Question

At start i wanted to mention that i’ve been fighting this thing for a few days and tried many of the answers more or less related to this problem. Yet I could not resolve it.

I have two classes that represent tables in a DB. These are the existing tables used by legacy application and I cannot change them.

Message can have multiple MessageRecipients.

Environment: MVC3, EF4.1

Classes are:

public class Message
{
    [ForeignKey("MessageReciepients")]
    public virtual int MessageID { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
    public DateTime Recieved { get; set; }
    [ForeignKey("User")]
    public int AuthorUserID { get; set; }

    //P\\ Navigation properties
    public virtual IList<MessageRecipient> MessageReciepients { get; set; }
    public virtual User User { get; set; }
}

public class MessageRecipient
{
    //[Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int MessageID { get; set; }
    public int UserID { get; set; }
    public bool Read { get; set; }
    public bool Important { get; set; }
    public bool Deleted { get; set; }
    public bool Destroyed { get; set; }

    //P\\ Navigation Properties
    public virtual User User { get; set; }
}

The error I have is:

The foreign key component ‘MessageID’ is not a declared property on
type ‘MessageRecipient’. Verify that it has not been explicitly
excluded from the model and that it is a valid primitive property.

How to correctly map these classes, relationships to load the recipients of a message?

I can add that the navigation property User works correctly for a Message and loads a User’s data correctly.

I’m not too experienced with .NET and I learn while doing this.
I tried some EF API config to map these i tried swearing at it, curse it, and been close to cry and pray at the same time. No Joy!!

I would really appreciate the help.

Answer 1

It turned out that the problem was with the composite key that i needed to use and it all could be solved with some attributes:

This is how it looks now:

public class Message
{
    public int MessageID { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
    public DateTime Recieved { get; set; }

    [ForeignKey("User")]
    public int AuthorUserID { get; set; }

    //P\\ Navigation properties
    public virtual ICollection<MessageRecipient> MessageRecipients { get; set; }
    public virtual User User { get; set; }
}

public class MessageRecipient
{
    [Key, Column(Order=0), ForeignKey("User")]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int UserID { get; set; }

    [Key, Column(Order = 1)]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int MessageID { get; set; }

    public bool Read { get; set; }
    public bool Important { get; set; }
    public bool Deleted { get; set; }
    public bool Destroyed { get; set; }

    //P\\ Navigation Properties
    public virtual User User { get; set; }
}