How to delete an object by id with entity framework

How to delete an object by id with entity framework

It seems to me that I have to retrieve an object before I delete it with entity framework like below

var customer = context.Customers.First(c => c.Id == 1);

context.DeleteObject(customer);

context.Savechanges();

So I need to hit database twice. Is there a easier way?

回答1

In Entity Framework 6 the delete action is Remove. Here is an example

Customer customer = new Customer () { Id = id };
context.Customers.Attach(customer);
context.Customers.Remove(customer);
context.SaveChanges();

评论

Why Attach? Why not just Remove and SaveChanges?

– runeks

Sep 25, 2018 at 12:45

 

You have to attach your entity in the context because if you don't do that, you will receive an error while removing. EF can remove entities in this context only

– Pierre-Luc

Jan 9, 2019 at 14:43

 

@runeks according to the manual the entity must exist in the context before the Remove operation can be performed. See here docs.microsoft.com/en-us/dotnet/api/…

– dwkd

Jan 28, 2019 at 23:51

回答2

The same as @Nix with a small change to be strongly typed:

If you don't want to query for it just create an entity, and then delete it.

Customer customer = new Customer () { Id = id };
context.Customers.Attach(customer);
context.Customers.DeleteObject(customer);
context.SaveChanges();

回答3

Similar question here.

With Entity Framework there is EntityFramework-Plus (extensions library).
Available on NuGet. Then you can write something like:

// DELETE all users which has been inactive for 2 years
ctx.Users.Where(x => x.LastLoginDate < DateTime.Now.AddYears(-2))
     .Delete();

It is also useful for bulk deletes.