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Handling Errors

Errors in serialization are handled with exceptions. Typically, the serialize() functions do not catch serialization exceptions but let them flow to the caller. Most exceptions are thrown by the archives, but it is possible to generate custom errors in serialization functions. The type used for serialization errors is PiiSerializationException.

Custom serialization errors are most conveniently handled with the PII_SERIALIZATION_CUSTOM_ERROR macro declared in PiiSerializationException.h. 

 template <class Archive> void MyClass::serialize(Archive& ar, const unsigned int)
   {
     PII_SERIALIZATION_CUSTOM_ERROR("MyClass is not serializable!");
   }

Errors must be handled in the application that invokes serialization code by catching PiiSerializationException. The error code tells the reason of failure. If you want textual output, use the message() function. PiiSerializationException also has a info() function that returns extra information for debugging purposes. It is filled with a class name when no serializer or no factory is found for an object. 

 MyClass obj;
 QFile textFile(fileName);
 textFile.open(QIODevice::WriteOnly);
 PiiTextOutputArchive ar(&textFile);

 try
   {
     PII_SERIALIZE(ar, obj);
   }
 catch (PiiSerializationException& ex)
   {
     qDebug("Error code: %d
Message: %s",
            ex.code(), qPrintable(ex.message()));
   }

Note that the archive may not always be able to find out the real reason of an error. If stored data is corrupted, it may in principle result in any type of an error. InvalidDataFormat is only thrown when the archive notices it is reading something it isn't expecting.

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