#143 ✓resolved
Dan Higham

Problem with belongs_to association model naming

Reported by Dan Higham | February 1st, 2008 @ 05:31 PM

It seems when a model has a belongs_to association to a foreign model where the foreign model ends in an "s" an error is raised when trying to use that association.

For example if you have a model called ticket and that ticket has an association to a model called status through a belongs_to association i.e

Class Ticket < DataMapper::Base

property :title, :string, :nullable => false

property :description, :text

belongs_to :status


Class Status

property :name, :string, :nullable => false


Calling the status property on the ticket causes the following error;

undefined method `to_sym' for nil:NilClass"

hope that makes sense!

Comments and changes to this ticket

  • asceth

    asceth February 1st, 2008 @ 09:52 PM

    Change your Ticket class to have:

    class Ticket < DataMapper::Base
    property :title, :string, :nullable => false
    property :description, :text
    belongs_to :status, :class => Status

    You probably want to put a has_many or has_one in the Status class as well:

    class Status
    property :name, :string, :nullable => false
    has_many :tickets

    The reason behind this is that in belongs_to the class name is passed through the inflector causing problems so defining it like I listed above fixes the problem. I believe afrench is adding this into the documentation to clarify it for future use.

  • Dan Higham

    Dan Higham February 2nd, 2008 @ 02:30 PM

    Works like a treat! I did add :class => 'Status' but this didn't work, how come it works by passing actual reference to the class itself?

  • asceth

    asceth February 3rd, 2008 @ 01:26 PM

    When you pass a String it still runs through the inflector which assigns the association_constant_name to Statu. Passing the actual reference does not go through the inflector and assigns it properly.

  • Adam French

    Adam French February 9th, 2008 @ 07:17 PM

    • State changed from “new” to “open”

    things working?

    can we close this bad boy out?

  • Nick Plante

    Nick Plante February 15th, 2008 @ 05:23 PM

    • State changed from “open” to “resolved”

    Working as described here. Pls reopen if you feel there is still an issue.

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