Move ActionController::RecordIdentifier to ActionView

Since it's more about DOM classes and ids it belongs to Action View
better. What's more, it's more convenient to make it part of Action View
to follow the rule that Action Pack can depend on Action View, but not
the other way round.

1 files changed, 83 insertions, 0 deletions

diff --git a/actionpack/lib/action_view/record_identifier.rb b/actionpack/lib/action_view/record_identifier.rb
new file mode 100644
index 0000000000..0f4fc8aa75
--- /dev/null
+++ b/actionpack/lib/action_view/record_identifier.rb
@@ -0,0 +1,83 @@
+require 'active_support/core_ext/module'
+require 'action_controller/model_naming'
+
+module ActionView
+  # The record identifier encapsulates a number of naming conventions for dealing with records, like Active Records or
+  # pretty much any other model type that has an id. These patterns are then used to try elevate the view actions to
+  # a higher logical level.
+  #
+  #   # routes
+  #   resources :posts
+  #
+  #   # view
+  #   <%= div_for(post) do %>    <div id="post_45" class="post">
+  #     <%= post.body %>           What a wonderful world!
+  #   <% end %>                  </div>
+  #
+  #   # controller
+  #   def update
+  #     post = Post.find(params[:id])
+  #     post.update_attributes(params[:post])
+  #
+  #     redirect_to(post) # Calls polymorphic_url(post) which in turn calls post_url(post)
+  #   end
+  #
+  # As the example above shows, you can stop caring to a large extent what the actual id of the post is.
+  # You just know that one is being assigned and that the subsequent calls in redirect_to expect that
+  # same naming convention and allows you to write less code if you follow it.
+  module RecordIdentifier
+    extend self
+
+    include ModelNaming
+
+    JOIN = '_'.freeze
+    NEW = 'new'.freeze
+
+    # 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"
+    def dom_class(record_or_class, prefix = nil)
+      singular = model_name_from_record_or_class(record_or_class).param_key
+      prefix ? "#{prefix}#{JOIN}#{singular}" : singular
+    end
+
+    # 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"
+    def dom_id(record, prefix = nil)
+      if record_id = record_key_for_dom_id(record)
+        "#{dom_class(record, prefix)}#{JOIN}#{record_id}"
+      else
+        dom_class(record, prefix || NEW)
+      end
+    end
+
+  protected
+
+    # 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 overwrite this method.
+    def record_key_for_dom_id(record)
+      key = convert_to_model(record).to_key
+      key ? key.join('_') : key
+    end
+  end
+end