How to delete an object by id with entity framework

Question

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   gt  c Id    1    context DeleteObject customer    context Savechanges      So I need to hit database twice  Is there a easier way

User · Answer

A smaller version  when compared to previous ones    var customer   context Find id   context Delete customer   context SaveChanges

User · Answer

Raw sql query is fastest way I suppose  public void DeleteCustomer int id       using  var context   new Context               const string query    DELETE FROM  dbo   Customers  WHERE  id   0          var rows   context Database ExecuteSqlCommand query id            rows  gt   1 - count of deleted rows           rows   0 - nothing to delete

User · Answer

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

User · Answer

If you dont want to query for it just create an entity  and then delete it   Customer customer    new Customer      Id   1        context AttachTo  Customers   customer   context DeleteObject customer   context Savechanges

User · Answer

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

User · Answer

This answer is actually taken from Scott Allen s course titled ASP NET MVC 5 Fundamentals  I thought I d share because I think it is slightly simpler and more intuitive than any of the answers here already  Also note according to Scott Allen and other trainings I ve done  find method is an optimized way to retrieve a resource from database that can use caching if it already has been retrieved  In this code  collection refers to a DBSet of objects  Object can be any generic object type            var object   context collection Find id             context collection Remove object           context SaveChanges

User · Answer

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   gt  x LastLoginDate  lt  DateTime Now AddYears -2         Delete      It is also useful for bulk deletes

User · Answer

I am using the following code in one of my projects       using  var  context   new DBContext new DbContextOptions lt DBContext gt                    try                        context MyItems Remove new MyItem     MyItemId   id                 await  context SaveChangesAsync                      catch  Exception ex                        if    context MyItems Any i   gt  i MyItemId    id                                 return NotFound                              else                               throw ex                                  This way  it will query the database twice only if an exception occurs when trying to remove the item with the specified ID  Then if the item is not found  it returns a meaningful message  otherwise  it just throws the exception back  you can handle this in a way more fit to your case using different catch blocks for different exception types  add more custom checks using if blocks etc      I am using this code in a MVC  Net Core  Net Core project with Entity Framework Core

User · Answer

dwkd s answer mostly worked for me in Entity Framework core  except when I saw this exception      InvalidOperationException  The instance of entity type  Customer  cannot   be tracked because another instance with the same key value for   Id     is already being tracked  When attaching existing entities  ensure   that only one entity instance with a given key value is attached    Consider using  DbContextOptionsBuilder EnableSensitiveDataLogging  to   see the conflicting key values    To avoid the exception  I updated the code   Customer customer   context Customers Local First c   gt  c Id    id   if  customer    null        customer   new Customer      Id   id        context Customers Attach customer     context Customers Remove customer   context SaveChanges

[entity-framework] How to delete an object by id with entity framework

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