Newbie: 'find' across multiple relationships

Rails
1

For security purposes, I often want to find objects that are ‘visible’.

e.g.

class Person < ActiveRecord::Base
has_many :x
end

…

@person.x.find(params[:id]) as opposed to X.find([params[:id]). Simple
enough for me.

My question:

Say we have -

class Person < ActiveRecord::Base
has_many :x, :class_name ‘Z’, …
has_many :y, :class_name ‘Z’, …
end

In other words, two different associations for the same type of model.
Maybe the second collection is a habtm, etc.

What is the best technique for doing a find on the union of those
collections? I can think of a half dozen ways, but none of them seem
‘idiomatic’.

Thanks

2

Am Donnerstag, den 23.03.2006, 02:07 +0100 schrieb John S.:

@person.x.find(params[:id]) as opposed to X.find([params[:id]). Simple

In other words, two different associations for the same type of model.
Maybe the second collection is a habtm, etc.

What is the best technique for doing a find on the union of those
collections? I can think of a half dozen ways, but none of them seem
‘idiomatic’.

What about:

@person.x.find(params[:id]) || @person.y.find(params[:id])

–
Norman T.

http://blog.inlet-media.de

3

Norman T. wrote:

Am Donnerstag, den 23.03.2006, 02:07 +0100 schrieb John S.:

@person.x.find(params[:id]) as opposed to X.find([params[:id]). Simple

In other words, two different associations for the same type of model.
Maybe the second collection is a habtm, etc.

What is the best technique for doing a find on the union of those
collections? I can think of a half dozen ways, but none of them seem
‘idiomatic’.

What about:

@person.x.find(params[:id]) || @person.y.find(params[:id])

–
Norman T.

http://blog.inlet-media.de

Doesn’t find throw RecordNotFound (as opposed to returning nil or an
empty collection)?.

In any case, I don’t think it would produce the desired effect as I want
a collection that contains all the results from both associations in the
case where both have results.

Right now I’ve just defined a method in the model that uses a custom
conditional to find to OR the different possibilities. Maybe that’s a
reasonable approach.

4

Am Donnerstag, den 23.03.2006, 16:42 +0100 schrieb John S.:

What about:

@person.x.find(params[:id]) || @person.y.find(params[:id])

Doesn’t find throw RecordNotFound (as opposed to returning nil or an
empty collection)?.

In any case, I don’t think it would produce the desired effect as I want
a collection that contains all the results from both associations in the
case where both have results.

You are right:

(@person.x.find(params[:id]) rescue nil) || @person.y.find(params[:id])

–
Norman T.

http://blog.inlet-media.de