snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

examples/features/error_details/README.md

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+# Description
+
+This example demonstrates the use of status details in grpc errors.
+
+# Run the sample code
+
+Run the server:
+
+```sh
+$ go run ./server/main.go
+```
+Then run the client in another terminal:
+
+```sh
+$ go run ./client/main.go
+```
+
+It should succeed and print the greeting it received from the server.
+Then run the client again:
+
+```sh
+$ go run ./client/main.go
+```
+
+This time, it should fail by printing error status details that it received from the server.

examples/features/error_details/client/main.go

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+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Binary client demonstrates how to handle error messages from a gRPC server.
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"os"
+	"time"
+
+	epb "google.golang.org/genproto/googleapis/rpc/errdetails"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+	pb "google.golang.org/grpc/examples/helloworld/helloworld"
+	"google.golang.org/grpc/status"
+)
+
+var addr = flag.String("addr", "localhost:50052", "the address to connect to")
+
+func main() {
+	flag.Parse()
+
+	// Set up a connection to the server.
+	conn, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		log.Fatalf("did not connect: %v", err)
+	}
+	defer func() {
+		if e := conn.Close(); e != nil {
+			log.Printf("failed to close connection: %s", e)
+		}
+	}()
+	c := pb.NewGreeterClient(conn)
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	r, err := c.SayHello(ctx, &pb.HelloRequest{Name: "world"})
+	if err != nil {
+		s := status.Convert(err)
+		for _, d := range s.Details() {
+			switch info := d.(type) {
+			case *epb.QuotaFailure:
+				log.Printf("Quota failure: %s", info)
+			default:
+				log.Printf("Unexpected type: %s", info)
+			}
+		}
+		os.Exit(1)
+	}
+	log.Printf("Greeting: %s", r.Message)
+}

examples/features/error_details/server/main.go

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+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Binary server demonstrates how to provide error messages in gRPC responses.
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"sync"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	epb "google.golang.org/genproto/googleapis/rpc/errdetails"
+	pb "google.golang.org/grpc/examples/helloworld/helloworld"
+)
+
+var port = flag.Int("port", 50052, "port number")
+
+// server is used to implement helloworld.GreeterServer.
+type server struct {
+	pb.UnimplementedGreeterServer
+	mu    sync.Mutex
+	count map[string]int
+}
+
+// SayHello implements helloworld.GreeterServer
+func (s *server) SayHello(_ context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	// Track the number of times the user has been greeted.
+	s.count[in.Name]++
+	if s.count[in.Name] > 1 {
+		st := status.New(codes.ResourceExhausted, "Request limit exceeded.")
+		ds, err := st.WithDetails(
+			&epb.QuotaFailure{
+				Violations: []*epb.QuotaFailure_Violation{{
+					Subject:     fmt.Sprintf("name:%s", in.Name),
+					Description: "Limit one greeting per person",
+				}},
+			},
+		)
+		if err != nil {
+			return nil, st.Err()
+		}
+		return nil, ds.Err()
+	}
+	return &pb.HelloReply{Message: "Hello " + in.Name}, nil
+}
+
+func main() {
+	flag.Parse()
+
+	address := fmt.Sprintf(":%v", *port)
+	lis, err := net.Listen("tcp", address)
+	if err != nil {
+		log.Fatalf("failed to listen: %v", err)
+	}
+
+	s := grpc.NewServer()
+	pb.RegisterGreeterServer(s, &server{count: make(map[string]int)})
+	if err := s.Serve(lis); err != nil {
+		log.Fatalf("failed to serve: %v", err)
+	}
+}