find query

rubyonrails-talk
1

Hi,

I have user table (last_activity, last_activity_at, ....) and friendships table (many to many). What I am trying to do is to show to the user the last actions of his/her friends.

[code]@activities = User.find_by_username(username, :order => 'last_activity_at DESC', :include => [:friendships => :friend])[/code]

[code]<%= render :partial => 'friends_activity', :collection => @activities.friendships %>[/code]

But the descending ordering is not working :frowning: What I am missing here? Cheers, Pete

2

Hi,

I have user table (last_activity, last_activity_at, ....) and friendships table (many to many). What I am trying to do is to show to the user the last actions of his/her friends.

[code]@activities = User.find_by_username(username, :order => 'last_activity_at DESC', :include => [:friendships => :friend])[/code]

[code]<%= render :partial => 'friends_activity', :collection => @activities.friendships %>[/code]

But the descending ordering is not working :frowning: What I am missing here? Cheers, Pete

That sort would have ordered the users (from the 'main' find) by
descending last_activity_at, not the associations (which are loaded
with a separate find)

Fred

3

That sort would have ordered the users (from the 'main' find) by descending last_activity_at, not the associations (which are loaded with a separate find)

Fred

Ohh I see, I was trying to sort friendships table, but there is no column last_activity_at. I guess that's it. :frowning: or is there a way to re-sort the data by last_activity_at ? Cheers

4

The old style include that did one big join would probably do that for you. Just to be sure - I'm assuming that friendships and friends are a self referential has many though relationship (ie back to users ?)

I'd write the above query like this: u = User.find_by_username ... u.friendships.find :all, :joins => :friends, :order => 'last_activity_at desc'

You could squish that down to one query, but you'll have to work out how it aliases the table names (I always have to look that one up)

Fred

5

I'd write the above query like this: u = User.find_by_username ... u.friendships.find :all, :joins => :friends, :order => 'last_activity_at desc'

Cheers Fred, this is the trick I was looking for. Petr