I have a category class and it can reference itself(only one level up) as parent category.
When I retrieve the data using dbContext using Entity Framework, the parent relationship is not loaded. How do I go about achieving that?
Here is the class
public class Category
{
[Key]
public int CategoryID { get; set; }
[Display(Name="Category Name")]
public string CategoryName { get; set; }
public int ParentCategoryID { get; set; }
public virtual Category ParentCategory { get; set; }
}
when I retrieve all Category using dbcontext, the ParentCategory is null b/c it didn't join to another Category class with same ID.
Can anyone tell me how do I change db.Category.ToList() method so it also joins the parent child relation at the same time? Thanks
Try Like this
public class Category
{
[Key]
public int CategoryID { get; set; }
[Display(Name="Category Name")]
public string CategoryName { get; set; }
public int? ParentCategoryID { get; set; }
public virtual Category ParentCategory { get; set; }
}
And in your Context class,
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Category>().
HasOptional(e => e.ParentCategory).
WithMany().
HasForeignKey(m => m.ParentCategoryID);
}
The ParentCategoryID has to be nullable because the root category will not have a parent and EF needs to assign null to it.
public class Category
{
[Key]
public int CategoryID { get; set; }
[Display(Name="Category Name")]
public string CategoryName { get; set; }
public int? ParentCategoryID { get; set; }
public virtual Category ParentCategory { get; set; }
}
