# OpcDataField Class

> Reference: Represents a data field declared by the structured data type of a specific OpcDataObject instance.

<span class="api-meta">since v2.8</span>

<dl class="api-definition">
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx">Opc.UaFx</a></dd>
<dt>Assembly</dt>
<dd>Opc.UaFx.Advanced.dll</dd>
<dt>Package</dt>
<dd>Opc.UaFx.Advanced v2.59.0</dd>
<dt>Members</dt>
<dd><a href="./members">OpcDataField Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Represents a data field declared by the structured data type of a specific [OpcDataObject](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdataobject/) instance.

## Syntax

<div class="api-signature" data-lang="csharp">

```csharp
public sealed class OpcDataField
```

</div>

<div class="api-signature" data-lang="vbnet">

```vbnet
Public NotInheritable Class OpcDataField
```

</div>

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → **OpcDataField**

## Properties

| Name | Description |
|---|---|
| [Exists](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#exists) | Gets a value indicating whether the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) of the field is part of the data object this field belongs to. |
| [HasValue](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#hasvalue) | Gets a value indicating whether the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) property has been set. |
| [IsOptional](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#isoptional) | Gets a value indicating whether the current field might not necessarily exist in the data object this field belongs to. |
| [Length](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#length) | Gets the length of the field expressed either explicit or implicit using a different OpcDataField. |
| [LengthField](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#lengthfield) | Gets the field which explictly controls the [Length](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#length) of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) of this field. |
| [Name](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#name) | Gets the name of the current OpcDataField. |
| [SwitchField](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#switchfield) | Gets the field which explictly controls the existence of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) of this field in the data object this field belongs to. |
| [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) | Gets or sets the value associated with the current field. |
| [ValueType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#valuetype) | Gets the [Type](https://learn.microsoft.com/dotnet/api/system.type) of [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) the current field supports. |

## Methods

| Name | Description |
|---|---|
| [ToString](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#tostring)<span class="api-meta">override</span> | Returns a [string](https://learn.microsoft.com/dotnet/api/system.string) representing the [Name](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#name), [ValueType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#valuetype) and [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatafield/members#value) of the current OpcDataField. |

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.8–v2.59 |