Provides methods to generate HTML tags programmatically both as a modern HTML5 compliant builder style and legacy XHTML compliant tags.
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BOOLEAN_ATTRIBUTES | = | %w(allowfullscreen async autofocus autoplay checked compact controls declare default defaultchecked defaultmuted defaultselected defer disabled enabled formnovalidate hidden indeterminate inert ismap itemscope loop multiple muted nohref noresize noshade novalidate nowrap open pauseonexit readonly required reversed scoped seamless selected sortable truespeed typemustmatch visible).to_set |
PRE_CONTENT_STRINGS | = | Hash.new { "" } |
TAG_PREFIXES | = | ["aria", "data", :aria, :data].to_set |
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 <![CDATA[
and end with (and may not contain) the string ]]>
.
cdata_section("<hello world>")
# => <![CDATA[<hello world>]]>
cdata_section(File.read("hello_world.txt"))
# => <![CDATA[<hello from a text file]]>
cdata_section("hello]]>world")
# => <![CDATA[hello]]]]><![CDATA[>world]]>
Returns an HTML block tag of type name
surrounding the content
. Add HTML attributes by passing an attributes hash to options
. Instead of passing the content as an argument, you can also use a block in which case, you pass your options
as the second parameter. Set escape to false to disable attribute value escaping. Note: this is legacy syntax, see tag
method description for details.
Options
The options
hash can be used with attributes with no value like (disabled
and readonly
), which you can give a value of true in the options
hash. You can use symbols or strings for the attribute names.
Examples
content_tag(:p, "Hello world!")
# => <p>Hello world!</p>
content_tag(:div, content_tag(:p, "Hello world!"), class: "strong")
# => <div class="strong"><p>Hello world!</p></div>
content_tag(:div, "Hello world!", class: ["strong", "highlight"])
# => <div class="strong highlight">Hello world!</div>
content_tag("select", options, multiple: true)
# => <select multiple="multiple">...options...</select>
<%= content_tag :div, class: "strong" do -%>
Hello world!
<% end -%>
# => <div class="strong">Hello world!</div>
# File actionview/lib/action_view/helpers/tag_helper.rb, line 301 def content_tag(name, content_or_options_with_block = nil, options = nil, escape = true, &block) if block_given? options = content_or_options_with_block if content_or_options_with_block.is_a?(Hash) tag_builder.content_tag_string(name, capture(&block), options, escape) else tag_builder.content_tag_string(name, content_or_options_with_block, options, escape) end end
Returns an escaped version of html
without affecting existing escaped entities.
escape_once("1 < 2 & 3")
# => "1 < 2 & 3"
escape_once("<< Accept & Checkout")
# => "<< Accept & Checkout"
Returns an HTML tag.
Building HTML tags
Builds HTML5 compliant tags with a tag proxy. Every tag can be built with:
tag.<tag name>(optional content, options)
where tag name can be e.g. br, div, section, article, or any tag really.
Passing content
Tags
can pass content to embed within it:
tag.h1 'All titles fit to print' # => <h1>All titles fit to print</h1>
tag.div tag.p('Hello world!') # => <div><p>Hello world!</p></div>
Content can also be captured with a block, which is useful in templates:
<%= tag.p do %>
The next great American novel starts here.
<% end %>
# => <p>The next great American novel starts here.</p>
Options
Use symbol keyed options to add attributes to the generated tag.
tag.section class: %w( kitties puppies )
# => <section class="kitties puppies"></section>
tag.section id: dom_id(@post)
# => <section id="<generated dom id>"></section>
Pass true
for any attributes that can render with no values, like disabled
and readonly
.
tag.input type: 'text', disabled: true
# => <input type="text" disabled="disabled">
HTML5 data-*
attributes can be set with a single data
key pointing to a hash of sub-attributes.
To play nicely with JavaScript conventions, sub-attributes are dasherized.
tag.article data: { user_id: 123 }
# => <article data-user-id="123"></article>
Thus data-user-id
can be accessed as dataset.userId
.
Data attribute values are encoded to JSON, with the exception of strings, symbols and BigDecimals. This may come in handy when using jQuery's HTML5-aware .data()
from 1.4.3.
tag.div data: { city_state: %w( Chicago IL ) }
# => <div data-city-state="["Chicago","IL"]"></div>
The generated attributes are escaped by default. This can be disabled using escape_attributes
.
tag.img src: 'open & shut.png'
# => <img src="open & shut.png">
tag.img src: 'open & shut.png', escape_attributes: false
# => <img src="open & shut.png">
The tag builder respects HTML5 void elements if no content is passed, and omits closing tags for those elements.
# A standard element:
tag.div # => <div></div>
# A void element:
tag.br # => <br>
Legacy syntax
The following format is for legacy syntax support. It will be deprecated in future versions of Rails.
tag(name, options = nil, open = false, escape = true)
It returns an empty HTML tag of type name
which by default is XHTML compliant. Set open
to true to create an open tag compatible with HTML 4.0 and below. Add HTML attributes by passing an attributes hash to options
. Set escape
to false to disable attribute value escaping.
Options
You can use symbols or strings for the attribute names.
Use true
with boolean attributes that can render with no value, like disabled
and readonly
.
HTML5 data-*
attributes can be set with a single data
key pointing to a hash of sub-attributes.
Examples
tag("br")
# => <br />
tag("br", nil, true)
# => <br>
tag("input", type: 'text', disabled: true)
# => <input type="text" disabled="disabled" />
tag("input", type: 'text', class: ["strong", "highlight"])
# => <input class="strong highlight" type="text" />
tag("img", src: "open & shut.png")
# => <img src="open & shut.png" />
tag("img", { src: "open & shut.png" }, false, false)
# => <img src="open & shut.png" />
tag("div", data: { name: 'Stephen', city_state: %w(Chicago IL) })
# => <div data-name="Stephen" data-city-state="["Chicago","IL"]" />
# File actionview/lib/action_view/helpers/tag_helper.rb, line 266 def tag(name = nil, options = nil, open = false, escape = true) if name.nil? tag_builder else name = ERB::Util.xml_name_escape(name) if escape "<#{name}#{tag_builder.tag_options(options, escape) if options}#{open ? ">" : " />"}".html_safe end end