解组具有更改的嵌入类型的消息时出现未知字段错误

Question

给出这样的原型：

message Request {
    uint64 account_id = 1;
    message Foo{
        uint64 foo_id = 1;
    }
    repeated Foo foos = 2;

当我添加一个名为 bar_id

的字段时

message Request {
    uint64 account_id = 1;
    message Foo{
        uint64 foo_id = 1;
        uint64 bar_id = 2;
    }
    repeated Foo foos = 2;

通过 proto.UnmarshalText(msg, request) 使用旧 client 反序列化时出现错误。错误是 unknown field name "bar_id" in serviceA.Request_Foo.

我知道 proto-3 中的 unknown field 处理有很多变化，但这不是预期的，因为它似乎违反了前向兼容性（新服务器向旧客户端发送请求）。这与使用嵌入式类型有关吗？在不强制客户端更新的情况下更新服务器的最佳方法是什么？

Answer 1

您似乎在使用 github.com/golang/protobuf which is deprecated. Use google.golang.org/protobuf/encoding/prototext

UPD：使用DiscardUnknown

(prototext.UnmarshalOptions{DiscardUnknown: true}).Unmarshal(b, msg)

pb.proto:

syntax = "proto3";

// protoc --go_out=. *.proto

package pb;

option go_package = "./pb";

message RequestOld {
    uint64 account_id = 1;
    message Foo{
        uint64 foo_id = 1;
    }
    repeated Foo foos = 2;
}

message RequestNew {
    uint64 account_id = 1;
    message Foo{
        uint64 foo_id = 1;
        uint64 bar_id = 2;
    }
    repeated Foo foos = 2;
}

函数：

import "google.golang.org/protobuf/encoding/prototext"

// marshal old message
msgOld := &pb.RequestOld{
    AccountId: 1,
    Foos: []*pb.RequestOld_Foo{
        {
            FooId: 2,
        },
    },
}

log.Println("old:", msgOld.String())

bOld, err := prototext.Marshal(msgOld)
if err != nil {
    panic(err)
}

// unmarshal to new message
msgNew := &pb.RequestNew{}
if err := prototext.Unmarshal(bOld, msgNew); err != nil {
    panic(err)
}

log.Println("new:", msgNew.String())

输出：

2021/04/07 old: account_id:1  foos:{foo_id:2}
2021/04/07 new: account_id:1  foos:{foo_id:2}

解组具有更改的嵌入类型的消息时出现未知字段错误

Unknown field error when unmarshaling a message with changed embedded type

go

protocol-buffers

proto3