Entity Data Modeling Fundamentals - Entity Framework 6 Recipes - page 29

2-5. Modeling a Self-Referencing Relationship with
a Code-First Approach
Problem
You have a table that references itself, and you want to model this as an entity with a self-referencing association using
a Code-First approach.

Solution
Let's say that you have a self-referencing table that's like the one shown in the database diagram in Figure 2-14 .

Figure 2-14. A self-referencing table

To create a model and import this table and the self-referencing relationship into the model, do the following:

1. Create a new class that inherits from DbContext in your project.

Use the code in Listing 2-5 to create the PictureCategory POCO entity.

2.

Listing 2-5. Creating the PictureCategory POCO Entity

public class PictureCategory
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int CategoryId { get; private set; }
public string Name { get; set; }
public int? ParentCategoryId { get; private set; }

[ForeignKey("ParentCategoryId")]
public PictureCategory ParentCategory { get; set; }

public List<PictureCategory> Subcategories { get; set; }

public PictureCategory()
{
Subcategories = new List<PictureCategory>();
}
}