A Category has many Products
Why can't I pass arguments to the count or size method?
This works fine: category_obj.products.find(:all, :conditions => "price > 20")
Why cant I do the same with .count or .size?
This doesn't work category_obj.products.count(:conditions => "price > 20")
Neither does this category_obj.products.size(:conditions => "price > 20")
Any ideas how I can do this with out doing Products.count(args)?
Try...
category_obj.products.count("price > 20")
I don’t think that really makes sense since count returns an integer. Include includes associated things. AR objects aren’t associated with integers.
From api.rubyonrails.com:
category_obj.products.count(“id”, :conditions => “price > 20”, :include => :whatever)
True. In this situation then can you not use
category_obj.products.find( :all. :include => :whatever, :conditions => blah ).count
The problem I guess is that it instantiates all those AR objects.
The docs for count suggest that you should be able to include other objects. This is listed as a class method though and looks like it’s marked as depricated.
http://api.rubyonrails.org/classes/ActiveRecord/Calculations/ClassMethods.html#M000951
Instead you could use calculate
I believe you could use
category_obj.products.calculate( :count, :include => :whatever, :conditions => blah )
But failing that there’s always
count_by_sql
Sorri if this is off track.
The docs for count suggest that you should be able to include other objects. This is listed as a class method though and looks like it’s marked as depricated.
http://api.rubyonrails.org/classes/ActiveRecord/Calculations/ClassMethods.html#M000951
I missed that deprecation noticed. Wish it was bold. 
That’s what i get for skimming…
Ok I’ve just had a quick look at this. If this doesn’t work then I’ll have to wait a bit before I can explore it. The calculate method requires a column to be specified.
category_obj.products.calculate( :count, “*”, :include => :whatever, :conditions => “blah” )
I really should read the docs a little better 
The include option is not included in the calculate method. The sql error that I got was due to the included table not being included as a JOIN operation.
Instead you need to use the old school and verbose :join option
So in your case
category_obj.products.calculate( :count, “*”, :join => “LEFT JOIN whatevers ON whatever.product_id”, :conditions => blah )
Sorry But I can’t spend any more time on this at the moment. If it’s still a problem if someone else can step in or it’ll have to wait until I get home.
Cheers
It worked for you then?