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joelhawksley merged 1 commit into from
Jan 16, 2025
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Refactor compiler to use ActionView's partial sorting algorithm #2158

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11 changes: 11 additions & 0 deletions docs/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,17 @@

*Stephen Nelson*

* BREAKING: Use ActionView's `lookup_context` for picking templates instead of the request format.

3.15 added support for using templates that match the request format, i.e. if `/resource.csv` is requested then

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[Microsoft.Foreign] Use 'that is' instead of 'i.e.'.

Raw Output:
{"message": "[Microsoft.Foreign] Use 'that is' instead of 'i.e.'.", "location": {"path": "docs/CHANGELOG.md", "range": {"start": {"line": 33, "column": 73}}}, "severity": "ERROR"}
ViewComponents would pick `_component.csv.erb` over `_component.html.erb`.

With this release, the request format is no longer considered and instead ViewComponent will use the Rails logic
for picking the most appropriate template type, i.e. the csv template will be used if it matches the `Accept` header

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[vale] reported by reviewdog 🐶
[Microsoft.Foreign] Use 'that is' instead of 'i.e.'.

Raw Output:
{"message": "[Microsoft.Foreign] Use 'that is' instead of 'i.e.'.", "location": {"path": "docs/CHANGELOG.md", "range": {"start": {"line": 37, "column": 51}}}, "severity": "ERROR"}
or because the controller uses a `respond_to` block to pick the response format.

*Stephen Nelson*

Comment on lines +31 to +41
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@joelhawksley joelhawksley Jan 16, 2025

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Suggested change
* BREAKING: Use ActionView's `lookup_context` for picking templates instead of the request format.
3.15 added support for using templates that match the request format, i.e. if `/resource.csv` is requested then
ViewComponents would pick `_component.csv.erb` over `_component.html.erb`.
With this release, the request format is no longer considered and instead ViewComponent will use the Rails logic
for picking the most appropriate template type, i.e. the csv template will be used if it matches the `Accept` header
or because the controller uses a `respond_to` block to pick the response format.
*Stephen Nelson*
* BREAKING: Use ActionView's `lookup_context` for picking templates instead of the request format.
`3.15` added support for using templates that match the request format: when`/resource.csv` is requested then ViewComponent would pick `_component.csv.erb` over `_component.html.erb`.
With this release, the request format is no longer considered and instead ViewComponent will use the Rails logic for picking the most appropriate template type. For example, the `csv` template will be used if it matches the `Accept` header or because the controller uses a `respond_to` block to pick the response format.
*Stephen Nelson*

* Ensure HTML output safety wrapper is used for all inline templates.

*Joel Hawksley*
Expand Down
25 changes: 13 additions & 12 deletions lib/view_component/base.rb
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Expand Up @@ -9,6 +9,7 @@
require "view_component/errors"
require "view_component/inline_template"
require "view_component/preview"
require "view_component/request_details"
require "view_component/slotable"
require "view_component/slotable_default"
require "view_component/template"
Expand Down Expand Up @@ -63,6 +64,8 @@ def set_original_view_context(view_context)
self.__vc_original_view_context = view_context
end

using RequestDetails

# Entrypoint for rendering components.
#
# - `view_context`: ActionView context from calling view
Expand Down Expand Up @@ -90,13 +93,12 @@ def render_in(view_context, &block)
# For i18n
@virtual_path ||= virtual_path

# For template variants (+phone, +desktop, etc.)
@__vc_variant ||= @lookup_context.variants.first
# 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
@current_template = self

if block && defined?(@__vc_content_set_by_with_content)
raise DuplicateContentError.new(self.class.name)
Expand All @@ -108,7 +110,7 @@ def render_in(view_context, &block)
before_render

if render?
rendered_template = render_template_for(@__vc_variant, __vc_request&.format&.to_sym).to_s
rendered_template = render_template_for(@__vc_requested_details).to_s

# Avoid allocating new string when output_preamble and output_postamble are blank
if output_preamble.blank? && output_postamble.blank?
Expand Down Expand Up @@ -156,7 +158,7 @@ def render_parent_to_string
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_variant)
target_render.bind_call(self, @__vc_requested_details)
ensure
@__vc_parent_render_level -= 1
end
Expand Down Expand Up @@ -267,11 +269,10 @@ def view_cache_dependencies
[]
end

# For caching, such as #cache_if
#
# @private
# Rails expects us to define `format` on all renderables,
# but we do not know the `format` of a ViewComponent until runtime.
def format
@__vc_variant if defined?(@__vc_variant)
nil
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@sfnelson sfnelson Nov 8, 2024

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I've spent some time investigating why this code returned the variant and I still don't really understand why. It was added during 1.x and it's been refactored numerous times. I don't think this has any meaningful contribution to caching anymore as Rails cache already uses the LookupContext@details ivar as an entry point to caching. Any cache generated from a ViewComponent render would already be keyed by the specific LookupContext details including locale, variants, formats, and handlers.

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If that's the case, then let's just remove this method entirely. It's optional anyways: https://github.com/rails/rails/blob/main/actionview/lib/action_view/template/renderable.rb#L26

end

# The current request. Use sparingly as doing so introduces coupling that
Expand Down Expand Up @@ -328,7 +329,7 @@ def content_evaluated?
end

def maybe_escape_html(text)
return text if __vc_request && !__vc_request.format.html?
return text if @current_template && !@current_template.html?
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@sfnelson sfnelson Nov 8, 2024

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Note that current_template is set by render_template_for now, so this logic takes into account the format picked by the renderer (e.g. if the chosen template is json then the before/after strings won't be HTML sanitised).

return text if text.blank?

if text.html_safe?
Expand Down Expand Up @@ -517,12 +518,12 @@ def inherited(child)
# 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, format = nil)
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.compile(raise_errors: true, force: true)
# .compile replaces this method; call the new one
render_template_for(variant, format)
render_template_for(requested_details)
end
RUBY
end
Expand Down
86 changes: 42 additions & 44 deletions lib/view_component/compiler.rb
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Expand Up @@ -55,6 +55,23 @@ def compile(raise_errors: false, force: false)
end
end

# @return all matching compiled templates, in priority order based on the requested details from LookupContext
#
# @param [ActionView::TemplateDetails::Requested] requested_details i.e. locales, formats, variants
def find_templates_for(requested_details)
filtered_templates = @templates.select do |template|
template.details.matches?(requested_details)
end

if filtered_templates.count > 1
filtered_templates.sort_by! do |template|
template.details.sort_key_for(requested_details)
end
end

filtered_templates
end

private

attr_reader :templates
Expand All @@ -64,40 +81,25 @@ def define_render_template_for
template.compile_to_component
end

method_body =
if @templates.one?
@templates.first.safe_method_name_call
elsif (template = @templates.find(&:inline?))
template.safe_method_name_call
else
branches = []

@templates.each do |template|
conditional =
if template.inline_call?
"variant&.to_sym == #{template.variant.inspect}"
else
[
template.default_format? ? "(format == #{ViewComponent::Base::VC_INTERNAL_DEFAULT_FORMAT.inspect} || format.nil?)" : "format == #{template.format.inspect}",
template.variant.nil? ? "variant.nil?" : "variant&.to_sym == #{template.variant.inspect}"
].join(" && ")
end

branches << [conditional, template.safe_method_name_call]
end
@component.silence_redefinition_of_method(:render_template_for)

out = branches.each_with_object(+"") do |(conditional, branch_body), memo|
memo << "#{(!memo.present?) ? "if" : "elsif"} #{conditional}\n #{branch_body}\n"
if @templates.one?
template = @templates.first
safe_call = template.safe_method_name_call
@component.define_method(:render_template_for) do |_|
@current_template = template
instance_exec(&safe_call)
end
else
compiler = self
@component.define_method(:render_template_for) do |details|
if (@current_template = compiler.find_templates_for(details).first)
instance_exec(&@current_template.safe_method_name_call)
else
raise MissingTemplateError.new(self.class.name, details)
end
out << "else\n #{templates.find { _1.variant.nil? && _1.default_format? }.safe_method_name_call}\nend"
end

@component.silence_redefinition_of_method(:render_template_for)
@component.class_eval <<-RUBY, __FILE__, __LINE__ + 1
def render_template_for(variant = nil, format = nil)
#{method_body}
end
RUBY
end

def template_errors
Expand Down Expand Up @@ -168,15 +170,18 @@ def template_errors

def gather_templates
@templates ||=
begin
if @component.inline_template.present?
[Template::Inline.new(
component: @component,
inline_template: @component.inline_template
)]
else
path_parser = ActionView::Resolver::PathParser.new
templates = @component.sidecar_files(
ActionView::Template.template_handler_extensions
).map do |path|
details = path_parser.parse(path).details
out = Template::File.new(component: @component, path: path, details: details)

out
Template::File.new(component: @component, path: path, details: details)
end

component_instance_methods_on_self = @component.instance_methods(false)
Expand All @@ -186,17 +191,10 @@ def gather_templates
).flat_map { |ancestor| ancestor.instance_methods(false).grep(/^call(_|$)/) }
.uniq
.each do |method_name|
templates << Template::InlineCall.new(
component: @component,
method_name: method_name,
defined_on_self: component_instance_methods_on_self.include?(method_name)
)
end

if @component.inline_template.present?
templates << Template::Inline.new(
templates << Template::InlineCall.new(
component: @component,
inline_template: @component.inline_template
method_name: method_name,
defined_on_self: component_instance_methods_on_self.include?(method_name)
)
end

Expand Down
16 changes: 16 additions & 0 deletions lib/view_component/errors.rb
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Expand Up @@ -38,6 +38,22 @@ def initialize(example)
end
end

class MissingTemplateError < StandardError
MESSAGE =
"No templates for COMPONENT match the request DETAIL.\n\n" \
"To fix this issue, provide a suitable template."

def initialize(component, request_detail)
detail = {
locale: request_detail.locale,
formats: request_detail.formats,
variants: request_detail.variants,
handlers: request_detail.handlers
}
super(MESSAGE.gsub("COMPONENT", component).gsub("DETAIL", detail.inspect))
end
end

class DuplicateContentError < StandardError
MESSAGE =
"It looks like a block was provided after calling `with_content` on COMPONENT, " \
Expand Down
30 changes: 30 additions & 0 deletions lib/view_component/request_details.rb
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@@ -0,0 +1,30 @@
# frozen_string_literal: true

module ViewComponent
# LookupContext computes and encapsulates @details for each request
# so that it doesn't need to be recomputed on each partial render.
# This data is wrapped in ActionView::TemplateDetails::Requested and
# used by instances of ActionView::Resolver to choose which template
# best matches the request.
#
# ActionView considers this logic internal to template/partial resolution.
# We're exposing it to the compiler via `refine` so that ViewComponent
# can match Rails' template picking logic.
module RequestDetails
refine ActionView::LookupContext do
# Return an abstraction for matching and sorting available templates
# based on the current lookup context details.
#
# @return ActionView::TemplateDetails::Requested
# @see ActionView::LookupContext#detail_args_for
# @see ActionView::FileSystemResolver#_find_all
def vc_requested_details(user_details = {})
# The hash `user_details` would normally be the standard arguments that
# `render` accepts, but there's currently no mechanism for users to
# provide these when calling render on a ViewComponent.
details, cached = detail_args_for(user_details)
cached || ActionView::TemplateDetails::Requested.new(**details)
end
end
end
end
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