Specify the column to use when joining

Question

I have some tables to specify standard email messages and the addresses from which they should be sent:

Email.Message
-------------
MessageId
Name
FromAddressId

Email.Address
-------------
AddressId

These tables are modeled in code using these classes:

public class EmailAddress
{
    public int AddressId { get; set; }
}

public class EmailMessage
{
    public int MessageId { get; set; }
    public string Name { get; set; }
    public int FromAddressId { get; set; }
    public virtual EmailAddress FromAddress { get; set; }
}

var message = Db.EmailMessages
                .Where(m => m.Name == name)
                .Include(m => m.FromAddress)
                .SingleOrDefault();

I am using Fluent API to specify the relationship:

internal class EmailMessageMap : EntityTypeConfiguration<EmailMessage>
{
    public EmailMessageMap()
    {
        ToTable("Message", "Email");
        HasKey(p => p.MessageId);
        // What do I put here?
    }
}

How do I set up the join to use the FromAddressId of my EmailMessage class? I've tried these options:

HasRequired(p => p.FromAddress).WithRequiredPrincipal(); // uses LEFT OUTER JOIN
HasRequired(p => p.FromAddress).WithRequiredDependent(); // uses INNER JOIN

These cause the SQL that gets created to use either a LEFT OUTER JOIN or an INNER JOIN, but they always try to join Message.MessageId to Address.AddressId, which is incorrect. How do I make it use the correct column (FromAddressId)? I need to have something to replace the // What do I put here?, because otherwise I get the following exception:

Invalid column name 'FromAddress_AddressId'

EDIT: I can place a [ForeignKey("FromAddressId")] on top of the FromAddress property and it works:

[Extent1].[FromAddressId] = [Extent2].[AddressId]

Progress! Now, how do I do this in Fluent API?

Answer 1

Now, how do I do this in Fluent API?

HasRequired(p => p.FromAddress)
.WithMany()
.HasForeignKey(p => p.FromAddressId);