If you can just write code specific to your message type which deals with merging items with the same ID, I'd suggest doing that. If you really need to write a totally generic algorithm, you can use reflection as documented here: http://code.google.com/apis/protocolbuffers/docs/reference/cpp/google.protobuf.message.html#Reflection
On Fri, Aug 14, 2009 at 4:46 PM, George Georgiev <georgi.georg...@citrix.com > wrote: > Hi, > > MergeFrom sounds good. > > The only issue that I still will have is with the repeated fields. For > some of them I will have an Id attribute. So what I would like to achieve > is when I merge the messages instead of adding new partial message in the > list it to combine those of the repeated messages that have the same Id. > > >> custom algorithm based on reflection > I suppose this is what I need in this case. Could you please give me a bit > more information what you mean. > > Thanks > -George > > ------------------------------ > *From:* Kenton Varda [mailto:ken...@google.com] > *Sent:* Friday, August 14, 2009 2:01 PM > *To:* George Georgiev > *Cc:* Protocol Buffers > *Subject:* Re: combine protobuf messages > > On Fri, Aug 14, 2009 at 1:18 PM, George Georgiev < > georgi.georg...@citrix.com> wrote: > >> 1. How to serialize parts from the message without validation >> > > Use the "Partial" serialization and parsing methods, e.g. > SerializePartialToString() and ParsePartialFromString(). These do not check > required fields. > > >> 2. How to combine two parts. Or how to parse second part which may >> overlap some of the already existing parts >> > > Use MergeFrom(): > > MyMessage combined; > // Iterate over messages from lowest to highest priority. > for (int priority = 0; priority < max_priority; ++priority) { > combined.MergeFrom(messages_by_priority[priority]); > } > > // Check > if (!combined.IsInitialized()) { > cerr << "Missing required fields: " > << combined.InitializationErrorString() << endl; > return false; > } > > As documented, the semantics of MergeFrom() are: "Singular fields will be > overwritten, except for embedded messages which will be merged. Repeated > fields will be concatenated." > > So, if you merge the highest-priority message last, then its values will > end up taking precedence. > > If MergeFrom() isn't quite what you want, then you'll have to write a > custom algorithm based on reflection. > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To post to this group, send email to protobuf@googlegroups.com To unsubscribe from this group, send email to protobuf+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/protobuf?hl=en -~----------~----~----~----~------~----~------~--~---
