On Nov 7, 2011, at 10:40 AM, [email protected] wrote:
> I've been following [this tutorial][1] to try and get things working
> but still cannot get it sorted.
>
> Relationships are as follows:
>
> Radcheck have and belong to many Groups through Radusergroup
> Groups have and belong to many Radcheck through Radusergroup
>
> I have this in my models:
>
> class Radcheck
> include DataMapper::Resource
>
> has n, :radgroups, :model => 'Group', :child_key =>
> [:groupname], :parent_key => [:username], :through => :radusergroup
>
> end
The relationship to be traversed has to be defined before defining the
`:through` relationship. In other words:
``` ruby
class Radcheck
include DataMapper::Resource
property :id, Serial
property :name, String
has n, :radusergroups, :child_key => [:username], :parent_key => [:name]
has n, :radgroups, :through => :radusergroups
end
class Group
include DataMapper::Resource
property :id, Serial
property :name, String
has n, :radusergroups, :child_key => [:groupname], :parent_key => [:name]
has n, :radusers, :through => :radusergroups, :model => 'Radcheck'
end
class Radusergroup
include DataMapper::Resource
belongs_to :radusers, :model => 'Radcheck', :child_key => [:username],
:parent_key => [:name]
belongs_to :radgroups, :model => 'Group', :child_key => [:groupname],
:parent_key => [:name]
end
```
The `property` declarations in `Radcheck` and `Group` are, of course, at your
discretion, but you will need to specify the key mapping in the relationship
definitions (though not in the :through relationship definitions, since
:through relationships reflect on the existing relationships that they
traverse).
Hope that helps,
Emmanuel
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