Thinking Sphinx - Sort order

Question

I have a requirement where I want to get results based on the order of IDs that i pass to sphinx:

I did sorting and filtering with ruby and then find order of user_ids to be

user_ids = [1, 3, 2]

Now, I want to apply search on top of this:

User.search_for_ids("Test", {:with => {:page => params[:page], :per_page => 25, :sphinx_internal_id => user_ids}, :sql => {:order => "field(id,#{user_ids.join(',')})"}})

I see that we can pass :sql => :order in options when we need to sort on sql. But that does not give me the result in the expected sorting order.

User.where(:id =>  [1, 2, 3]).order("field(id,#{user_ids.join(',')})") 

gives me proper results as expected

Please correct me if i am doing anything wrong here.Is there a way to preserve the order with respect to user_ids ? Any help is much appreciated.

Answer 1

I don't believe there is a built-in mechanism for a predetermined sort order, but you can sort after the search results are returned. Obviously this won't work well if you're using any sort of pagination:

user_ids = [1,3,2]
results = User.search_for_ids #...
results.sort_by {|result| user_ids.index(result.id) }

Answer 2

I know my fix isn't optimal but I wound up doing something like the code below. considering how "fast" sphinx is the overhead cost didn't seem too great. Zach's answer is fine, but i also needed to eager load several models

product_ids = Product.seach_for_ids(term)
products = Product.includes(:manufacturer, :images, :items).where(:id => product_ids).order("field(ID,#{product_ids.join(",")})")

And assuming you're using the will_paginate gem, you should be able to slap paginate at the end, because you'll have an arel object

products = Product.includes(:manufacturer, :images, :items).where(:id => product_ids).order("field(ID,#{product_ids.join(",")})").paginate