I have problem with deleting related rows in Entity Framework 4.1. I have tables with relations
Book 1<--->* BookFormats
I have set the on delete cascade:
ALTER TABLE [dbo].[BookFormats] WITH CHECK ADD CONSTRAINT [FK_BookFormats_Book]
FOREIGN KEY([BookID]) REFERENCES [dbo].[Book] ([BookID]) on delete cascade
The EDMX property
Then, I want to remove the all BokFormats
items related to my Book
object:
var originalBook = m.db.Book.First(x => x.BookID == bookId);
originalBook.BookFormats.Clear();
m.db.SaveChanges();
But, I get the error:
The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted.
I ran out of ideas on how to delete these objects. Any ideas?
Cascading deletes are needed when a dependent/child entity can no longer be associated with its current principal/parent. This can happen because the principal/parent is deleted, or it can happen when the principal/parent still exists but the dependent/child is no longer associated with it.
ON DELETE CASCADE is fine, but only when the dependent rows are really a logical extension of the row being deleted. For example, it's OK for DELETE ORDERS to delete the associated ORDER_LINES because clearly you want to delete this order, which consists of a header and some lines.
after manual set the property,single call to "dbContext. As. Remove(someA)" work as expected!
Use the ON DELETE CASCADE option to specify whether you want rows deleted in a child table when corresponding rows are deleted in the parent table. If you do not specify cascading deletes, the default behavior of the database server prevents you from deleting data in a table if other tables reference it.
You can use RemoveRange :
m.db.BookFormats.RemoveRange(originalBook.BookFormats);
m.db.SaveChanges();
But this is for EF 6.0
Cascade deletions concept is as follows:
When you delete Book
from the DB all related BookFormats
will be deleted for you by SQL Server (please note that it doesn't matter how deletion of Book
will be initiated via EF or raw SQL). Thus it has nothing to do with your task: "I want to delete all BookFormats
related to my Book
". To accomplish it you need something like this:
foreach(var m in m.db.BookFormats.Where(f=>f.BookID == bookID))
{
m.db.BookFormats.Remove(m);
}
m.db.SaveChanges();
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With