Entity Framework Core nullable foreign key

Question

I am having trouble getting a list of entities where a foreign key value could be null.

The Models:

public class Company
{
    [Key]
    [Required]
    public int Id { get; set; }
    [Display(Name = "Company Name")]
    public string CompanyName { get; set; }
    [Display(Name = "Main Phone")]
    public string LandPhone { get; set; }
    [Display(Name = "Fax")]
    public string FaxPhone { get; set; }
}

public class Contact
{
    [Key]
    [Required]
    public int Id { get; set; }
    [Display(Name ="First Name")]
    public string FirstName { get; set; }
    [Display(Name = "Last Name")]
    public string LastName { get; set; }
    [EmailAddress]
    public string Email { get; set; }
    [Display(Name = "Mobile Phone")]
    public string MobilePhone { get; set; }
    [Display(Name = "Office Phone")]
    public string LandPhone { get; set; }
    [Display(Name = "Fax")]
    public string FaxPhone { get; set; }
    public string Title { get; set; }
    public int CompanyId { get; set; }
    [ForeignKey("CompanyId")]
    public Company Company { get; set; }
}

When I try and get the list of all Contacts and one of them has a null value for CompanyId in my database, it will skip that Contact in the list it returns. For example, the query var contacts = _context.Contacts.Include(c => c.Company).ToList(); only returns Josh Stone from the following table:

Contacts Table

I am using Entity Framework Core 1.0.0. Any help would be sincerely appreciated.

Robert McKee · Accepted Answer · 2016-10-27 18:25:30Z

35

Supposing that it did actually return mary, what would you expect her CompanyId to be? I would suspect null (what else could it be?), in which case your model is wrong and public int CompanyId { get; set; } should be public int? CompanyId { get; set; }

answered Oct 27, 2016 at 18:25

Robert McKee

21.5k1 gold badge48 silver badges64 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Hamed Hamedi Over a year ago

I am using mysql as db and with your solution, the foreign key would not set as null, instead with 0. And mysql throw exception that the inserted key can not be find in the related table. How can I solve it??

Robert McKee Over a year ago

@HamedHamedi That would be unrelated to the solution. Either you did database first, in which you created the table with a default value, or you did code first, in which case that is set up incorrectly.

Collectives™ on Stack Overflow

Entity Framework Core nullable foreign key

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related