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Removing all records from navigation properties in Entity Framework

I have 1:N relationship between Program and Student tables which EF converted into navigation property. Now I want to delete all those records in this navigation students. I started like this:

foreach(Student student in program.Students)
program.Students.Remove(student);

But I am a little bit skeptical about this.

Than I tried this way:

while (program.Students.Count > 0)
    program.Students.Remove(program.Students.ToList()[0]);

But this seems weird too.

Is there some simpler way to do this or if not which way is the best?

like image 403
Vajda Avatar asked May 30 '11 21:05

Vajda


3 Answers

Unless you have very special association called identifying relation between your program and students you should use something like this:

foreach(var student in program.Students.ToList())
{
    program.Students.Remove(student); // Break realation
    context.Students.DeleteObject(student); // Delete student
}

Removing student from the navigation property will only set FK in the student to null but the record will not be deleted. If FK is not nullable you will get an exception.

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Ladislav Mrnka Avatar answered Nov 05 '22 12:11

Ladislav Mrnka


I really don't know if it's gonna work or not, but I can not help it, I'm curious. Is program.Students.Clear() working? Or maybe reset it, reinitializing it? I hope it helped you...

Edit: Please use @Ladislav Mrnka's response, as that is the correct one. I have tried to remove the answer but I cannot because it's the accepted one

like image 31
Adrian Ancuta Avatar answered Nov 05 '22 12:11

Adrian Ancuta


.Clear() method is very good. It deletes all navigation properties in database. That's simple rather than foreach loop.

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Nguyễn Trọng Bằng Avatar answered Nov 05 '22 12:11

Nguyễn Trọng Bằng