add indices_boost option support

README.md

@@ -168,6 +168,12 @@ boost_where: {user_id: {value: 1, factor: 100}} # default factor is 1000
 boost_where: {user_id: [{value: 1, factor: 100}, {value: 2, factor: 200}]}
 ```
 
+Boost indices when searching across more than one index
+
+```ruby
+indices_boost: { Animal => 1, Product => 200 }
+```
+
 [Conversions](#keep-getting-better) are also a great way to boost.
 
 ### Get Everything

lib/searchkick/query.rb

@@ -345,6 +345,9 @@ def prepare
         # order
         set_order(payload) if options[:order]
 
+        # indices_boost
+        set_boost_by_indices(payload)
+
         # filters
         filters = where_filters(options[:where])
         set_filters(payload, filters) if filters.any?
@@ -469,6 +472,19 @@ def set_boost_where(custom_filters, personalize_field)
       end
     end
 
+    def set_boost_by_indices(payload)
+      return unless options[:indices_boost]
+
+      indices_boost = options[:indices_boost].each_with_object({}) do |(key, boost), memo|
+        index = key.respond_to?(:searchkick_index) ? key.searchkick_index.name : key
+        # try to use index explicitly instead of alias: https://github.com/elasticsearch/elasticsearch/issues/4756
+        index_by_alias = Searchkick.client.indices.get_alias(index: index).keys.first
+        memo[index_by_alias || index] = boost
+      end
+
+      payload[:indices_boost] = indices_boost
+    end
+
     def set_suggestions(payload)
       suggest_fields = (searchkick_options[:suggest] || []).map(&:to_s)
 

test/boost_test.rb

@@ -141,4 +141,11 @@ def test_boost_by_distance_hash
     ]
     assert_order "san", ["San Francisco", "San Antonio", "San Marino"], boost_by_distance: {field: :location, origin: {lat: 37, lon: -122}, scale: "1000mi"}
   end
+
+  def test_boost_by_indices
+    store_names ["Rex"], Animal
+    store_names ["Rexx"], Product
+
+    assert_order "Rex", ["Rexx", "Rex"], {index_name: [Animal, Product], indices_boost: {Animal => 1, Product => 200}}, Store
+  end
 end