删除一对多关系中的相关实体

Question

I have this domain:

public class Phone {
    public int Id { get; set; }
    public string Number { get; set; }
    public Person Person { get; set; }
}
public class Person {
    public int Id { get; set; }
    public IList<Phone> Phones { get; set; }
}

I load a Person and clear its Phones . But the operation cause an error:

// actually loads person from repository...
var person = _personRepository.Include(p => p.Phones).Where(p => p.Id == 1).First();
person.Phones.Clear();
_personRepository.Update(person);

Above you can see the simpled logic of loading a Person and clearing its Phones . But this error occurs:

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.

Actually I want to clear all of Person.Phones and add some new items. But I want to clearing them in one query, not delete them one by one.

Have you any idea? Can you help me please? Thanks in advance.

Answer 1

You can't generate set based SQL in EF. So there's no way in EF to generate a single SQL statement that deletes all Phone records given a Person.Id .

You can write the SQL yourself and pass it to either ObjectContext.ExecuteStoreCommand or DbContext.Database.ExecuteSqlCommand depending on your model.

Answer 2

foreach(var phone in person.Phones)
{
   context.DeleteObject(phone);
}
person.Phones.Clear();

may help.