Creating model from existing table in Entity Framework

Question

I have many-to-many relation Student-Course which I realised using virtual collection list and I got the next generated migration code :

 CreateTable(
            "dbo.PersonCourses",
            c => new
                {
                    Person_Id = c.Int(nullable: false),
                    Course_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => new { t.Person_Id, t.Course_Id })
            .ForeignKey("dbo.People", t => t.Person_Id, cascadeDelete: true)
            .ForeignKey("dbo.Courses", t => t.Course_Id, cascadeDelete: true)
            .Index(t => t.Person_Id)
            .Index(t => t.Course_Id);

Now I want to map table PersonCourses to some C# class and I wrote

[Table("PersonCourses")]
public class PersonCourses
{

    [ForeignKey("Person")]
    [Required]
    public int PersonId { get; set; }

    [ForeignKey("Course")]
    [Required]
    public int CourseId { get; set; }
}

but it fails with : "PersonCourses" has no key defined.Define the key for this EntityType.

Frebin Francis · Accepted Answer · 2015-02-23 12:45:01Z

1

You should add attribute [Key] property PersonCoursesId:

public partial class Category
        {
            [Key]
            public int PersonCoursesId { get; set; }    

            [ForeignKey("Person")]    
            public int PersonId { get; set; }

            [ForeignKey("Course")]   
            public int CourseId { get; set; }            
        }

The problem is that EF can work only when it knows primary key of table. By default EF recognize as primary key property with name Id. If your table has another primary key, you can mark it with attribute [Key] or set Key with fluent configuration.

Hope this helps.

answered Feb 23, 2015 at 12:45

Frebin Francis

1,9151 gold badge12 silver badges19 bronze badges

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

Comments

Alex · Accepted Answer · 2015-02-23 12:49:25Z

1

You need the [Key] attribute above properties that make up the primary key. For composite primary keys you also need to specify a column order. See https://msdn.microsoft.com/en-us/data/jj591583.aspx#Composite

answered Feb 23, 2015 at 12:49

Alex

1361 silver badge8 bronze badges

Collectives™ on Stack Overflow

Creating model from existing table in Entity Framework

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related