CODEWITHSUNDEEP
entity-frameworkangularjsbreeze
newman
newman

Reputation: 6911

Angular/Breeze: How to define a zero-to-many relationship in Entity Framework code first?

I'm working on an angular/breeze web app with EF code first, and run into a strange problem. Here is the code snippet:

public class Person
{
    public int Id { get; set; }
    public int? AddressId { get; set; }
    public virtual Address Address { get; set; }
}
public class Address
{
    public int Id { get; set; }     
    public virtual ICollection<Person> Persons { get; set; }
}

// DbContext
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Person>().HasOptional(x => x.Address).WithMany(x => x.Persons).WillCascadeOnDelete(false);      
    base.OnModelCreating(modelBuilder);
}

Everything runs fine except one case: You can create a Person without specifying an address, however, once you select an address for the person, you can change to another one, but you can't remove it.

This is how I remove it in Angular select:

<option value=""></option>

This is the error I got when trying to reset the address:

{"The UPDATE statement conflicted with the FOREIGN KEY constraint \"FK_dbo.Person_dbo.Address_AddressId\". The conflict occurred in database \"MyDb\", table \"dbo.Address\", column 'Id'.\r\nThe statement has been terminated."}

So, what's wrong?

UPDATE: As I figured out, the problem seems to be on the client side. When an empty option is selected, it sets the AddressId to 0, instead of NULL. If I change it to NULL in debug mode, it would work. This is the complete select code:

<select ng-model="person.address" ng-options="g.name for g in addressList"><option value=""></option></select>

Now, the question is that how can I make it return its id as NULL instead of 0 in case an empty address is selected?

Upvotes: 0

Views: 316

Answers (1)

Ward
Ward

Reputation: 17863

Can you set up a plunker?

It seems to me that the Person.addressId should be flagged as nullable in the metadata (can you confirm?) and therefore Breeze should set addressId to null (not 0) when you null the Person.address.

I have a feeling this may be an Angular issue involving your combobox binding option, <option value=""></option>. I'm not sure that is doing what you think it is doing when used in combination with ng-options="g.name for g in addressList".

You might consider placing a "button" ('x' for "clear") next to the combobox that, when clicked, sets Person.address = null or Person.addressId = null.

Upvotes: 1

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