Method on a collection in a model

Rails
1

I have a model (x) that has_many y. Is it possible to write a method
that says:
x.ys.some_method
I’m assuming you’d put it in the x class…but I’m not too sure where to
go from there.

TIA

2

On 17 Jan 2008, at 23:21, Luke G. wrote:

I have a model (x) that has_many y. Is it possible to write a method
that says:
x.ys.some_method
I’m assuming you’d put it in the x class…but I’m not too sure
where to
go from there.

There are 2 things that you might be interested in:

Association extensions, in a nutshell:
has_many :ys do
def some_method
end
end
You get some magic variables such as the owner of the association etc…

The other thing to note is that if you have

class Foo < ActiveRecord::Base
def self.some_method
end
end

and X has_many :foos, then you can call x.foos.some_method and
some_method will magically be scoped for you.

Fred

3

Frederick C. wrote:

On 17 Jan 2008, at 23:21, Luke G. wrote:

Association extensions, in a nutshell:
has_many :ys do
def some_method
end
end

This looks to be the most attractive option. In this method I want to
access each object in the collection though. How do you do that using
the above method. The only examples I’ve been able to find so far have
been to do with extending finder methods.

You get some magic variables such as the owner of the association etc…

The other thing to note is that if you have

class Foo < ActiveRecord::Base
def self.some_method
end
end

and X has_many :foos, then you can call x.foos.some_method and
some_method will magically be scoped for you.

This method didn’t exactly work as it was calling the method against
class. But I really want to do something against the objects within the
collection.

4

On 17 Jan 2008, at 23:48, Luke G. wrote:

This looks to be the most attractive option. In this method I want to
access each object in the collection though. How do you do that using
the above method. The only examples I’ve been able to find so far have
been to do with extending finder methods.

proxy_target gets you the target object.

Fred

5

Frederick C. wrote:

On 17 Jan 2008, at 23:48, Luke G. wrote:

This looks to be the most attractive option. In this method I want to
access each object in the collection though. How do you do that using
the above method. The only examples I’ve been able to find so far have
been to do with extending finder methods.

proxy_target gets you the target object.

Fred

Thats perfect.
So what I ended up doing was
in the model for x I had
has_many y do
proxy_target.collect { |n| n.to_z }
end

in the model for y, I had a method called to_z.

This method of doing things seems a bit messy since I’m declaring a
method within the has_many. Is there a neater way to do it?