How do you serialize value types with MongoDB C # serializer?
2 answers
You can create your own serializer to handle structs with this code:
public class StructBsonSerializer : IBsonSerializer
{
public void Serialize(BsonWriter bsonWriter, Type nominalType, object value, IBsonSerializationOptions options)
{
var fields = nominalType.GetFields(BindingFlags.Instance | BindingFlags.Public);
var propsAll = nominalType.GetProperties(BindingFlags.Instance | BindingFlags.Public);
var props = new List<PropertyInfo>();
foreach (var prop in propsAll)
{
if (prop.CanWrite)
{
props.Add(prop);
}
}
bsonWriter.WriteStartDocument();
foreach (var field in fields)
{
bsonWriter.WriteName(field.Name);
BsonSerializer.Serialize(bsonWriter, field.FieldType, field.GetValue(value));
}
foreach (var prop in props)
{
bsonWriter.WriteName(prop.Name);
BsonSerializer.Serialize(bsonWriter, prop.PropertyType, prop.GetValue(value, null));
}
bsonWriter.WriteEndDocument();
}
public object Deserialize(BsonReader bsonReader, Type nominalType, Type actualType, IBsonSerializationOptions options)
{
var obj = Activator.CreateInstance(actualType);
bsonReader.ReadStartDocument();
while (bsonReader.ReadBsonType() != BsonType.EndOfDocument)
{
var name = bsonReader.ReadName();
var field = actualType.GetField(name);
if (field != null)
{
var value = BsonSerializer.Deserialize(bsonReader, field.FieldType);
field.SetValue(obj, value);
}
var prop = actualType.GetProperty(name);
if (prop != null)
{
var value = BsonSerializer.Deserialize(bsonReader, prop.PropertyType);
prop.SetValue(obj, value, null);
}
}
bsonReader.ReadEndDocument();
return obj;
}
public object Deserialize(BsonReader bsonReader, Type nominalType, IBsonSerializationOptions options)
{
return Deserialize(bsonReader, nominalType, nominalType, options);
}
public bool GetDocumentId(object document, out object id, out Type idNominalType, out IIdGenerator idGenerator)
{
throw new NotImplementedException();
}
public void SetDocumentId(object document, object id)
{
throw new NotImplementedException();
}
}
Then, register this serializer for your struct:
BsonSerializer.RegisterSerializer(typeof(MyStruct), new StructBsonSerializer());
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Based on the above code, I manage to adapt it to version 2.2.3 of Mongo Driver.
public class BasicStructSerializer<T> : StructSerializerBase<T> where T: struct
{
public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, T value)
{
var nominalType = args.NominalType;
var fields = nominalType.GetFields(BindingFlags.Instance | BindingFlags.Public);
var propsAll = nominalType.GetProperties(BindingFlags.Instance | BindingFlags.Public);
var props = new List<PropertyInfo>();
foreach (var prop in propsAll)
{
if (prop.CanWrite)
{
props.Add(prop);
}
}
var bsonWriter = context.Writer;
bsonWriter.WriteStartDocument();
foreach (var field in fields)
{
bsonWriter.WriteName(field.Name);
BsonSerializer.Serialize(bsonWriter, field.FieldType, field.GetValue(value));
}
foreach (var prop in props)
{
bsonWriter.WriteName(prop.Name);
BsonSerializer.Serialize(bsonWriter, prop.PropertyType, prop.GetValue(value, null));
}
bsonWriter.WriteEndDocument();
}
public override T Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
{
//boxing is required for SetValue to work
var obj = (object)(new T());
var actualType = args.NominalType;
var bsonReader = context.Reader;
bsonReader.ReadStartDocument();
while (bsonReader.ReadBsonType() != BsonType.EndOfDocument)
{
var name = bsonReader.ReadName();
var field = actualType.GetField(name);
if (field != null)
{
var value = BsonSerializer.Deserialize(bsonReader, field.FieldType);
field.SetValue(obj, value);
}
var prop = actualType.GetProperty(name);
if (prop != null)
{
var value = BsonSerializer.Deserialize(bsonReader, prop.PropertyType);
prop.SetValue(obj, value, null);
}
}
bsonReader.ReadEndDocument();
return (T)obj;
}
}
Using:
cm.GetMemberMap(c => c.SomeMemberName).SetSerializer(new BasicStructSerializer<SomeMemberType>());
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