How can I select a SUM in a query using Rails 3 / MetaSearch?

Question

I have a Rails 3 application where my model includes Owners and Properties, each Owner representing a person or institution that owns one or more properties.

I would like to be able to search my database (SQLite3) and return the results grouped by owner. For each group, I would like to display:

-The owner's name (I can do this easily) -The total number of properties belonging to this owner that meet the search conditions (i.e., a count). -The total value of all the properties counted in the previous column (i.e., a sum).

Owner has_many Properties, and Property belongs_to Owner. Also, "value" is an attribute for Property.

I am using the MetaSearch gem, and I can get it to return a collection of properties correctly. I can also get it to group the results by owner, but I can't figure out how to display the number of properties and their summed value.

Here is the code to return the list of properties:

@search = Property.group("owner_id").search(params[:search])

I have tried adding a .select to the chain like this:

@search = Property.select("SUM(value) as mysum").group("owner_id").search(params[:search])

But I can't access this sum when I try. Does anyone know of an efficient way of handling this situation?

Answer 1

I realize this is old, but it's high in google search results.

You can simply call sum. Looking at your example, the following is approx what you're looking for:

Property.where(SEARCH_VALUES).group(:owner_id).sum(:value)

http://guides.rubyonrails.org/active_record_querying.html#sum