Tmp delete from activerecord

Rails
1

Hello,

This is the case:
A project has many users.
a project has an admin.

when I list the project users I don’t want to display the admin user so
what I tried was:

users = @project.users
users.delete(admin_user)

users.each { |u| {
…
}

but what happens is that the admin_user gets deleted from the project.
is there a way to do a temporary delete without activerecord acting upon
it and without having to check with an ‘if’ inside the for loop?

thanks

2

in your table you must have an field, that defines the role of the user.
either an bool flag like is_admin, that can be true or false or a
integer or string, with several states like admin, customer and so on.

with a is_admin flag:
users = @project.users.find_by_is_admin(false)

with an integer role (0=normal user, 1 = admin)
users = @project.users.find_by_role(0)

with a string role (“admin” = admin, “user” = user…)
users = @project.users.find_by_role(“user”)

3

Hello Thorsten,

Thanks for the reply.

I though of that suggestion but the problem is that there is a
“permissions” table in between user and project which keeps the ‘admin’
boolean.
Yes it can be queried as well but I thought that would be just
performance loss just to filter out one user.
Getting all users of a project and just subtracting the admin_user
(which I already have) seemed a better solution.

Is there really no way for this similar to the way i did it:
users = @project.users
users.delete(admin_user)
but then without actually deleting the record from DB?

Thanks

4

Very strange, as this should work just fine. I too would expect this
to perform an Array#delete, not an ActiveRecord::Base.delete, and
testing this in one of my projects worked fine.

Can you verify that the result of @project.users is indeed an array?

Jan

5

Hello Jan,

Thanks for the reply.

@project.users.class says it is an Array.

when I don’t do the ‘delete’ then the admin user does not get removed so
this shouldn’t be a problem in another part of my code.

strange indeed

6

hm, i see. you want to use the array delete function. i’m not sure, how
you could get the “old” one that was overwritten by ActiveRecord.

maybe you could use delete_if, as far as i know that’s not recycled by
Rails.

users.delete_if {|u| u == admin_user }

but since it has to go through the whole array and check every single
item, you could do it in the loop, as far as performance is concerned.

7

On 21 Apr 2008, at 10:45, Jan-Christian F. wrote:

Very strange, as this should work just fine. I too would expect this
to perform an Array#delete, not an ActiveRecord::Base.delete, and
testing this in one of my projects worked fine.

Can you verify that the result of @project.users is indeed an array?

It’s not an array, it’s an association proxy.

u = @project.users
u.delete(foo)

is the same as @projects.users.delete(foo) (indeed there would be some
very funky going on if it wasn’t).

In this case you could do something like
users_without_admin = @project.users.reject {|u| u == admin}
or of course arrange for admin not to be in @project.users in the
first place.

Fred

8

with a is_admin flag:
users = @project.users.find_by_is_admin(false)

find_all_by_is_admin!

9

Jiminy, I didn’t know that. And of course I tested it with a regular
finder, not with an association … my bad.

Thanks Fred!