c# - protobuf-net use a string type as surrogate -

i trying serialize protobuf format c# class has properties on domain specific types. these types should handled value types.

i using protobuf.net.

an example

[protocontract] public class testclass {     [protomember(1)]     public string stringproperty { get; set; }      [protomember(2)]     public domaintypetobehandldedasstring domaintypetobehandldedasstring { get; set; } }  public class domaintypetobehandldedasstring {     public string value { get; set; }      public static implicit operator string(domaintypetobehandldedasstring domaintype)     {         return domaintype?.value;     }      public static implicit operator domaintypetobehandldedasstring(string s)     {         return new domaintypetobehandldedasstring {value = s};     } } 

in serialized message not want people care domaintypetobehandldedasstring. want them see string , send string.

so tried doing this:

var model = protobuf.meta.runtimetypemodel.default; model.add(typeof(domaintypetobehandldedasstring), false).setsurrogate(typeof(string)); 

but fails exception:

system.argumentexception: 'repeated data (a list, collection, etc) has inbuilt behaviour , cannot used surrogate' 

is there way specify custom serializer such class? , should said there domain types should treated int or other value types. not string.

thanks

edit

i tried in addition:

[protocontract] public class testclass {     [protomember(1)]     public string stringproperty { get; set; }      public domaintypetobehandldedasint domaintypetobehandldedasint { get; set; } }  [protocontract] public class domaintypetobehandldedasint : iconvertible {     [protomember(1)]     public int value { get; set; }      public static implicit operator int(domaintypetobehandldedasint domaintype)     {         return domaintype?.value ?? 0;     }      public static implicit operator domaintypetobehandldedasint(int s)     {         return new domaintypetobehandldedasint { value = s };     }      public int toint32(iformatprovider provider)     {         return value;     }      //all rest throw notimplementedexception } 

i added type runtimemodel this:

var model = protobuf.meta.runtimetypemodel.default; model[typeof(testclass)].add(2, "domaintypetobehandldedasint", typeof(int32), null); 

and resulted in .proto file this:

syntax = "proto3"; package protobufferserializertest;  message testclass {    string stringproperty = 1;    repeated int32 domaintypetobehandldedasint = 2 [packed = false]; } 

but not want repeated , don't need [packed = false] either.

that's interesting question. @ moment, answer "no, isn't supported", but: following is supported, if enable allowparseabletypes (on runtimetypemodel instance - runtimetypemodel.default instance behind serializer.* methods):

public class domaintypetobehandldedasstring {     public string value { get; set; }     public override string tostring() => value;     public static domaintypetobehandldedasstring parse(string s)         => new domaintypetobehandldedasstring { value = s }; } 

basically, looks public static {type} parse(string) pattern. but: agree better express explicitly, , "surrogate string" nice way convey this. open adding direct support have in question, isn't there today , need code changes. not many, probably, since essentials of feature exist via parseable-types!

here's parseable-types approach working in example should work today:

using protobuf; using protobuf.meta;  public class domaintypetobehandldedasstring {     public string value { get; set; }     public override string tostring() => value;     public static domaintypetobehandldedasstring parse(string s)         => new domaintypetobehandldedasstring { value = s }; } [protocontract] public class bar {     [protomember(1)]     public domaintypetobehandldedasstring { get; set; } } class program {     static void main()     {         runtimetypemodel.default.allowparseabletypes = true;         var obj = new bar { = new domaintypetobehandldedasstring { value = "abcdef" } };         var clone = serializer.deepclone(obj);         system.console.writeline(clone.a.value);     } }