I have an enum

public enum MyEnum : uint
    {
        ValueA = 1233104067,
        ValueB= 1119849093,
        ValueC= 2726580491
}

Whenever I create some class with this enum and try to store it into the database. For example

class MyClass {
    public MyEnum newValue = MyEnum.ValueC;
}

It will crash the program with this error

Unhandled Exception: System.OverflowException: Value was either too large or too small for an Int32.
   at System.Convert.ThrowInt32OverflowException()
   at System.UInt32.System.IConvertible.ToInt32(IFormatProvider provider)
   at MongoDB.Bson.Serialization.Serializers.EnumSerializer`1.Serialize(BsonSerializationContext context, BsonSerializationArgs args, TEnum value)

It tries to convert uint values to int, but they are too big and it throws exception.

How do I fix this problem?

Thanks.

MongoDB stores data as BSON, which doesn't have unsigned integer types.

You have three options:

1. Annotate your unsigned types.

   If using driver v2.4.3 or earlier:

   public class MyClass
   {
       [BsonRepresentation(BsonType.Int32, AllowOverflow = true)]
       public MyEnum Value1 = MyEnum.ValueC;
   
       [BsonRepresentation(BsonType.Int32, AllowOverflow = true)]
       public uint Value2 = uint.MaxValue;
   }
   

   Unfortunately the serializer in driver v2.4.4 and later doesn't respect AllowOverflow, throwing an exception anyway(tested and confirmed, thanks to dnickless for pointing this out). Here's a workaround (at the expense of some wasted space):

   public class MyClass
   {
       [BsonRepresentation(BsonType.Int64)]
       public MyEnum Value1 = MyEnum.ValueC;
   
       [BsonRepresentation(BsonType.Int64)]
       public uint Value2 = uint.MaxValue;
   }
   

2. Use signed types and convert where appropriate.

   // Defaults to int.
   public enum MyEnum
   {
       ValueA = 1233104067,
       ValueB = 1119849093,
       ValueC = unchecked((int)2726580491)
   }
   
   // Usage.
   uint a = (uint)MyEnum.ValueA;
   uint b = (uint)MyEnum.ValueB;
   uint c = unchecked((uint)MyEnum.ValueC);
   uint d = (uint)document["MyProperty"].AsInt32; // Reading from a BsonDocument.
   

3. Serialize manually(UInt32Serializer, UInt64Serializer, etc).