How to delete a list of object using ObjectContext?

Question

Say you have code like this .

using (CustomerContext db = new CustomerContext())
{
   var foundCustList=db.Customers.Where(c=>c.State=='-1').ToList();//Find all the customer which State is -1
   foreach(var c in foundCustList)
   {
       db.DeleteObject(c);
   }
   db.SaveChanges();//After all the customer is deleted, Commit.
}

But I want to know Is there any way to delete the list of object easily? I don't want to use the foreach to do it one by one for a list . thanks.

Sergey Berezovskiy · Accepted Answer · 2012-12-14T07:22:11.903

16

You can use EntityFramework.Extended library, which is available from Nuget (don't forget to add using EntityFramework.Extensions;):

db.Customers.Delete(c => c.State == '-1');

Or you can write extension method manually:

public static void DeleteObjects<T>(this ObjectSet<T> set, 
                                    IEnumerable<T> entities)
    where T : EntityObject
{
    foreach (var entity in entities)
        set.DeleteObject(entity);
}

Usage:

var customersToDelete = db.Customers.Where(c => c.State == '-1');
db.Customers.DeleteObjects(customersToDelete);

Or better one:

public static void DeleteObjects<T>(this ObjectSet<T> set, 
                                    Expression<Func<T, bool>> predicate)
    where T : EntityObject
{
    foreach (var entity in set.AsQueryable<T>().Where(predicate))
        set.DeleteObject(entity);
}

Usage:

db.Customers.DeleteObjects(c => c.State == '-1');

edited Dec 14 '12 at 07:22

answered Dec 14 '12 at 06:52

Sergey Berezovskiy

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What do you think of Sidharth Mudgal's answer ? – Joe.wang Dec 14 '12 at 06:54
1

@Joe.wang `db.Customers` if of type `ObjectSet` or `Db` - it's not List – Sergey Berezovskiy Dec 14 '12 at 06:59
Good point. I think so. I am afraid that EF doesn't know what happen to the `Customers` changes. – Joe.wang Dec 14 '12 at 07:03
1

@Joe.wang when you call DeleteObject EF just changes its state. Real deletion from db will occur when you'll call SaveChanges on context. – Sergey Berezovskiy Dec 14 '12 at 07:10
1

For any googlers, EntityFramework.Extended has been updated; the new syntax is `db.Customers.Where(c => c.State == '-1').Delete();`. – levininja May 06 '15 at 18:55

iGanja · Answer 2 · 2016-07-07T16:08:17.027

10

The accepted answer above is outdated as the syntax has been deprecated in favor of deleting a simple query instead:

db.Customers.Where(c => c.State == '-1').Delete();

edited Jul 07 '16 at 16:08

answered Jul 01 '16 at 01:15

iGanja

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1

Have you considered adding a comment to the other answerer (who was last online 11 hours ago, so is probably active on the site), so that they can update their own post? It would've taken less effort than writing up this little rant of yours (which is a shame, since the information buried inside is indeed useful). – Andras Deak -- Слава Україні Jul 01 '16 at 01:37
@AndrasDeak Nope. This is a community forum, not a blog. However, if a couple over-zealous, idealistic, community members wish to protect the integrity of the thread history, rather than the accuracy and accessibility of the of the content, who am I to argue. I like my "rant". If it changes one self-imposed moderators view of things, it served its purpose. – iGanja Jul 05 '16 at 17:46
1

@iGanja Stack Overflow is not a forum, it's a collection of useful answers to useful questions. cf http://meta.stackexchange.com/a/92110/186209 – pb2q Jul 07 '16 at 12:19
@pb2q It is NOT a blog, which was my point. But thank you for yet another off-topic semantically argument. You did however stumble across my original point; the "usefulness" of this thread is enhanced by editing the outdated answer, NOT adding a more current, accurate yet highly obscured answer that users must hunt for. It really is a shame the elitists - more interested in protocol than truth - don't get that. – iGanja Jul 07 '16 at 16:04
1

@iGanja I regret that you find my comment off-topic and that you may see this as elitism. I see that I had missed your point and it does have some merit: old accepted answers can get stale. Note that with enough rep you can edit the answers of others, but my interpretation of the "philosophy" of the site is that you should instead try to add a better answer of your own, even after considering the flaw that you're suggesting. If you're interested I would recommend that you get involved with the meta-discussion site meta.stackoverflow.com: this kind of discussion is definitely on topic there. – pb2q Jul 07 '16 at 16:57

Sidharth Mudgal · Answer 3 · 2012-12-14T07:22:08.410

6

db.Customers.Where(c => c.State == '-1').ToList().ForEach(db.DeleteObject);
db.SaveChanges();

should be all you need.

edited Dec 14 '12 at 07:22

answered Dec 14 '12 at 06:34

Sidharth Mudgal

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Its not part of EF. Its part of `List`. Use `System.Collections.Generic` – Sidharth Mudgal Dec 14 '12 at 06:45
I was using Model View to generate all the entities class code. these are generate by EF . Are you sure `RemoveAll` is used to delete DB records by EF? – Joe.wang Dec 14 '12 at 06:51
1

@Jow.wang, I mistook RemoveAll to be part of `IEnumerable`. Anyways made edits. But I think the one-liner with `EntityFramework.Extensions` might be better as lazyberezovsky said. – Sidharth Mudgal Dec 14 '12 at 07:25

score 3 · Answer 4 · answered Jan 07 '20 at 07:59

Entity Framework Core

3.1 3.0 2.2 2.1 2.0 1.1 1.0

using (CustomerContext db = new CustomerContext())
{
    var foundCustList=db.Customers.Where(c=>c.State=='-1').ToList();//Find all the customer which State is -1
    db.Customers.RemoveRange(foundCustList);
    db.SaveChanges();//After all the customer is deleted, Commit.
}

Summary:

Removes the given collection of entities from the context underlying the set with each entity being put into the Deleted state such that it will be deleted from the database when SaveChanges is called.

Remarks:

Note that if System.Data.Entity.Infrastructure.DbContextConfiguration.AutoDetectChangesEnabled is set to true (which is the default), then DetectChanges will be called once before delete any entities and will not be called again. This means that in some situations RemoveRange may perform significantly better than calling Remove multiple times would do. Note that if any entity exists in the context in the Added state, then this method will cause it to be detached from the context. This is because an Added entity is assumed not to exist in the database such that trying to delete it does not make sense.

How to delete a list of object using ObjectContext?

4 Answers4