Delete object and all its child objects in Entity Framework?

Question

I've been trying to find the answer to this question here. Several people seem to ask similar things, but I don't get the answers. I have an EF entity with a bunch of child entities (one-to-many relationship). I want to be able to delete the "parent" entity and have all the child entities deleted at the same time.

Some people mention "Cascade Delete" should be set on both EF model and database (Sql Server in my case). The problem is:

1. I have absolutely no idea how to do this (seems to be implied in those answers that you should know, but sorry...)
2. I have a feeling I've run into a similar problems before and found an answer somewhere that was simpler than setting this Cascade Delete. I may be wrong, maybe it is the only way, but if there is a simpler solution I'd like to know.

In either case, a clear example of how to get this working would be greatly appreciated!

Answer 1

In SQL Managment Studio go to your database and find the table where there should be a foreign key. Add a foreign key to the table pointing to the other table. I assume you know how to setup a foreign key. In the foreign key setup at the bottom of the dialog window you'll see a Delete property. Set it to Cascade. This will cause any dependent rows to be deleted whenever the parent row is deleted. Then go and update your data model in Visual Studio. Everything should be setup for you now.

Answer 2

Here is some relevant documentation on MSDN. Note though that there appears to be an error in the example. I received the following error from the EDMX designer when using this configuration.

Operations cannot be specified on ends with multiplicity '*'.

You should set the OnDelete property to Cascade for the end will be triggering deletes on the other end.

As an example, in a relationship involving customers and orders where you would like to have a customer's orders deleted along with the customer, you should set the OnDelete property for the Customer role to Cascade.

Note that only objects that have been loaded into the ObjectContext will be affected by a cascading delete. You will be relying on the cascading delete that you set in the database to look after any other records.