Lightstreamer PCL (Portable Class Library) Client 3.1.0
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IUpdateInfo.GetOldValue Method (string)

Gets the value for a field as it was before the reception of this update. If the current update is the first one, then all old values are null. 

If the "COMMAND logic" behaviour is enabled, then the value is meant as relative to the same key; as a consequence, on ADD commands all old values are null. 

 

C++
string GetOldValue(string fieldName);
C#
string GetOldValue(string fieldName);
Visual Basic
Function GetOldValue(fieldName As string) As string
Parameters 
Description 
string fieldName 
a field name. 

the previous field value, according to the above specifications; null is a legal value too.

Exceptions 
Description 
ArgumentException 
the specified field name does not represent a subscribed field; also thrown if a SimpleTableInfo was used to describe the related table.