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

examples/features/error_handling/README.md

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+# Description
+
+This example demonstrates basic RPC error handling in gRPC.
+
+# Run the sample code
+
+Run the server, which returns an error if the RPC request's `Name` field is
+empty.
+
+```sh
+$ go run ./server/main.go
+```
+
+Then run the client in another terminal, which does two requests: one with an
+empty Name field and one with it populated with the current username provided by
+os/user.
+
+```sh
+$ go run ./client/main.go
+```
+
+It should print the status codes it received from the server.

examples/features/error_handling/client/main.go

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+/*
+ *
+ * Copyright 2023 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 errors returned by a gRPC server.
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+	"os/user"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"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()
+
+	name := "unknown"
+	if u, err := user.Current(); err == nil && u.Username != "" {
+		name = u.Username
+	}
+
+	// Set up a connection to the server.
+	conn, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		log.Fatalf("Failed to connect: %v", err)
+	}
+	defer conn.Close()
+	c := pb.NewGreeterClient(conn)
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	for _, reqName := range []string{"", name} {
+		log.Printf("Calling SayHello with Name:%q", reqName)
+		r, err := c.SayHello(ctx, &pb.HelloRequest{Name: reqName})
+		if err != nil {
+			if status.Code(err) != codes.InvalidArgument {
+				log.Printf("Received unexpected error: %v", err)
+				continue
+			}
+			log.Printf("Received error: %v", err)
+			continue
+		}
+		log.Printf("Received response: %s", r.Message)
+	}
+}

examples/features/error_handling/server/main.go

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+/*
+ *
+ * Copyright 2023 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 return specific error codes in gRPC
+// responses.
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	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
+}
+
+// SayHello implements helloworld.GreeterServer.
+func (s *server) SayHello(_ context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
+	if in.Name == "" {
+		return nil, status.Errorf(codes.InvalidArgument, "request missing required field: Name")
+	}
+	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{})
+	if err := s.Serve(lis); err != nil {
+		log.Fatalf("failed to serve: %v", err)
+	}
+}