2.9 KiB
2.9 KiB
Code Generation [Experimental]
We're experimenting with code generation to reduce the amount of boiler plate code written.
Example
Going from this
req := client.NewRequest("go.micro.srv.example", "Example.Call", &example.Request{
Name: "John",
})
rsp := &example.Response{}
if err := client.Call(context.Background(), req, rsp); err != nil {
return err
}
To
rsp, err := cl.Call(context.Background(), &example.Request{Name: "John"})
if err != nil {
return err
}
Generation of stub code for the example service
go get github.com/micro/protobuf/protoc-gen-go
cd examples/server/proto/example
protoc --go_out=plugins=micro:. example.proto
Look at examples/server/proto/example/example.pb.go to see the generated code.
Guide
Download the protoc-gen-go code
go get github.com/micro/protobuf/protoc-gen-go
Define your proto service.
hello.proto
syntax = "proto3";
// package name is used as the service name for discovery
// if service name is not passed in when initialising the
// client
package go.micro.srv.greeter;
service Say {
rpc Hello(Request) returns (Response) {}
}
message Request {
optional string name = 1;
}
message Response {
optional string msg = 1;
}
Note: Remember to set package name in the proto, it's used to generate the service for discovery.
Generate code
protoc --go_out=plugins=micro:. hello.proto
Generated code
// Client API for Say service
type SayClient interface {
Hello(ctx context.Context, in *Request) (*Response, error)
}
type sayClient struct {
c client.Client
serviceName string
}
func NewSayClient(serviceName string, c client.Client) SayClient {
if c == nil {
c = client.NewClient()
}
if len(serviceName) == 0 {
serviceName = "go.micro.srv.greeter"
}
return &sayClient{
c: c,
serviceName: serviceName,
}
}
func (c *sayClient) Hello(ctx context.Context, in *Request) (*Response, error) {
req := c.c.NewRequest(c.serviceName, "Say.Hello", in)
out := new(Response)
err := c.c.Call(ctx, req, out)
if err != nil {
return nil, err
}
return out, nil
}
// Server API for Say service
type SayHandler interface {
Hello(context.Context, *Request, *Response) error
}
func RegisterSayHandler(s server.Server, hdlr SayHandler) {
s.Handle(s.NewHandler(hdlr))
}
Use the client
import (
"fmt"
"golang.org/x/net/context"
"github.com/micro/go-micro/client"
hello "path/to/hello/proto"
)
func main() {
cl := hello.NewSayClient("go.micro.srv.greeter", client.DefaultClient)
// alternative initialisation
// cl := hello.NewSayClient("", nil)
rsp, err := cl.Hello(contex.Background(), &hello.Request{"Name": "John"})
if err != nil {
fmt.Println(err)
}
}