Polymorphic URL helpers are methods for smart resolution to a named route call when given an Active Record model instance. They are to be used in combination with ActionController::Resources.
These methods are useful when you want to generate correct URL or path to a RESTful resource without having to know the exact type of the record in question.
Nested resources and/or namespaces are also supported, as illustrated in the example:
polymorphic_url([:admin, @article, @comment])
results in:
admin_article_comment_url(@article, @comment)
Usage within the framework
Polymorphic URL helpers are used in a number of places throughout the Rails framework:
- url_for, so you can use it with a record as the argument, e.g. url_for(@article);
- ActionView::Helpers::FormHelper uses polymorphic_path, so you can write form_for(@article) without having to specify :url parameter for the form action;
- redirect_to (which, in fact, uses url_for) so you can write redirect_to(post) in your controllers;
- ActionView::Helpers::AtomFeedHelper, so you don‘t have to explicitly specify URLs for feed entries.
Prefixed polymorphic helpers
In addition to polymorphic_url and polymorphic_path methods, a number of prefixed helpers are available as a shorthand to :action => "…" in options. Those are:
- edit_polymorphic_url, edit_polymorphic_path
- new_polymorphic_url, new_polymorphic_path
- formatted_polymorphic_url, formatted_polymorphic_path
Example usage:
edit_polymorphic_path(@post) # => "/posts/1/edit" formatted_polymorphic_path([@post, :pdf]) # => "/posts/1.pdf"
Returns the path component of a URL for the given record. It uses polymorphic_url with :routing_type => :path.
[ show source ]
# File vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb, line 117
117: def polymorphic_path(record_or_hash_or_array, options = {})
118: options[:routing_type] = :path
119: polymorphic_url(record_or_hash_or_array, options)
120: end
Constructs a call to a named RESTful route for the given record and returns the resulting URL string. For example:
# calls post_url(post) polymorphic_url(post) # => "http://example.com/posts/1" polymorphic_url([blog, post]) # => "http://example.com/blogs/1/posts/1" polymorphic_url([:admin, blog, post]) # => "http://example.com/admin/blogs/1/posts/1" polymorphic_url([user, :blog, post]) # => "http://example.com/users/1/blog/posts/1"
Options
- :action - Specifies the action prefix for the named route: :new, :edit, or :formatted. Default is no prefix.
- :routing_type - Allowed values are :path or :url. Default is :url.
Examples
# an Article record polymorphic_url(record) # same as article_url(record) # a Comment record polymorphic_url(record) # same as comment_url(record) # it recognizes new records and maps to the collection record = Comment.new polymorphic_url(record) # same as comments_url()
[ show source ]
# File vendor/rails/actionpack/lib/action_controller/polymorphic_routes.rb, line 74
74: def polymorphic_url(record_or_hash_or_array, options = {})
75: if record_or_hash_or_array.kind_of?(Array)
76: record_or_hash_or_array = record_or_hash_or_array.compact
77: record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1
78: end
79:
80: record = extract_record(record_or_hash_or_array)
81: format = extract_format(record_or_hash_or_array, options)
82: namespace = extract_namespace(record_or_hash_or_array)
83:
84: args = case record_or_hash_or_array
85: when Hash; [ record_or_hash_or_array ]
86: when Array; record_or_hash_or_array.dup
87: else [ record_or_hash_or_array ]
88: end
89:
90: inflection =
91: case
92: when options[:action].to_s == "new"
93: args.pop
94: :singular
95: when record.respond_to?(:new_record?) && record.new_record?
96: args.pop
97: :plural
98: else
99: :singular
100: end
101:
102: args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
103: args << format if format
104:
105: named_route = build_named_route_call(record_or_hash_or_array, namespace, inflection, options)
106:
107: url_options = options.except(:action, :routing_type, :format)
108: unless url_options.empty?
109: args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options
110: end
111:
112: __send__(named_route, *args)
113: end