why all generated file is pointer field about protobuf HOT 4 CLOSED

That's how the proto2 API works. Read the package docs. proto3 might suit you better if you don't want pointers.

from protobuf.

You mean my generator is used proto2? or my proto file write in proto2 format?

I installed the latest potobuf-gen-go via "go get -u github.com/golang/protobuf/protoc-gen-go"

And I run command

proto --go_out=../proto-gen msg.proto

from protobuf.

from protobuf.

Because proto2 has configs like required and optional while proto3 field are alway optional. In some cases in proto2, you need to know whether the optional field has been set to zero value manually or it's just an auto default value. With pointer, we can use nil to find out.

Sample Code:

m := &MsgErrCode{}
if m.Reason == nil {
     // the field not been set
} else if *m.Reason == "" {
    // the field has been set to "" manually
}

While the function func (m *MsgErrCode) GetReason() string in *.pb.go files will always return "".

More Info: protobuf/proto

from protobuf.