Question

I’m writing test code that needs to clean up the entities it creates when done. To account for the possibility that the test ended prematurely, I run the cleanup code when the test is initialized as well.

I’m using this recommendation

https://stackoverflow.com/a/5522422/141172

var category = new Category() { CategoryId = 1 };
context.Categories.Attach(category);
context.Categories.Remove(category);
context.SaveChanges();

to delete the entities. However, if the entities were already deleted (e.g. previous test run successfully cleaned up),

ctx.SaveChanges();

throws an Exception:

Store update, insert, or delete statement affected an unexpected
number of rows (0)

That makes perfect sense, but just catching the Exception is a bit awkward. Is there a cleaner way to accomplish this without introducing an extra trip to the DB to check for the entity?

Answer 1

The easiest and cleanest way to do this is not to use a fake entity, but to run a simple SQL query:

var rows = context.Database.ExecuteSqlCommand("delete Category where ...");
if (rows == 0)
    //nothing was deleted