Cannotdeserializeobjectidfrombsontypedocument UPDATED
CLICK HERE - https://tiurll.com/2tvESF
How to fix FormatException: Cannot deserialize a 'Guid' from BsonType 'ObjectId'
If you are working with MongoDB and C#, you may encounter this error when trying to deserialize a document that has a Guid field mapped to an ObjectId in the database. This can happen if you use the default Guid serializer, which expects a binary representation of the Guid, but the database stores it as an ObjectId, which is a 12-byte value.
One way to fix this error is to use a custom Guid serializer that can handle both binary and string representations of the Guid. You can register this serializer globally or for a specific class or property. Here is an example of how to do it:
using MongoDB.Bson;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Serializers;
using System;
namespace StackOverflow
{
// A custom Guid serializer that can handle both binary and string representations
public class CustomGuidSerializer : SerializerBase
{
public override Guid Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
{
var bsonType = context.Reader.GetCurrentBsonType();
switch (bsonType)
{
case BsonType.Binary:
// Use the default Guid serializer for binary values
return new GuidSerializer(GuidRepresentation.Standard).Deserialize(context, args);
case BsonType.String:
// Parse the string value as an ObjectId and convert it to a Guid
var objectId = ObjectId.Parse(context.Reader.ReadString());
return new Guid(objectId.ToByteArray());
default:
throw new FormatException($\"Cannot deserialize a 'Guid' from BsonType '{bsonType}'.\");
}
}
public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, Guid value)
{
// Use the default Guid serializer for serialization
new GuidSerializer(GuidRepresentation.Standard).Serialize(context, args, value);
}
}
// A sample class that has a Guid property
public class Sample
{
public Guid Id { get; set; }
}
class Program
{
static void Main(string[] args)
{
// Register the custom Guid serializer globally
BsonSerializer.RegisterSerializer(new CustomGuidSerializer());
// Or register it for a specific class or property
//BsonClassMap.RegisterClassMap(cm =>
//{
// cm.AutoMap();
// cm.MapIdMember(c => c.Id).SetSerializer(new CustomGuidSerializer());
//});
// Test deserialization
var document = new BsonDocument
{
{ \"_id\", ObjectId.GenerateNewId() }
};
var sample = BsonSerializer.Deserialize(document);
Console.WriteLine(sample.Id); // Prints a valid Guid
}
}
}
This solution is based on the answer by dododo on Stack Overflow[^1^]. You can also check out other answers on the same question for more details and alternatives. aa16f39245