Mongoid fields issue

Question

I am working on dynamic form generator. And I've noticed strange behaviour

class Model
  include Mongoid::Document
  field :name, :type => String
end

model = Model.new
model.name = "My Name"
model.surname = "My Surname"
#=> NoMethodError: undefined method `surname='

but

model = Model.new( :name => "My Name", :surname => "My Surname" )
#=> ok
model.surname
#=> "My Surname"
model.surname = "New Surname"
#=> "New Surname"

Can somebody explain why I can create new fields with mass assignment and can't add fields through attribute?

Dylan Markow · Accepted Answer · 2011-07-13 19:12:39Z

3

Per the Mongoid documentation, the getter/setter methods (e.g. .surname) will only work if the field exists in the document (which is why when you create a new Model with the field, it works).

You can still set/read the fields like so:

model[:surname]
model.read_attribute(:surname)
model[:surname] = "My Surname"
model.write_attribute(:surname, "My Surname")

See http://mongoid.org/docs/documents/dynamic.html

answered Jul 13, 2011 at 19:12

Dylan Markow

125k27 gold badges287 silver badges202 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

fl00r Over a year ago

that is the same functionality: model[:surname] = "My Surname" and model.write_attribute(:surname, "My Surname"). What is the difference? I've just tested - looks pretty same, but there is no comments in that docs article

Dylan Markow Over a year ago

The source code has alias :[] :read_attribute, so they are exactly the same (same with []= and write_attribute). Just use the one you prefer.

Collectives™ on Stack Overflow

Mongoid fields issue

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related