How to set an extension field of the message by using reflection in protobuffer

user_14074474 0
Viewed 385

How to set an extension field of the message in protobuffer? The code is like this:

message Header {
    optional string name = 1;
    extensions 2 to 10; 
}
message PbDirectiveHeader {
    extend Header {
        optional string message_id = 2;
    }
}

    PbDirectiveHeader header_msg;
    std::cout << "header_msg des : " << header_msg.GetDescriptor() << std::endl;
    const google::protobuf::FieldDescriptor* message_id_dec = header_msg.GetDescriptor()->FindExtensionByName("message_id");
    if (message_id_dec != nullptr) {
        std::cout << "header_msg message_id's des containing_type: " << message_id_dec->containing_type() << std::endl;
        header_msg.GetReflection()->SetString(&header_msg, message_id_dec, "123456");
        std::cout << "message_id:" << header_msg.GetReflection()->GetString(header_msg, message_id_dec) << std::endl;
    } else {
        std::cout << "header_msg message_id des is nullptr" << std::endl;
    }

the error message is :

[libprotobuf FATAL google/protobuf/generated_message_reflection.cc:86] Protocol Buffer reflection usage error:
...
Problem     : Field does not match message type.

If I use reflection to set the name field of Header message, there is no error, but if I turn to set the extension field of message_id, the error happens again. how to solve my problem?

protocol-buffers
1 Answers

I find a solution to solve my problem

    PbDirectiveHeader header_msg;
    Header header;
    std::cout << "header_msg des : " << header_msg.GetDescriptor() << std::endl;
    const google::protobuf::FieldDescriptor* message_id_dec = header_msg.GetDescriptor()->FindExtensionByName("message_id");
    if (message_id_dec != nullptr) {
        std::cout << "header_msg message_id's des containing_type: " << message_id_dec->containing_type() << std::endl;
        header.GetReflection()->SetString(&header, message_id_dec, "123456");
        std::cout << "message_id:" << header.GetReflection()->GetString(header, message_id_dec) << std::endl;
    } else {
        std::cout << "headermessage_id des is nullptr" << std::endl;
    }

Use extension message to find an extension field, then use the base message to set/get the extension field's value.

user_140744740
Related