Many to Many ElasticSearch - Rails

Question

I'm using the elasticsearch-rails gem and I'm trying to search a model that has a many to many relationship with another model.

Here are my models:

Customer has_and_belongs_to_many :locations

Location has_and_belongs_to_many :customers

I understand that ES doesn't support Many to Many associations, so I believe that I should be able to index an array of the associated location id's with each customer document. I'm not sure how to do this. As a result, I want to be able to search the customer database and set filters so that I am only searching customers associated with specific locations.

I don't currently have any mappings in place. This is mainly where I need help.

Here is a query I built with a previous project that handled filtering properly for a product database. I want to do the same thing here except filter by the associated locations.

    filters = []
    #filters.push term: {"status":"Disabled"}  
    if !params[:product_type].blank?
      filters.push term: {"product_type":"#{params[:product_type]}"}   
    end 

    if !params[:category].blank?
      filters.push term: {"category":"#{params[:category]}"}   
    end 

    if !params[:brand].blank?
      filters.push term: {"brand":"#{params[:brand]}"}   
    end 

    if filters != nil
      @products = Product.search(
       query:{
         function_score:{
           query:{
             bool:{
               must:{
                 multi_match:{
                   fields: ['brand^10', '_all'],
                   query: "#{query}",
                   fuzziness: "AUTO"
                 }
               },

                 filter:{
                   bool:{
                     must:filters
                   }
                 }

             }
           },
           field_value_factor:{
              field: "popularity",
              modifier: "log1p",
              factor: 0.5

           },
           boost_mode: "sum"
         }
       })

Thanks in advance.