ReadValueNonNull<TValue>(IEasyUAClient,UANodeArguments,UAAttributeId) Method

Reads a value of a specified attribute, converts it to the specified type, ensures it is not null, and throws an exception if the operation fails.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<JetBrains.Annotations.NotNullAttribute()>
Public Overloads Shared Function ReadValueNonNull(Of TValue)( _
   ByVal client As IEasyUAClient, _
   ByVal nodeArguments As UANodeArguments, _
   ByVal attributeId As UAAttributeId _
) As TValue

'Usage
 
Dim client As IEasyUAClient
Dim nodeArguments As UANodeArguments
Dim attributeId As UAAttributeId
Dim value As TValue
 
value = IEasyUAClientExtension2.ReadValueNonNull(Of TValue)(client, nodeArguments, attributeId)

[Extension()]
[JetBrains.Annotations.NotNull()]
public static TValue ReadValueNonNull<TValue>( 
   IEasyUAClient client,
   UANodeArguments nodeArguments,
   UAAttributeId attributeId
)

[Extension()]
[JetBrains.Annotations.NotNull()]
public:
static TValue^ ReadValueNonNullgeneric<typename TValue>
( 
   IEasyUAClient^ client,
   UANodeArguments^ nodeArguments,
   UAAttributeId attributeId
)

Parameters

client: The client object that will perform the operation.
The value of this parameter cannot be null (Nothing in Visual Basic).
nodeArguments: An arguments object that specifies the node in the OPC server.
The value of this parameter cannot be null (Nothing in Visual Basic).
attributeId: The Id of the attribute to read.

Type Parameters

TValue: The type to convert the attribute value to.

Return Value

A non-null attribute value converted to type .

This method never returns null (Nothing in Visual Basic).

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.
System.ComponentModel.InvalidEnumArgumentException	An invalid enumeration value was used. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.
OpcLabs.EasyOpc.UA.OperationModel.UAException	The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause. This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

System.ArgumentNullException

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

System.ComponentModel.InvalidEnumArgumentException

An invalid enumeration value was used.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

OpcLabs.EasyOpc.UA.OperationModel.UAException

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Remarks

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

IEasyUAClientExtension2 Class
IEasyUAClientExtension2 Members
Overload List

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