What is the best way to filter a collection of objects pulled from a
database before display? I can think of 3 and have run into problems
with each:
1) Using SQL :joins and :conditions on Model.find. Problems: SQL is
ugly and the attributes coming back on my objects are being overwritten
(the ids that I need to pass to edit and delete actions are coming back
as the ids of the last table joined, not the ids of the objects I'm
requesting).
2) Use Model.find(:all) then iterate through the collection (for
@object in @objects) to remove the ones that don't meet my criteria.
Problem: I use @objects.delete(@object) to remove the unwanted objects
from the collection, but it seems that (for @object in @objects) has
some kind of internal counter and deleting an object from the
collection shortens the collection by 1 so that the next iteration
through @objects ends up skipping an object--in other words, if I were
trying to delete all the objects, only every OTHER object would be
deleted.
3) Use Model.find(:all) then filter each object in the view. Problem:
This logic shouldn't be in the view, though at this point it's the only
way I know I can get it to work.
What is the best way to filter a collection of objects pulled from a
database before display? I can think of 3 and have run into problems
with each:
1) Using SQL :joins and :conditions on Model.find. Problems: SQL is
ugly and the attributes coming back on my objects are being overwritten
(the ids that I need to pass to edit and delete actions are coming back
as the ids of the last table joined, not the ids of the objects I'm
requesting).
2) Use Model.find(:all) then iterate through the collection (for
@object in @objects) to remove the ones that don't meet my criteria.
Problem: I use @objects.delete(@object) to remove the unwanted objects
from the collection, but it seems that (for @object in @objects) has
some kind of internal counter and deleting an object from the
collection shortens the collection by 1 so that the next iteration
through @objects ends up skipping an object--in other words, if I were
trying to delete all the objects, only every OTHER object would be
deleted.
3) Use Model.find(:all) then filter each object in the view. Problem:
This logic shouldn't be in the view, though at this point it's the only
way I know I can get it to work.
Any help is appreciated,
Isaac
The easiest way sort of depends on what you are doing, so an example
would be helpful.
In general #1 is your best approach. Just don't retrieve records you
don't need.
#2 won't scale. If you have more than a few objects in your table, you
end up creating them all, which chews up memory and slows down the
server.
#3 has the same problem in addition to doing business logic in a
view...
In general, something like..
Model.find(:all, :conditions=>["user = ?", user_id])
or
model.users
(if you have your associations set up right)
