Programming Entity Framework

Chapter 18. Handling Entity Framework Exceptions

Things can go awry in many ways when you’re querying or updating entities. The Entity Data Model (EDM), for example, could have a problem that the validator fails to detect but that makes it difficult for a query to be compiled. You might attempt to save entities to the database that are missing related data—a reservation without a trip, perhaps, or a reservation without a customer. The database might have a constraint that is not reflected in the model; if a user saves data that breaks the rule of the constraint, the database will throw an error. Or someone may have modified or even deleted a record while another user was editing it.

The Entity Framework includes a specialized set of exceptions for capturing problems like these that arise during query and command execution.

In your application, you should embed each query execution or call you make to SaveChanges in some sort of mechanism for catching these exceptions, most likely a Try/Catch block. When one of these exceptions is raised, it is up to your code to handle it.

In this chapter, we’ll look at exception handling that is unique to the Entity Framework. Some exceptions are Entity Framework-specific exceptions, and others are .NET exceptions caused by faulty operations in the Entity Framework. You’ll also spend a good deal of time focusing on concurrency exceptions, which are raised by a database conflict is caused when multiple users edit the same data concurrently.

Note

You ...