What is a CoreData error?

Question

Can someone explain what coredata protection means? I realized that this is a memory reduction mechanism. But my question is: if when trying to use a damaged object we need to call some update methods, or will CoreData choose the values ​​for us? If CoreData processes it for us, what happens if the deleted object is deleted from the real persistent storage and we try to access it through the damaged object? Will this be an exception?

Answer 1

In the master data, errors are placeholders or "unrealized objects." These are small objects that relate to other NSManagedObjects, which are retrieved only as needed. This failure mechanism is designed to improve performance and reduce memory usage.

In general, the failure mechanism is transparent; when you retrieve an object from an NSManagedObjectContext (MOC), you cannot tell (during its normal operation) whether its an error or an implemented object. In most cases, the error will be automatically converted to the implemented object ("fired") by the Core Data database when it is necessary to do this, for example, when accessing the object of the object. If you need to run the error yourself, you can do this by calling the willAccessValueForKey: method with the nil argument.

Answer 2

Great answer from Dhruva! In response to your last question, if you try to access a managed entity that was first knocked down and then deleted, you will see an NSObjectInaccessibleException exception and the message “Master data cannot execute the error”

Answer 3

from the Coredata link:

Failure reduces the amount of memory consumed by your application. An error is a placeholder that represents a managed entity that is not yet fully implemented, or a collection entity that represents a relationship.