EF Core OnDelete restrict adds additional column - entity-framework

Question

I have models in a many-to-many relationship:
User
public class User
{
public int Id { get; set; }
public int CompanyId { get; set; }
[Required]
[StringLength(100)]
public string Username { get; set; }
[Required]
public string PasswordHash { get; set; }
[ForeignKey("CompanyId")]
public Company Company { get; set; }
public ICollection<UserRole> UserRoles { get; set; }
}
Role
public class Role
{
public int Id { get; set; }
public int CompanyId { get; set; }
[Required]
[StringLength(100)]
public string Name { get; set; }
[StringLength(500)]
public string Description { get; set; }
[ForeignKey("CompanyId")]
public Company Company { get; set; }
public ICollection<RolePrivilege> RolePrivileges { get; set; }
}
UserRole
public class UserRole
{
public int Id { get; set; }
public int UserId { get; set; }
public int RoleId { get; set; }
[ForeignKey("UserId")]
public User User { get; set; }
[ForeignKey("RoleId")]
public Role Role { get; set; }
}
When I created migrations and then tried update-database, it threw an error of multiple cascade paths. The solution to this was to make On Delete, No Action so I added this in OnModelCreating:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<UserRole>()
.HasIndex(e => new { e.UserId, e.RoleId })
.IsUnique();
modelBuilder.Entity<UserRole>()
.HasOne(e => e.User)
.WithMany()
.OnDelete(DeleteBehavior.Restrict);
modelBuilder.Entity<UserRole>().ToTable("UserRoles");
}
Now the tables are created but one thing that I wasn't expecting is its making an extra column. The migration code looks like this after generating:
migrationBuilder.CreateTable(
name: "UserRoles",
columns: table => new
{
Id = table.Column<int>(type: "int", nullable: false)
.Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
RoleId = table.Column<int>(type: "int", nullable: false),
UserId = table.Column<int>(type: "int", nullable: false),
UserId1 = table.Column<int>(type: "int", nullable: true)
},
constraints: table =>
{
table.PrimaryKey("PK_UserRoles", x => x.Id);
table.ForeignKey(
name: "FK_UserRoles_Roles_RoleId",
column: x => x.RoleId,
principalTable: "Roles",
principalColumn: "Id",
onDelete: ReferentialAction.Cascade);
table.ForeignKey(
name: "FK_UserRoles_Users_UserId",
column: x => x.UserId,
principalTable: "Users",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
table.ForeignKey(
name: "FK_UserRoles_Users_UserId1",
column: x => x.UserId1,
principalTable: "Users",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
});
As you can see, it added an extra column, UserId1.
What am I doing wrong or how do I prevent this from happening?

Answer 1

This is a result of a typical relationship fluent configuration mistake - using a parameterless overload of Has / With (effectively telling EF that there is no corresponding navigation property) while actually a navigation property exists. In that case EF will map the missing navigation property to another relationship with no navigation property at the other end and default by convention FK property/column name.
To fix the issue, make sure to use the correct overloads which represent the presence/absence of a navigation property (and update them according in case you add/remove navigation property). In your case, replace
.WithMany()
with
.WithMany(e => e.UserRoles)