# Codec_Observation.WriteField(Writer<TBufferWriter>, uint, Type, Observation)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.transactions.testkit.base/orleanscodegen.orleans.transactions.testkit.consistency.codec-observation/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.transactions.testkit.base/orleanscodegen.orleans.transactions.testkit.consistency.codec-observation/methods/)

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

Writes a field.

### Parameters

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