how to customize rails activerecord validation error message to show attribute value

Question

When a user tries to create a record with a name that already exists, I want to show an error message like:

name \"some name\" has already been taken

Answer 1

It looks like you can pass a Proc to the message. When you do this, you get two parameters:

1. A symbol along the lines of :activerecord.errors.models.user.attributes.name.taken
2. A hash that looks something like `{:model=>"User", :attribute=>"Name", :value=>"My Name"}

So if you allow for two parameters on a proc, you can use the attributes[:value] item to get the name that was used:

validates_uniqueness_of :name, 
                        :message => Proc.new { |error, attributes| 
                          "#{attributes[:value]} has already been taken." 
                        }