Foreign Key in Code First Entity Framework

Question

My question is this. Let's say I have a Category class and Product class. And they are implemented like this : Category :

public class Category { public Category() { this.Products = new ObservableCollection<Product>(); } public int CategoryId { get; set; } public string Name { get; set; } public virtual ObservableCollection<Product> Products { get; private set; } }

And Product :

public class Product { public int ProductId { get; set; } public string Name { get; set; } public int CategoryId { get; set; } public virtual Category Category { get; set; } }

My question is this. If their id names were both "Id", how could I set the same relationship between Category and Product? In this example I can easily put CategoryId in product because the IDs have different names. What if they had the same name? What should I do? Thanks.

You haven't, but how can I achieve the same relationship? Is there anything extra to do? Both Category and Product is inherited from the same base class. And the class has "Id". — jason
– jason, Commented Jul 7, 2014 at 7:54
Have you had a look at the msdn.microsoft.com/en-gb/data/jj591620.aspx article. Search for 'Configuring a Many-to-Many Relationship'. You need to use the modelBuilder to map the relationship. — Dr Schizo
– Dr Schizo, Commented Jul 7, 2014 at 7:54
You don't need them to have the same name. If you want the name in the database tables to be identical, you can do that by using the [Column(Name="ID")] attribute to decorate your ProductId and CategoryId fields in their respective class definitions. — Alex Barac
– Alex Barac, Commented Jul 7, 2014 at 7:57

Yuliam Chandra · Accepted Answer · 2014-07-07 08:11:12Z

1

I think just renaming their Id(s) to "Id" work perfectly as you expected.

public class Category { public Category() { this.Products = new ObservableCollection<Product>(); } public int Id { get; set; } public string Name { get; set; } public virtual ObservableCollection<Product> Products { get; private set; } } public class Product { public int Id { get; set; } public string Name { get; set; } public int CategoryId { get; set; } public virtual Category Category { get; set; } }

Result

Result from database

answered Jul 7, 2014 at 8:11

Yuliam Chandra

14.7k12 gold badges56 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

jason Over a year ago

So you mean there is nothing additional thing to do to set the relationship?

Yuliam Chandra Over a year ago

you need to understand the convention, but if you want different name as navigation property you can use ForeignKey attribute or FluentApi

Yuliam Chandra Over a year ago

the convention fits your requirement, so yes, there is nothing to set up

jason Over a year ago

How does it know thaat? Categories_CategoryId is same as the Id of categories? Thanks.

Yuliam Chandra Over a year ago

in this case by adding Category::Products(array) creates the relationship, if you don't have Product::CategoryId, then EF will create Category_Id column in Products table

|

Collectives™ on Stack Overflow

Foreign Key in Code First Entity Framework

1 Answer 1

Result

7 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Result

7 Comments

Linked

Related