Enum field encoding question

[Burak Kirazli]

Hello,

I am new to protobuf. 

I have a request message like that

message CommandRequest

{

    enum Code

    {

        RESET = 0;

        ERASE_APP = 2;

        ERASE_OTA = 3;

    }

    

    Code code = 1;

}

When I am trying to encode a request with zero value, i see that encoded size is zero. What will be exchanged?

    //Qt project

    CommandRequest req;

    req.set_code(CommandRequest_Code::CommandRequest_Code_RESET);

    qDebug() << req.ByteSizeLong() << endl;

    
    //Output of this code is:
    0

Thanks.

[Marc Gravell]

Hi; default values *are not sent*, especially in proto3 where zero is default and default is zero. Likewise, the root object in a message is not wrapped in any way - only fields *on* the root object.

This means that the binary encoding of a CommandRequest with Code.RESET is: zero bytes, which is a perfectly valid size in protobuf.

Sometimes, people find it convenient / helpful to use a DEFAULT / NONE / UNKNOWN = 0, with their *actual* enum values above that. This makes the default experience easier to understand, and avoid problems.

Marc

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Regards,

Marc

[Alexey Edelev]

Hi,

I think this project might be useful for you https://github.com/semlanik/qtprotobuf

четверг, 16 января 2020 г., 9:08:39 UTC+1 пользователь Burak Kirazli написал: