I have read this page quite thoroughly:
http://datamapper.org/docs/associations
If the answer is on there, it's simply not expressed in a way I can understand.
I'm very confused about using setting up relationship via Datamapper. The datamapper site above is pretty much all I can find on the topic, and as I've said, it hasn't been particularly helpful.
For example, if I want to create something like the following:
Table: users
id (primary key)
name
Table: attributes
id (pk)
title
Table: user_attributes
id (pk)
user_id (fk to users.id)
attribute_id (fk to attributes.id)
value
This seems simple enough, but it has been prohibitively difficult. Everything I try gives me errors like No relationships named user_attributes or user_attribute in UserUserAttribute (DataMapper::UnknownRelationshipError)
Can someone please tell me the class definitions for this simple mapping, and perhaps point me to a better discussion of DataMapper associations? Below is some of what I've tried.
class User
include DataMapper::Resource
property :id, Serial, :key => true
property :name, String
has n, :user_attributes, :through=>:attribute
end
class Attribute
include DataMapper::Resource
property :id, Serial, :key => true
property :name, String
has n, :user_attributes, :through=>:user
end
class UserAttribute
include DataMapper::Resource
belongs_to :user
belongs_to :attribute
end
I think you're seeing things like UserUserAttribute because DataMapper is trying to auto-generate an anonymous join class.
Here's an article that describes how to make named many-to-many relationships in DataMapper
You would probably change the example something like this: