view_context)
self.__vc_original_view_context = view_context
end
# 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.
# @private TODO: add documentation
def self._after_compile
# noop
end
# @!macro [attach] deprecated_generate_mattr_accessor
# @method generate_$1
# @deprecated Use `#generate.$1` instead. Will be removed in v3.0.0.
def self._deprecated_generate_mattr_accessor(name)
define_singleton_method("generate_#{name}".to_sym) do
generate.public_send(name)
end
define_singleton_method("generate_#{name}=".to_sym) do |value|
generate.public_send("#{name}=".to_sym, value)
end
end
_deprecated_generate_mattr_accessor :distinct_locale_files
_deprecated_generate_mattr_accessor :locale
_deprecated_generate_mattr_accessor :sidecar
_deprecated_generate_mattr_accessor :stimulus_controller
# 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.
#
# @return [String]
def render_in(view_context, &block)
self.class.compile(raise_errors: true)
@view_context = view_context
self.__vc_original_view_context ||= view_context
@output_buffer = ActionView::OutputBuffer.new
@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
# Subclass components that call `super` inside their template code will cause a
# double render if they emit the result:
#
# ```erb
# <%= super %> # double-renders
# <% super %> # does not double-render
# ```
#
# Calls `super`, returning `nil` to avoid rendering the result twice.
def render_parent
mtd = @__vc_variant ? "call_#{@__vc_variant}" : "call"
method(mtd).super_method.call
nil
end
# EXPERIMENTAL: Optional content to be returned after the rendered template.
#
# @return [String]
def _output_postamble
""
end
# Called before rendering the component. Override to perform operations that
# depend on having access to the view context, such as helpers.
#
# @return [void]
def before_render
before_render_check
end
# Called after rendering the component.
#
# @deprecated Use `#before_render` instead. Will be removed in v3.0.0.
# @return [void]
def before_render_check
# noop
end
# Override to determine whether the ViewComponent should render.
#
# @return [Boolean]
def render?
true
end
# @private
def initialize(*)
end
# 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`.
#
# @private
def render(options = {}, args = {}, &block)
if options.respond_to?(:set_original_view_context)
options.set_original_view_context(self.__vc_original_view_context)
super
else
__vc_original_view_context.render(options, args, &block)
end
end
# The current controller. Use sparingly as doing so introduces coupling
# that inhibits encapsulation & reuse, often making testing difficult.
#
# @return [ActionController::Base]
def controller
if view_context.nil?
raise(
ViewContextCalledBeforeRenderError,
"`#controller` can't 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
# A proxy through which to access helpers. Use sparingly as doing so introduces
# coupling that inhibits encapsulation & reuse, often making testing difficult.
#
# @return [ActionView::Base]
def helpers
if view_context.nil?
raise(
ViewContextCalledBeforeRenderError,
"`#helpers` can't 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
# 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
# Exposes .virtual_path as an instance method
#
# @private
def virtual_path
self.class.virtual_path
end
# For caching, such as #cache_if
# @private
def view_cache_dependencies
[]
end
# For caching, such as #cache_if
#
# @private
def format
# Ruby 2.6 throws a warning without checking `defined?`, 2.7 doesn't
if defined?(@__vc_variant)
@__vc_variant
end
end
# Use the provided variant instead of the one determined by the current request.
#
# @deprecated Will be removed in v3.0.0.
# @param variant [Symbol] The variant to be used by the component.
# @return [self]
def with_variant(variant)
@__vc_variant = variant
self
end
deprecate :with_variant, deprecator: ViewComponent::Deprecation
# The current request. Use sparingly as doing so introduces coupling that
# inhibits encapsulation & reuse, often making testing difficult.
#
# @return [ActionDispatch::Request]
def request
@request ||= controller.request if controller.respond_to?(:request)
end
private
attr_reader :view_context
def content
@__vc_content_evaluated = true
return @__vc_content if defined?(@__vc_content)
@__vc_content =
if @view_context && @__vc_render_in_block
view_context.capture(self, &@__vc_render_in_block)
elsif defined?(@__vc_content_set_by_with_content)
@__vc_content_set_by_with_content
end
end
def content_evaluated?
@__vc_content_evaluated
end
# Set the controller used for testing components:
#
# ```ruby
# config.view_component.test_controller = "MyTestController"
# ```
#
# Defaults to ApplicationController. Can also be configured on a per-test
# basis using `with_controller_class`.
#
mattr_accessor :test_controller
@@test_controller = "ApplicationController"
# Set if render monkey patches should be included or not in Rails <6.1:
#
# ```ruby
# config.view_component.render_monkey_patch_enabled = false
# ```
#
mattr_accessor :render_monkey_patch_enabled, instance_writer: false, default: true
# Path for component files
#
# ```ruby
# config.view_component.view_component_path = "app/my_components"
# ```
#
# Defaults to `app/components`.
#
mattr_accessor :view_component_path, instance_writer: false, default: "app/components"
# Parent class for generated components
#
# ```ruby
# config.view_component.component_parent_class = "MyBaseComponent"
# ```
#
# Defaults to nil. If this is falsy, generators will use
# "ApplicationComponent" if defined, "ViewComponent::Base" otherwise.
#
mattr_accessor :component_parent_class, instance_writer: false
# Configuration for generators.
#
# All options under this namespace default to `false` unless otherwise
# stated.
#
# #### #sidecar
#
# Always generate a component with a sidecar directory:
#
# ```ruby
# config.view_component.generate.sidecar = true
# ```
#
# #### #stimulus_controller
#
# Always generate a Stimulus controller alongside the component:
#
# ```ruby
# config.view_component.generate.stimulus_controller = true
# ```
#
# #### #locale
#
# Always generate translations file alongside the component:
#
# ```ruby
# config.view_component.generate.locale = true
# ```
#
# #### #distinct_locale_files
#
# Always generate as many translations files as available locales:
#
# ```ruby
# config.view_component.generate.distinct_locale_files = true
# ```
#
# One file will be generated for each configured `I18n.available_locales`,
# falling back to `[:en]` when no `available_locales` is defined.
#
# #### #preview
#
# Always generate preview alongside the component:
#
# ```ruby
# config.view_component.generate.preview = true
# ```
#
# Defaults to `false`.
mattr_accessor :generate, instance_writer: false, default: ActiveSupport::OrderedOptions.new(false)
class << self
# @private
attr_accessor :source_location, :virtual_path
# 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.
# @private TODO: add documentation
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.
#
# 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 - [source_location] + sidecar_directory_files + nested_component_files).uniq
end
# Render a component for each element in a collection ([documentation](/guide/collections)):
#
# ```ruby
# render(ProductsComponent.with_collection(@products, foo: :bar))
# ```
#
# @param collection [Enumerable] A list of items to pass the ViewComponent one at a time.
# @param args [Arguments] Arguments to pass to the ViewComponent every time.
def with_collection(collection, **args)
Collection.new(self, collection, **args)
end
# Provide identifier for ActionView template annotations
#
# @private
def short_identifier
@short_identifier ||= defined?(Rails.root) ? source_location.sub("#{Rails.root}/", "") : source_location
end
# @private
def inherited(child)
# Compile so child will inherit compiled `call_*` template methods that
# `compile` defines
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.instance_methods(false).include?(:render_template_for) && !child.compiled?
child.class_eval <<~RUBY, __FILE__, __LINE__ + 1
def render_template_for(variant = nil)
# Force compilation here so the compiler always redefines render_template_for.
# This is mostly a safeguard to prevent infinite recursion.
self.class.compile(raise_errors: true, force: true)
# .compile replaces this method; call the new one
render_template_for(variant)
end
RUBY
end
# 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].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)}, ""
)
# Set collection parameter to the extended component
child.with_collection_parameter provided_collection_parameter
super
end
# @private
def compiled?
compiler.compiled?
end
# 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.
# @private
def compile(raise_errors: false, force: false)
compiler.compile(raise_errors: raise_errors, force: force)
end
# @private
def compiler
@__vc_compiler ||= Compiler.new(self)
end
# we'll eventually want to update this to support other types
# @private
def type
"text/html"
end
# @private
def format
:html
end
# @private
def identifier
source_location
end
# Set the parameter name used when rendering elements of a collection ([documentation](/guide/collections)):
#
# ```ruby
# with_collection_parameter :item
# ```
#
# @param parameter [Symbol] The parameter name used when rendering elements of a collection.
def with_collection_parameter(parameter)
@provided_collection_parameter = parameter
end
# Strips trailing whitespace from templates before compiling them.
#
# ```ruby
# class MyComponent < ViewComponent::Base
# strip_trailing_whitespace
# end
# ```
#
# @param value [Boolean] Whether or not to strip newlines.
def strip_trailing_whitespace(value = true)
self.__vc_strip_trailing_whitespace = value
end
# Whether trailing whitespace will be stripped before compilation.
#
# @return [Boolean]
def strip_trailing_whitespace?
__vc_strip_trailing_whitespace
end
# 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.
# @private TODO: add documentation
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 can't 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} doesn't 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
# Ensure the component initializer doesn't define
# invalid parameters that could override the framework's
# methods.
# @private TODO: add documentation
def validate_initialization_parameters!
return unless initialize_parameter_names.include?(RESERVED_PARAMETER)
raise ViewComponent::ComponentError.new(
"#{self} initializer can't accept the parameter `#{RESERVED_PARAMETER}`, as it will override a " \
"public ViewComponent method. To fix this issue, rename the parameter."
)
end
# @private
def collection_parameter
provided_collection_parameter || name && name.demodulize.underscore.chomp("_component").to_sym
end
# @private
def collection_counter_parameter
"#{collection_parameter}_counter".to_sym
end
# @private
def counter_argument_present?
initialize_parameter_names.include?(collection_counter_parameter)
end
# @private
def collection_iteration_parameter
"#{collection_parameter}_iteration".to_sym
end
# @private
def iteration_argument_present?
initialize_parameter_names.include?(collection_iteration_parameter)
end
private
def initialize_parameter_names
return attribute_names.map(&:to_sym) if respond_to?(:attribute_names)
return attribute_types.keys.map(&:to_sym) if Rails::VERSION::MAJOR <= 5 && respond_to?(:attribute_types)
initialize_parameters.map(&:last)
end
def initialize_parameters
instance_method(:initialize).parameters
end
def provided_collection_parameter
@provided_collection_parameter ||= nil
end
end
ActiveSupport.run_load_hooks(:view_component, self)
end
end