protobuf messages are typeless. There is no difference between
message Foo {
int field = 1;
}
and
message Bar {
int otherfield = 1;
}
On Mon, Dec 22, 2014 at 1:32 PM, Ryan O'Meara
<[email protected]> wrote:
> Hi,
>
> I am using protobuf for a project, and I've run into an interesting case,
> which I've had no luck finding a standard solution to. For the record, I'm
> using the Java APIs to interact with my messages
>
> My project has several messages defined, a few of which have similar fields
> (for example, two of them have a required text field with index 1). The
> problem I'm running into is that if I erroneously pass the byte array form
> of one message to a builder of the other message, it will happily parse it
> without any exceptions or other issues. (Apparently
> InvalidProto....Exception is thrown only is the array is completely invalid
> as a protobuf message of any type, and does not indicate anything else)
>
> I have tried checking "isInitialized", but because they both have the same
> required fields at the same indexes, it doesn't have an error.
>
> I considered changing the indexes or something like that, but that depends
> on every person who works on this project knowing about and respecting that
> convention - which doesn't seem like a sustainable solution. I also thought
> of checking the unknown fields, but one of the reasons I chose protobuf was
> for its forward and backwards compatibility - and I believe that the unknown
> filed list will be (validly) non-empty if I add a field down the road and an
> old version of the project receives a new version of the message.
>
> The only other thing I can think to do is to add a field in my messages
> which indicates the message - is this my best option, or am I missing
> something in the standard libraries which handles this?
>
> Thanks!
>
> Example:
>
> message Message1 {
>
> required string field1 = 1;
>
> optional string field2 = 2;
> }
>
> message Message2 {
>
> required string field1 = 1;
>
> optional int32 field2 = 2;
>
> }
>
>
> public void parseMessage1(byte[] protobuf){
> try {
> Message1 message = Messag1e.parseFrom(protobuf);
>
> if(message.isInitialized()){
> //Do some stuff
> }else{
> //Never get here
> }
> } catch (InvalidProtocolBufferException e) {
> //Not thrown
> }
> }
>
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