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.