Question

Message POCO:

[Table("Message")]
public class Message
{
    [Key, Column(Order = 0)]
    public Int64 SenderID { get; set; }

    [Key, Column(Order = 1)]
    public Int64 ReceiverID { get; set; }

    public String Body { get; set; }

}

THE SenderID and ReceiverID are foreign keys on UserID in User table

User POCO:

[Table("User")]
public class User
{
    [Key]
    public long UserId { get; set; }
    public string UserName { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

I need a many-to-many relationship: Icollection<Message> Messages property in User POCO and User Sender, User Receiver properties in Message POCO.
How I must do this?

Answer 1

Message POCO:

[Table("Message")]
public class Message
{
    [Key, Column(Order = 0)]
    [ForeignKey("Sender")]
    public Int64 SenderID { get; set; }

    [Key, Column(Order = 1)]
    [ForeignKey("Receiver")]
    public Int64 ReceiverID { get; set; }

    public String Body { get; set; }

    [InverseProperty("SentMessages")]
    public virtual User Sender { get; set; }

    [InverseProperty("ReceivedMessages")]
    public virtual User Receiver { get; set; }
}

User POCO:

[Table("User")]
public class User
{
    [Key]
    public long UserId { get; set; }
    public string UserName { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public virtual ICollection<Message> SentMessages { get; set; }

    public virtual ICollection<Message> ReceivedMessages { get; set; }
}