EF-外键关系中组合键的一部分

Question

I am attempting to utilise the "Code first from database" feature of ADO.NET. The generation works successfully and outputs all of my desired models. I have several EF models that both have composite keys as primary keys. I've given 2 such models as an example below.

public partial class LabRole
{
    public LabRole()
    {
        LabRolePermissions = new HashSet<LabRolePermission>();
        LabUserRoles = new HashSet<LabUserRole>();
        RoleSubscriptions = new HashSet<RoleSubscription>();
    }

    [Key]
    [Column(Order = 0)]
    [StringLength(50)]
    public string RoleID { get; set; }

    [Key]
    [Column(Order = 1)]
    [StringLength(50)]
    public string LabID { get; set; }

    public virtual ICollection<LabRolePermission> LabRolePermissions { get; set; }

    public virtual Lab Lab { get; set; }

    public virtual ICollection<LabUserRole> LabUserRoles { get; set; }

    public virtual ICollection<RoleSubscription> RoleSubscriptions { get; set; }
}

And:

public partial class LabRolePermission
{
    [Key]
    [Column(Order = 0)]
    [StringLength(50)]
    public string LabID { get; set; }

    [Key]
    [Column(Order = 1)]
    [StringLength(50)]
    public string RoleID { get; set; }

    [Key]
    [Column(Order = 2)]
    [StringLength(50)]
    public string PermissionID { get; set; }

    public virtual Lab Lab { get; set; }

    public virtual LabRole LabRole { get; set; }

    public virtual Permission Permission { get; set; }
}

This then has the foreign key relationship set on it:

modelBuilder.Entity<LabRole>()
            .HasMany(e => e.LabRolePermissions)
            .WithRequired(e => e.LabRole)
            .HasForeignKey(e => new { e.RoleID, e.LabID })
            .WillCascadeOnDelete(false);

I run add-migration and an initial migration script is generated successfully. However, when I try and access something in the context it errors:

Problem in mapping fragments starting at lines 119, 128: Foreign key constraint 'LabRole_LabRolePermissions' from table LabRolePermission (LabID, RoleID) to table LabRole (RoleID, LabID):: Insufficient mapping: Foreign key must be mapped to some AssociationSet or EntitySets participating in a foreign key association on the conceptual side.

Could someone please explain why this is happening and/or the solution to this problem.

Answer 1

OK I have found the answer. If I remove the use of data annotations for specifying keys and instead specify them using fluent API the generated database functions as expected.

For example, if I change my models to:

public partial class LabRole
{
    public LabRole()
    {
        LabRolePermissions = new HashSet<LabRolePermission>();
        LabUserRoles = new HashSet<LabUserRole>();
        RoleSubscriptions = new HashSet<RoleSubscription>();
    }

    [StringLength(50)]
    public string RoleID { get; set; }

    [StringLength(50)]
    public string LabID { get; set; }

    public virtual ICollection<LabRolePermission> LabRolePermissions { get; set; }

    public virtual Lab Lab { get; set; }

    public virtual ICollection<LabUserRole> LabUserRoles { get; set; }

    public virtual ICollection<RoleSubscription> RoleSubscriptions { get; set; }
}

And:

public partial class LabRolePermission
{
    [StringLength(50)]
    public string LabID { get; set; }

    [StringLength(50)]
    public string RoleID { get; set; }

    [StringLength(50)]
    public string PermissionID { get; set; }

    public virtual Lab Lab { get; set; }

    public virtual LabRole LabRole { get; set; }

    public virtual Permission Permission { get; set; }
}

Then define the keys using Fluent ie

modelBuilder.Entity<LabRolePermission>().HasKey(e => new { e.LabID, e.RoleID, e.PermissionID });

modelBuilder.Entity<LabRole>().HasKey(e => new { e.RoleID, e.LabID });

I can access the database without any issues. I'm not really sure why this works but it does. Hope this helps someone in the future.