Here's an example of how to do it: http://google3/experimental/users/acozzette/map_reflection_test.cc?rcl=158157727 It's a bit clunky because you just have to reflect on the map field like you would a repeated field, but it works.
On Mon, Jun 5, 2017 at 6:08 PM, Qian Zhang <[email protected]> wrote: > Thanks Adam. > > Can you please let me know which API I can use to do reflection on a map? > > > Regards, > Qian Zhang > > On Mon, Jun 5, 2017 at 11:42 PM, Adam Cozzette <[email protected]> > wrote: > >> Doing reflection on a map is a little bit tricky, but the way to do it is >> to treat it as a repeated field since that is how it is actually >> represented on the wire. A map is a stored as a repeated message field, >> where in each message the key is field 1 and the value is field 2. >> >> On Mon, Jun 5, 2017 at 1:37 AM, Qian Zhang <[email protected]> wrote: >> >>> Hi Adam, >>> >>> We are using picojson <https://github.com/kazuho/picojson> to parse the >>> JSON file. >>> >>> After more debugging, I think I have found the root cause: In the code >>> here >>> <https://github.com/apache/mesos/blob/1.2.0/3rdparty/stout/include/stout/protobuf.hpp#L575>, >>> we are trying to find a field by the key of an entry in a map, obviously it >>> will fail since the key of any map entries is not in the protobuf message >>> definition (the .proto file), and to avoid finding field by a map entry's >>> key, in this method >>> <https://github.com/apache/mesos/blob/1.2.0/3rdparty/stout/include/stout/protobuf.hpp#L387:L407>, >>> we need to check if "field->is_map()" is true which is currently missed, if >>> the field is a map, then we should use the reflection to construct a map >>> message, however I do not find a method in protobuf to do that, I find a >>> lot of "Addxxx()" methods (e.g., "AddString()", "AddInt64()", etc.), but >>> not a method for adding a map. There is a method >>> "InsertOrLookupMapValue()", but that is a private method which I can not >>> call in my code. >>> >>> So can you please suggest how to add a map message? Thanks! >>> >>> >>> Regards, >>> Qian Zhang >>> >>> On Sat, Jun 3, 2017 at 1:02 AM, Adam Cozzette <[email protected]> >>> wrote: >>> >>>> It looks to me like your JSON syntax is right. Could you post the C++ >>>> code you are using to parse the JSON file? >>>> >>>> On Fri, Jun 2, 2017 at 1:16 AM, Qian Zhang <[email protected]> wrote: >>>> >>>>> Hi, >>>>> >>>>> I have a C++ project in which there is a .proto file, and in that >>>>> file, there is protobuf message which has a map field: >>>>> "map<string, string> annotations = 5;" >>>>> >>>>> And the JSON file to be parsed with that .proto file has the following >>>>> content: >>>>> "annotations": { >>>>> "com.example.key1": "value1", >>>>> "com.example.key2": "value2" >>>>> } >>>>> >>>>> The .proto file is in proto2 syntax (it has "syntax = "proto2";" at >>>>> the beginning) and I am using protobuf-3.3.0, the compilation succeed, but >>>>> I found the annotation map always has only one entry, and both the entry's >>>>> key and value are "" which is obviously not correct. >>>>> >>>>> Any suggestions? >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Protocol Buffers" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To post to this group, send email to [email protected]. >>>>> Visit this group at https://groups.google.com/group/protobuf. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>> >> > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/protobuf. For more options, visit https://groups.google.com/d/optout.
