Write vector of struct with go

[mimu mimu]

Hello.

I have a problem with write vector of struct with Golang.

This is my fbs file definition.

namespace packets;

table User {

    uiid: string;

    name: string;

}

union PacketType {Ping, RoomInfo}

table Packet {

    packet: PacketType;

}

table Ping {

    timestamp: uint;

}

table RoomInfo {

    id: uint;

    users: [User];

}

root_type Packet;

This is my code write room info with c++

flatbuffers::FlatBufferBuilder builder;

auto user1 = CreateUser(builder, builder.CreateString("user1"), builder.CreateString("user1_uuid"));

auto user2 = CreateUser(builder, builder.CreateString("user2"), builder.CreateString("user2_uuid"));

flatbuffers::Offset<User> users[2];

users[0] = user1;

users[1] = user2;

auto vec = builder.CreateVector(users, 2);

RoomInfoBuilder rib(builder);

rib.add_id(100);

rib.add_users(vec);

auto packet = CreatePacket(builder, PacketType_RoomInfo, rib.Finish().Union());

builder.Finish(packet);

std::ofstream ofs("/tmp/roominfo.data", std::ios::out | std::ios::binary);

if (!ofs) {

    std::cout << "file open failed" << std::endl;

    return -1;

}

ofs.write((char*)builder.GetBufferPointer(), builder.GetSize());

ofs.close();

And I want to write RoomInfo with Golang.

This is Golang code i wrote without vector of struct.

builder := flatbuffers.NewBuilder(0)

// create user 1

packets.UserStart(builder)

packets.UserAddName(builder, builder.CreateString("user1"))

packets.UserAddUiid(builder, builder.CreateString("user1_uuid"))

user1 := packets.LoginEnd(builder)

builder.Finish(user1)

// create user 2

packets.UserStart(builder)

packets.UserAddName(builder, builder.CreateString("user2222"))

packets.UserAddUiid(builder, builder.CreateString("user2222_uuid"))

user2 := packets.LoginEnd(builder)

builder.Finish(user2)

/// write room info

packets.RoomInfoStart(builder)

packets.RoomInfoAddId(builder, 1000)

///

/// HOW to build vector of struct??

///

room := packets.RoomInfoEnd(builder)

builder.Finish(room)

packets.PacketStart(builder)

packets.PacketAddPacketType(builder, packets.PacketTypeRoomInfo)

packets.PacketAddPacket(builder, room)

p := packets.PacketEnd(builder)

builder.Finish(p)

ioutil.WriteFile("/tmp/roominfo.go.data", builder.Bytes[builder.Head():], os.FileMode(0644))

Please help me to complete this code.

[Wouter van Oortmerssen]

I'm not sure I follow the Go code, since it calls LoginEnd even though the table was started with UserStart. Also you call builder.Finish on each user, even though Builder.Finish is only intended for the root object (much like C++).

Besides that, constructing a vector works much like the example in the documentation, except that you have to call it with PrependUOffsetT instead of PrependByte.

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[mimu mimu]

Thank you for your response!

I've successfully completed my code like below.

builder := flatbuffers.NewBuilder(0)

// create user 1

packets.UserStart(builder)

packets.UserAddName(builder, builder.CreateString("user1"))

packets.UserAddUiid(builder, builder.CreateString("user1_uuid"))

user1 := packets.UserEnd(builder)

// create user 2

packets.UserStart(builder)

packets.UserAddName(builder, builder.CreateString("user2222"))

packets.UserAddUiid(builder, builder.CreateString("user2222_uuid"))

user2 := packets.UserEnd(builder)

// create vector

packets.RoomInfoStartUsersVector(builder, 2)

builder.PrependUOffsetT(user1)

builder.PrependUOffsetT(user2)

vec := builder.EndVector(2)

/// write room info

packets.RoomInfoStart(builder)

packets.RoomInfoAddId(builder, 1000)

packets.RoomInfoAddUsers(builder, vec)

room := packets.RoomInfoEnd(builder)

builder.Finish(room)

packets.PacketStart(builder)

packets.PacketAddPacketType(builder, packets.PacketTypeRoomInfo)

packets.PacketAddPacket(builder, room)

p := packets.PacketEnd(builder)

builder.Finish(p)

ioutil.WriteFile("/tmp/roominfo.go.data", builder.Bytes[builder.Head():], os.FileMode(0644))

[Wouter van Oortmerssen]

That looks better :)