protobuf-net enum serialization

17
votes

What needs to be done in order to serialize enums with protobuf-net? I'm getting the below error when serializing a class having an enum property, if the DataMember attribute is removed from the property declaration it works fine.

"System.InvalidOperationException: Only data-contract classes (and lists/arrays of such) can be processed"

2
enumsprotocol-buffersprotobuf-net
Do you have an example? This should work fine... – Marc Gravell♦
Hello Marc! Thanks for post about deseriazing List<T> using Protobuf.net. I've got the same issue. I will post example below. – Andrew Kalashnikov
Just a heads up, this question is being discussed on meta. Is there a reason you rolled back the edit including an MCVE? Was your situation different from Andrews? – Rob♦

2 Answers

18
votes

I suspect they are actually 2 different scenarios, but with regard to the code sample added by Andrew, this is because it can't figure out (in advance) what it is going to do with regards to default values (by default, data is treated as optional at the receiver). There are 3 ways of fixing this:

1: add an enum with value 0 (since 0 is always the CLI default value for zeros), for example

public enum SiteType
{
    Error = 0,
    ...

2: tell it which value to use by default:

[ProtoMember(10), DefaultValue(SiteType.Partition)]
public SiteType Type { get; set; }

3: tell the engine that it really doesn't need to worry about it, i.e. that it is going to have a value:

[ProtoMember(10, IsRequired = true)]
public SiteType Type { get; set; }
4
votes

Sample:

[DataContract]
[ProtoContract]
public enum SiteType
{
    [EnumMember]
    [ProtoEnum]
    Site = 1,
    [EnumMember]
    [ProtoEnum]
    Partition = 2,
    [EnumMember]
    [ProtoEnum]
    Module = 3
}

[DataContract]
[Serializable]
[ProtoContract]
public class SiteDTO
{
    [DataMember]
    [ProtoMember(1)]
    public int Id { get; set; }
    ...
    [DataMember]
    [ProtoMember(10)]
    public SiteType Type { get; set; }
}