Exception when using Update-Database using code first workflow

Question

I have a Movie model and a Genre class as follows:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;

namespace web_template_001.Models
{
    public class Movie
    {
        [Required]
        public int Id { get; set; }
        [Required]
        [StringLength(25)]
        public string Title { get; set; }
        [Required]
        public Genre Genre { get; set; }
        public byte GenreId { get; set; }
        public DateTime DateAdded { get; set; }
        public DateTime ReleaseDate { get; set; }
        public byte NumberInStock { get; set; }
    }

    public class Genre
    {
        [Required]
        public byte Id { get; set; }
        [Required]
        [StringLength(25)]
        public string Name { get; set; }
    }
}

When trying to use Update-Database after creating the migration shown here:

namespace web_template_001.Migrations
{
    using System;
    using System.Data.Entity.Migrations;
    
    public partial class ModifiedMovieProperties : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "dbo.Genres",
                c => new
                    {
                        Id = c.Byte(nullable: false),
                        Name = c.String(nullable: false, maxLength: 25),
                    })
                .PrimaryKey(t => t.Id);
            
            AddColumn("dbo.Movies", "GenreId", c => c.Byte(nullable: false));
            AddColumn("dbo.Movies", "DateAdded", c => c.DateTime(nullable: false));
            AddColumn("dbo.Movies", "ReleaseDate", c => c.DateTime(nullable: false));
            AddColumn("dbo.Movies", "NumberInStock", c => c.Byte(nullable: false));
            CreateIndex("dbo.Movies", "GenreId");
            AddForeignKey("dbo.Movies", "GenreId", "dbo.Genres", "Id", cascadeDelete: true);
        }
        
        public override void Down()
        {
            DropForeignKey("dbo.Movies", "GenreId", "dbo.Genres");
            DropIndex("dbo.Movies", new[] { "GenreId" });
            DropColumn("dbo.Movies", "NumberInStock");
            DropColumn("dbo.Movies", "ReleaseDate");
            DropColumn("dbo.Movies", "DateAdded");
            DropColumn("dbo.Movies", "GenreId");
            DropTable("dbo.Genres");
        }
    }
}

I get this error:

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_dbo.Movies_dbo.Genres_GenreId". The conflict occurred in database "aspnet-web_template_001-20230102051540", table "dbo.Genres", column 'Id'.

Here is the git repo: https://github.com/joshuamitchum89/web_template_001

How do I resolve this issue?

Thank you for taking time to help me.

I have tried to remove the migration and make a new one. Also restarted VS to no end. I have used this approach for other models and classes to link table via foreign keys.

score 0 · Accepted Answer · 2023-01-20 01:41:41Z

0

You need to add the [Key] attribute to the Id properties to both types. See below.

Also, you're key on Gene is a byte, not sure if this is an accident or intentional, but it seems like the former.

 [Key] //fix on both classes
 public int Id { get; set; } 

 //optional if you want to be able to access key
 public int Gene_Id { get; set; }

 [ForeignKey(nameof(Gene_Id))]
 public Genre Genre { get; set; }

edited Jan 20, 2023 at 1:41

answered Jan 20, 2023 at 1:33

user3259797

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2 Comments

Joshua Mitchum Over a year ago

I added both [Key] attributes to each class as you stated and the error did not resolve.

user3259797 Over a year ago

If you can re-link the code, I'll take a look. It's hard to tell without seeing what in the migration that created Movie.

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