Added support for hybrid search

Author: ankane

lib/searchkick/query.rb

@@ -529,14 +529,10 @@ def prepare
       # knn
       knn = options[:knn]
       if knn
-        if term != "*"
-          raise ArgumentError, "Hybrid search not supported yet"
-        end
-
         field = knn[:field]
         vector = knn[:vector]
         k = per_page + offset
-        filter = payload.delete(:query)
+        filter = term == "*" ? payload.delete(:query) : payload[:query]
 
         if Searchkick.opensearch?
           payload[:query] = {

test/hybrid_test.rb

@@ -0,0 +1,17 @@
+require_relative "test_helper"
+
+class HybridTest < Minitest::Test
+  def setup
+    skip unless Searchkick.knn_support?
+    super
+  end
+
+  def test_basic
+    store [
+      {name: "Product A", embedding: [1, 2, 3]},
+      {name: "Item B", embedding: [1, 2, 3]},
+      {name: "Product C", embedding: [-1, -2, -3]}
+    ]
+    assert_order "product", ["Product A", "Product C"], knn: {field: :embedding, vector: [1, 2, 3]}
+  end
+end