RecordIdentifier
encapsulates methods used by various ActionView
helpers to associate records with DOM elements.
Consider for example the following code that form of post:
<%= form_for(post) do |f| %>
<%= f.text_field :body %>
<% end %>
When post
is a new, unsaved ActiveRecord::Base
instance, the resulting HTML is:
<form class="new_post" id="new_post" action="/posts" accept-charset="UTF-8" method="post">
<input type="text" name="post[body]" id="post_body" />
</form>
When post
is a persisted ActiveRecord::Base
instance, the resulting HTML is:
<form class="edit_post" id="edit_post_42" action="/posts/42" accept-charset="UTF-8" method="post">
<input type="text" value="What a wonderful world!" name="post[body]" id="post_body" />
</form>
In both cases, the id
and class
of the wrapping DOM element are automatically generated, following naming conventions encapsulated by the RecordIdentifier
methods dom_id
and dom_class
:
dom_id(Post.new) # => "new_post"
dom_class(Post.new) # => "post"
dom_id(Post.find 42) # => "post_42"
dom_class(Post.find 42) # => "post"
Note that these methods do not strictly require Post
to be a subclass of ActiveRecord::Base
. Any Post
class will work as long as its instances respond to to_key
and model_name
, given that model_name
responds to param_key
. For instance:
class Post
attr_accessor :to_key
def model_name
OpenStruct.new param_key: 'post'
end
def self.find(id)
new.tap { |post| post.to_key = [id] }
end
end
Constants
JOIN | = | "_" |
NEW | = | "new" |
Instance Public methods
dom_class(record_or_class, prefix = nil) Link
The DOM class convention is to use the singular form of an object or class.
dom_class(post) # => "post"
dom_class(Person) # => "person"
If you need to address multiple instances of the same class in the same view, you can prefix the dom_class
:
dom_class(post, :edit) # => "edit_post"
dom_class(Person, :edit) # => "edit_person"
dom_id(record, prefix = nil) Link
The DOM id convention is to use the singular form of an object or class with the id following an underscore. If no id is found, prefix with “new_” instead.
dom_id(Post.find(45)) # => "post_45"
dom_id(Post.new) # => "new_post"
If you need to address multiple instances of the same class in the same view, you can prefix the dom_id
:
dom_id(Post.find(45), :edit) # => "edit_post_45"
dom_id(Post.new, :custom) # => "custom_post"
Instance Private methods
record_key_for_dom_id(record) Link
Returns a string representation of the key attribute(s) that is suitable for use in an HTML DOM id. This can be overwritten to customize the default generated string representation if desired. If you need to read back a key from a dom_id
in order to query for the underlying database record, you should write a helper like ‘person_record_from_dom_id’ that will extract the key either based on the default implementation (which just joins all key attributes with ‘_’) or on your own overwritten version of the method. By default, this implementation passes the key string through a method that replaces all characters that are invalid inside DOM ids, with valid ones. You need to make sure yourself that your dom ids are valid, in case you override this method.