Find unused items

Rails
1

This works, but I am sure there is a better way todo this:

GET /posts/1/edit

def edit
@post = Post.find(params[:id])
# Find user galleries that have not been used in posts yet
usergalleries = Array.new
@post.user.galleries.each do |pug|
usergalleries << pug.id
end
userpostgalleries = Array.new
@post.user.posts.each do |pup|
userpostgalleries << pup.gallery_id
end
aug = usergalleries - userpostgalleries
@availableusergalleries = @post.user.galleries.find
(:all, :conditions => { :id => aug })
end

Any ideas?

Regards
Arwed

2

Quoting arwed [email protected]:

end

@post = Post.find(params[:id])

 @post = Post.find(params[:id], :include => {:user => [:galleries,

:posts]})

One database call instead of many. I think this is correct form, but

have no easy way to test it.

# Find user galleries that have not been used in posts yet

usergalleries = Array.new

@post.user.galleries.each do |pug|

usergalleries << pug.id

end

 user_galleries = @post.user.galleries.map{|pug| pug[:id]}

I find pug[:id] more reliable than pug.id; the latter in some contexts

is

interpreted as the Object id, instead of the primary key/ID from the

database and a deprecation warning is given.

userpostgalleries = Array.new

@post.user.posts.each do |pup|

userpostgalleries << pup.gallery_id

end

 user_post_galleries = @post.user.posts.map{|pup| pup.gallery_id}

 aug = usergalleries - userpostgalleries

@availableusergalleries = @post.user.galleries.find(:all,

:conditions =>
{ :id => aug })
@availableusergalleries = @post.user.galleries.find(aug)

ActiveRecord.find will take an array of IDs.

Another way that takes less memory (if speed is of more concern,
benchmark
both):

aug = @post.user.galleries.map{|pug| pug[:id]}
@post.user.posts.each{|pup| aug.delete(pup.gallery_id)}

@availableusergalleries = Gallery.find(aug)

HTH,
Jeffrey

3

Hi Jeffrey,

thanks a lot for your help.
You made my day!

Regards
Arwed