How to define two foreign keys that are not composite with Data Annotations in database first EF?

Question

In SQL, I have a table with two columns that both map to the same primary key in another table. The easiest way to explain is using the table constraints:

ALTER TABLE [dbo].[sls_n_Promotion]  WITH CHECK ADD  CONSTRAINT [FK_SlsPromotion_SlsPromotionTradeSpendType] FOREIGN KEY([TradeSpendID])
REFERENCES [dbo].[sls_a_PromotionTradeSpendType] ([ID])
GO

ALTER TABLE [dbo].[sls_n_Promotion] CHECK CONSTRAINT [FK_SlsPromotion_SlsPromotionTradeSpendType]
GO

ALTER TABLE [dbo].[sls_n_Promotion]  WITH CHECK ADD  CONSTRAINT [FK_SlsPromotion_SlsPromotionTradeSpendType2] FOREIGN KEY([TradeSpendSubID])
REFERENCES [dbo].[sls_a_PromotionTradeSpendType] ([ID])
GO

ALTER TABLE [dbo].[sls_n_Promotion] CHECK CONSTRAINT [FK_SlsPromotion_SlsPromotionTradeSpendType2]
GO

I'm using database first, and I have created Promotion.partial.cs. In this partial class, I'm struggling to get the Data Attributes set correctly for 'TradeSpendID' and 'TradeSpendSubID'. This is what I currently have:

[Display(Name="Trade Spend Type")]
[Column("TradeSpendID")]
[ForeignKey("PromotionTradeSpendType")]
int? TradeSpendId { get; set; }

[Display(Name = "Trade Spend Sub Type")]
[Column("TradeSpendSubID")]
[ForeignKey("PromotionTradeSpendType")]
int? TradeSpendSubId { get; set; }

When I go to create a Controller using scaffolding, I get the error:

Unable to determine a composite foreign key ordering for foreign key on type...

This isn't a composite foreign key.

Question: How do I use Data Attributes for the foreign keys on those 2 properties?

Answer 1

There should be two Navigation Properties. EG

[Display(Name="Trade Spend Type")]
[Column("TradeSpendID")]
[ForeignKey("PromotionTradeSpendType")]
public int? TradeSpendId { get; set; }
public virtual PromotionTradeSpendType PromotionTradeSpendType { get; set; }

[Display(Name = "Trade Spend Sub Type")]
[Column("TradeSpendSubID")]
[ForeignKey("PromotionTradeSpendSubType")]
public int? TradeSpendSubId { get; set; }
public virtual PromotionTradeSpendType PromotionTradeSpendSubType { get; set; }