Thank you for the response! I have tried to solve this problem with "new" optional feature, but it doesn't work with the repeated field (that can be solved using the wrapper which contains an optional field).
But I have found that the problem only happens when proto files have different package names. If they are the same - protoc will generate pointer in both cases (pointer to struct and array of pointers). I don't know if it is a bug, but we have a solution with wrappers and that is good news! On Thursday, 18 June 2020 19:41:37 UTC+3, Josh Humphries wrote: > > The simplest answer is to use syntax="proto2" for that. In proto3, it is > intentional that you cannot distinguish between absence and zero value for > scalar fields. > > However, a new "proto3 optional > <https://github.com/protocolbuffers/protobuf/blob/master/docs/implementing_proto3_presence.md>" > > feature is now available that allows this. It allows you to add the > "optional" keyword to a field, where you might otherwise have specified > "repeated". The feature is in a kind of beta. You must be using 3.12 of > protoc or newer and you must enable the feature via a flag: > --experimental_allow_proto3_optional. You also need to be using a very > recent protoc-gen-go (v1.22 or newer from the google.golang.org/protobuf > import > path, or v1.4.1 or newer from github.com/golang/protobuf). > > ---- > *Josh Humphries* > jh...@bluegosling.com <javascript:> > > > On Thu, Jun 18, 2020 at 11:30 AM Klim Sidorov <skn.g...@gmail.com > <javascript:>> wrote: > >> Hello! >> >> *The question is:* >> How can I make protoc generate a pointer to the value? >> >> *The problem:* >> I have 2 files in the root directory. >> I use Makefile to generate Go code from .proto files. >> >> But the *language* field in the Video struct is a value not a pointer to >> the value. >> And the *subtitles* field in the Video struct is an array of values not >> an array of pointers to the value. >> >> *video.pb.go* >> >> type Video struct { >> state protoimpl.MessageState >> sizeCache protoimpl.SizeCache >> unknownFields protoimpl.UnknownFields >> >> Id string `protobuf:"bytes,1,opt,name=id,proto3" >> json:"id,omitempty"` >> Title string `protobuf:"bytes,2,opt,name=title,proto3" >> json:"title,omitempty"` >> Languages language.ISO639_1 >> `protobuf:"varint,3,opt,name=languages,proto3,enum=language.ISO639_1" >> json:"languages,omitempty"` >> Subtitles []language.ISO639_1 >> `protobuf:"varint,4,rep,packed,name=subtitles,proto3,enum=language.ISO639_1" >> json:"subtitles,omitempty"` >> } >> >> >> >> *Makefile* >> >> gen: >> # Video >> protoc -I. --go_out=plugins=grpc,paths=source_relative:video video.proto >> >> # Language >> protoc -I. --go_out=plugins=grpc,paths=source_relative:language >> language.proto >> >> >> >> *language.proto* >> >> syntax = "proto3"; >> >> package language; >> >> option go_package = "example.com/group/repo/language;language"; >> >> enum ISO639_1 { >> UNKNOWN = 0; >> zh = 1; >> } >> >> >> >> *video.proto* >> >> >> syntax = "proto3"; >> >> package video; >> >> import "language.proto"; >> >> option go_package = "example.com/group/repo/video;video"; >> >> message Video { >> string id = 1; >> string title = 2; >> language.ISO639_1 language = 3; >> repeated language.ISO639_1 subtitles = 4; >> } >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Protocol Buffers" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to prot...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/protobuf/eac045ed-aceb-401c-a6ba-1de876c7bfdbo%40googlegroups.com >> >> <https://groups.google.com/d/msgid/protobuf/eac045ed-aceb-401c-a6ba-1de876c7bfdbo%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/protobuf/61becfd1-ce72-475f-843a-3836ca689784o%40googlegroups.com.
