All my data lives in a SQL database behind a RESTful API. I'm having a heck of a time trying to understand how ExtJS' 'belongsTo' and 'hasMany' associations work. The name sound simple, but I cannot figure out what ExtJS is using properties like 'foreignKey', 'primaryKey', 'associationKey', etc. to actually mean.

Every table in my DB has a primary key, available in the JsonRest API as the 'id' property. Those that have foreign keys present the fk in records as a 'resource_uri' pointing to the related RESTful resource.

How does this work with ExtJS' terminology?

Given t1 and t2:
id(Primary Key) value
1 'foo'
2 'bar'

id (Primary Key) related (Foreign Key) value
1 2 'asdf'
2 1 'fdsa'

asking for '/api/t2/2/' gives me
{'meta': ..., 'objects': [{'id' : '2',  'related' : '/api/t1/1/', 'value' : 'fdsa', 'resource_uri' : '/api/t2/2/'}]}
I want my ExtJS Model (and its associated proxy and store) to know that it should fetch the 'id' and 'value' from the provided uri. What do I need to set my parameters to to accomplish this?

Note: I saw this discussion of the same topic:
I don't recommend using associations in real world projects. At least now. Instead use approach which is shown in your example: Model+Store+Filtering.
I am curious to know if anyone has actually used associations in real projects.