Methods
Instance Public methods
to_param(method_name = nil)
Defines your model’s to_param method to generate “pretty” URLs using method_name, which can be any attribute or method that responds to to_s.
class User < ActiveRecord::Base
to_param :name
end
user = User.find_by(name: 'Fancy Pants')
user.id # => 123
user_path(user) # => "/users/123-fancy-pants"
Values longer than 20 characters will be truncated. The value is truncated word by word.
user = User.find_by(name: 'David Heinemeier Hansson')
user.id # => 125
user_path(user) # => "/users/125-david-heinemeier"
Because the generated param begins with the record’s id, it is suitable for passing to find. In a controller, for example:
params[:id] # => "123-fancy-pants"
User.find(params[:id]).id # => 123
📝 Source code
# File activerecord/lib/active_record/integration.rb, line 147
def to_param(method_name = nil)
if method_name.nil?
super()
else
define_method :to_param do
if (default = super()) &&
(result = send(method_name).to_s).present? &&
(param = result.squish.parameterize.truncate(20, separator: /-/, omission: "")).present?
"#{default}-#{param}"
else
default
end
end
end
end