OPC Studio User's Guide and Reference
TryGetFieldValue(UAAttributeField,Object) Method



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > UAEventData Class > TryGetFieldValue Method : TryGetFieldValue(UAAttributeField,Object) Method
Attribute field to look up in the event data.

Because the UAAttributeField has an implicit conversion from OpcLabs.EasyOpc.UA.Filtering.UASimpleAttributeOperand, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Filtering.UASimpleAttributeOperand in place of this parameter, and the corresponding OPC UA attribute field will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromUASimpleAttributeOperand static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

The value found, or a null reference if the attribute field has not been found.

The value of this parameter can be null (Nothing in Visual Basic).

Attempts to retrieve a value of specified field from the event data.
Syntax
'Declaration
 
Public Overloads Function TryGetFieldValue( _
   ByVal attributeField As UAAttributeField, _
   ByRef value As Object _
) As Boolean
'Usage
 
Dim instance As UAEventData
Dim attributeField As UAAttributeField
Dim value As Object
Dim value As Boolean
 
value = instance.TryGetFieldValue(attributeField, value)
public bool TryGetFieldValue( 
   UAAttributeField attributeField,
   out object value
)
public:
bool TryGetFieldValue( 
   UAAttributeField^ attributeField,
   [Out] Object^ value
) 

Parameters

attributeField
Attribute field to look up in the event data.

Because the UAAttributeField has an implicit conversion from OpcLabs.EasyOpc.UA.Filtering.UASimpleAttributeOperand, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Filtering.UASimpleAttributeOperand in place of this parameter, and the corresponding OPC UA attribute field will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromUASimpleAttributeOperand static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

value
The value found, or a null reference if the attribute field has not been found.

The value of this parameter can be null (Nothing in Visual Basic).

Return Value

Returns true if the attribute field has been found; false otherwise.
Exceptions
ExceptionDescription

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.

Requirements

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

See Also