# NullableCodec<T>.WriteField(Writer<TBufferWriter>, uint, Type, T?)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.serialization/orleans.serialization.codecs.nullablecodec-1/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.serialization/orleans.serialization.codecs.nullablecodec-1/methods/)

[Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Serialization/Codecs/NullableCodec.cs#L36-L44)

```csharp
public void WriteField<TBufferWriter>(ref Writer<TBufferWriter> writer, uint fieldIdDelta, Type expectedType, T? value)
```

Writes a field.

### Parameters

- `writer` (`Writer<TBufferWriter>`): The writer.
- `fieldIdDelta` (`uint`): The field identifier delta.
- `expectedType` (`Type`): The expected type.
- `value` (`T?`): The value.