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Introduce class_names helper 

As a follow-up to https://github.com/rails/rails/pull/37872,
this change introduces a class_names view helper
to make it easier to conditionally apply class names
in views.

Before:
<div class="<%= item.for_sale? ? 'active' : '' %>">

After:
<div class="<%= class_names(active: item.for_sale?) %>">

We've been using this helper in the GitHub monolith
since 2016.

Co-authored-by: Aaron Patterson <tenderlove@github.com>
This commit is contained in:
Joel Hawksley 2019-12-09 16:16:09 -07:00
parent 32b363b246
commit f24734a7e1
No known key found for this signature in database
GPG Key ID: 38C0E0D4558502CD
2 changed files with 45 additions and 20 deletions
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54
actionview/lib/action_view/helpers/tag_helper.rb
View File

@ -94,7 +94,7 @@ module ActionView
def tag_option(key, value, escape)
case value
when Array, Hash
value = build_tag_values(value) if key.to_s == "class"
value = TagHelper.build_tag_values(value) if key.to_s == "class"
value = escape ? safe_join(value, " ") : value.join(" ")
else
value = escape ? ERB::Util.unwrapped_html_escape(value) : value.to_s
@ -104,25 +104,6 @@ module ActionView
end
private
def build_tag_values(*args)
tag_values = []
args.each do |tag_value|
case tag_value
when Hash
tag_value.each do |key, val|
tag_values << key if val
end
when Array
tag_values << build_tag_values(*tag_value).presence
else
tag_values << tag_value.to_s if tag_value.present?
end
end
tag_values.compact.flatten
end
def prefix_tag_option(prefix, key, value, escape)
key = "#{prefix}-#{key.to_s.dasherize}"
unless value.is_a?(String) || value.is_a?(Symbol) || value.is_a?(BigDecimal)
@ -309,6 +290,19 @@ module ActionView
end
end
# Returns a string of class names built from +args+.
#
# ==== Examples
# class_names("foo", "bar")
# # => "foo bar"
# class_names({ foo: true, bar: false })
# # => "foo"
# class_names(nil, false, 123, "", "foo", { bar: true })
# # => "foo bar"
def class_names(*args)
safe_join(build_tag_values(*args), " ")
end
# Returns a CDATA section with the given +content+. CDATA sections
# are used to escape blocks of text containing characters which would
# otherwise be recognized as markup. CDATA sections begin with the string
@ -339,6 +333,26 @@ module ActionView
end
private
def build_tag_values(*args)
tag_values = []
args.each do |tag_value|
case tag_value
when Hash
tag_value.each do |key, val|
tag_values << key if val
end
when Array
tag_values << build_tag_values(*tag_value).presence
else
tag_values << tag_value.to_s if tag_value.present?
end
end
tag_values.compact.flatten
end
module_function :build_tag_values
def tag_builder
@tag_builder ||= TagBuilder.new(self)
end

11
actionview/test/template/tag_helper_test.rb
View File

@ -338,6 +338,17 @@ class TagHelperTest < ActionView::TestCase
assert_equal "<p class=\"song play>\">limelight</p>", str
end
def test_class_names
assert_equal "song play", class_names(["song", { "play": true }])
assert_equal "song", class_names({ "song": true, "play": false })
assert_equal "song", class_names([{ "song": true }, { "play": false }])
assert_equal "song", class_names({ song: true, play: false })
assert_equal "song", class_names([{ song: true }, nil, false])
assert_equal "song", class_names(["song", { foo: false }])
assert_equal "song play", class_names({ "song": true, "play": true })
assert_equal "", class_names({ "song": false, "play": false })
end
def test_content_tag_with_data_attributes
assert_dom_equal '<p data-number="1" data-string="hello" data-string-with-quotes="double&quot;quote&quot;party&quot;">limelight</p>',
content_tag("p", "limelight", data: { number: 1, string: "hello", string_with_quotes: 'double"quote"party"' })