enhance: [GoSDK] Support function reranker (#43845)

Related to #35856

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

client/milvusclient/read_option_test.go

@@ -52,7 +52,15 @@ func (s *SearchOptionSuite) TestBasic() {
 	topK := rand.Intn(100) + 1
 	opt := NewSearchOption(collName, topK, []entity.Vector{entity.FloatVector([]float32{0.1, 0.2})})
 
-	opt = opt.WithANNSField("test_field").WithOutputFields("ID", "Value").WithConsistencyLevel(entity.ClStrong).WithFilter("ID > 1000").WithGroupByField("group_field").WithGroupSize(10).WithStrictGroupSize(true)
+	rerankerFunction := entity.NewFunction().WithName("time_decay").WithInputFields("timestamp").WithType(entity.FunctionTypeRerank).
+		WithParam("reranker", "decay").
+		WithParam("function", "gauss").
+		WithParam("origin", 1754995249).
+		WithParam("scale", 7*24*60*60).
+		WithParam("offset", 24*60*60).
+		WithParam("decay", 0.5)
+
+	opt = opt.WithANNSField("test_field").WithOutputFields("ID", "Value").WithConsistencyLevel(entity.ClStrong).WithFilter("ID > 1000").WithGroupByField("group_field").WithGroupSize(10).WithStrictGroupSize(true).WithFunctionReranker(rerankerFunction)
 	req, err := opt.Request()
 	s.Require().NoError(err)
 
@@ -73,6 +81,9 @@ func (s *SearchOptionSuite) TestBasic() {
 	s.Require().True(ok)
 	s.Equal("true", spStrictGroupSize)
 
+	functionScore := req.GetFunctionScore()
+	s.Len(functionScore.GetFunctions(), 1)
+
 	opt = NewSearchOption(collName, topK, []entity.Vector{nonSupportData{}})
 	_, err = opt.Request()
 	s.Error(err)

client/milvusclient/read_options.go

@@ -79,6 +79,8 @@ type AnnRequest struct {
 	topK            int
 	offset          int
 	templateParams  map[string]any
+
+	functionRerankers []*entity.Function
 }
 
 func NewAnnRequest(annField string, limit int, vectors ...entity.Vector) *AnnRequest {
@@ -144,6 +146,13 @@ func (r *AnnRequest) searchRequest() (*milvuspb.SearchRequest, error) {
 		request.ExprTemplateValues[key] = tmplVal
 	}
 
+	if len(r.functionRerankers) > 0 {
+		request.FunctionScore = &schemapb.FunctionScore{}
+		for _, fr := range r.functionRerankers {
+			request.FunctionScore.Functions = append(request.FunctionScore.Functions, fr.ProtoMessage())
+		}
+	}
+
 	return request, nil
 }
 
@@ -277,6 +286,11 @@ func (r *AnnRequest) WithIgnoreGrowing(ignoreGrowing bool) *AnnRequest {
 	return r
 }
 
+func (r *AnnRequest) WithFunctionReranker(fr *entity.Function) *AnnRequest {
+	r.functionRerankers = append(r.functionRerankers, fr)
+	return r
+}
+
 func (opt *searchOption) Request() (*milvuspb.SearchRequest, error) {
 	request, err := opt.annRequest.searchRequest()
 	if err != nil {
@@ -358,6 +372,11 @@ func (opt *searchOption) WithSearchParam(key, value string) *searchOption {
 	return opt
 }
 
+func (opt *searchOption) WithFunctionReranker(fr *entity.Function) *searchOption {
+	opt.annRequest.WithFunctionReranker(fr)
+	return opt
+}
+
 func NewSearchOption(collectionName string, limit int, vectors []entity.Vector) *searchOption {
 	return &searchOption{
 		annRequest:                 NewAnnRequest("", limit, vectors...),
@@ -433,6 +452,7 @@ type hybridSearchOption struct {
 	limit             int
 	offset            int
 	reranker          Reranker
+	functionRerankers []*entity.Function
 }
 
 func (opt *hybridSearchOption) WithConsistencyLevel(cl entity.ConsistencyLevel) *hybridSearchOption {
@@ -461,6 +481,11 @@ func (opt *hybridSearchOption) WithReranker(reranker Reranker) *hybridSearchOpti
 	return opt
 }
 
+func (opt *hybridSearchOption) WithFunctionRerankers(functionReranker *entity.Function) *hybridSearchOption {
+	opt.functionRerankers = append(opt.functionRerankers, functionReranker)
+	return opt
+}
+
 func (opt *hybridSearchOption) WithOffset(offset int) *hybridSearchOption {
 	opt.offset = offset
 	return opt
@@ -485,7 +510,7 @@ func (opt *hybridSearchOption) HybridRequest() (*milvuspb.HybridSearchRequest, e
 		params = append(params, &commonpb.KeyValuePair{Key: spOffset, Value: strconv.FormatInt(int64(opt.offset), 10)})
 	}
 
-	return &milvuspb.HybridSearchRequest{
+	r := &milvuspb.HybridSearchRequest{
 		CollectionName:        opt.collectionName,
 		PartitionNames:        opt.partitionNames,
 		Requests:              requests,
@@ -493,7 +518,16 @@ func (opt *hybridSearchOption) HybridRequest() (*milvuspb.HybridSearchRequest, e
 		ConsistencyLevel:      commonpb.ConsistencyLevel(opt.consistencyLevel),
 		OutputFields:          opt.outputFields,
 		RankParams:            params,
-	}, nil
+	}
+
+	if len(opt.functionRerankers) > 0 {
+		r.FunctionScore = &schemapb.FunctionScore{}
+		for _, fr := range opt.functionRerankers {
+			r.FunctionScore.Functions = append(r.FunctionScore.Functions, fr.ProtoMessage())
+		}
+	}
+
+	return r, nil
 }
 
 func NewHybridSearchOption(collectionName string, limit int, annRequests ...*AnnRequest) *hybridSearchOption {