Foreign Key in Entity Framework

Question

I am reading through this tutorial.... ASP.NET Code First MVC Tutorial

In this example, Student Class has the "ID" property.

Enrollment Class has "StudentID" property.

Now, If all the additional definition in Enrollment class says,

                public virtual Student Student { get; set; }

Just by that statement, will the EF know that StudentID is foreign key?

My confusion is, in the Student Table, property name is "ID" .. Say in the Enrollment Class, instead of StudentID, I call it.... Student_ID....will the EF still correlate Student.ID as the same as Enrollment.Student_ID and establish foreign key? Does it just need the "Student" string in a property name in Enrollment class to establish relationship?

Code snippets from the site...

       using System;
       using System.Collections.Generic;

       namespace ContosoUniversity.Models
       {
           public class Student
           {
               public int ID { get; set; }
               public string LastName { get; set; }
               public string FirstMidName { get; set; }
               public DateTime EnrollmentDate { get; set; }

               public virtual ICollection<Enrollment> Enrollments { get; set; }
           }
       }



       namespace ContosoUniversity.Models
       {
           public enum Grade
           {
               A, B, C, D, F
           }

           public class Enrollment
           {
               public int EnrollmentID { get; set; }
               public int CourseID { get; set; }
               public int StudentID { get; set; }
               public Grade? Grade { get; set; }

               public virtual Course Course { get; set; }
               public virtual Student Student { get; set; }
           }
       }

Here is a very good explanation on this topic : http://stackoverflow.com/questions/5542864/how-should-i-declare-foreign-key-relationships-using-code-first-entity-framework — Leron, Mar 13 '14 at 16:03
That link from Leron is a good one. Basically you could mark your ID property with `[ForeignKey("")]` attribute. — Rosdi Kasim, Mar 13 '14 at 16:25
Thanks guys. I read through the link by leron and it was helpful as well. — buzcrawl, Mar 13 '14 at 17:05

score 0 · Accepted Answer · answered Mar 13 '14 at 16:18

Entity Framework follows a "Convention over configuration" approach with regards to Foreign Keys.

"Any property with the same data type as the principal primary key property and with a name that follows one of the following formats represents a foreign key for the relationship: ‘[navigation property name][principal primary key property name]’, ‘[principal class name][primary key property name]’, or ‘[principal primary key property name]’. If multiple matches are found then precedence is given in the order listed above. Foreign key detection is not case sensitive. "

Source: http://msdn.microsoft.com/en-us/data/jj679962.aspx

So as long as you follow one of the conventions then it will infer the Foreign Key for you. If you don't follow one of the conventions, then you will have to explicitly state the relationship through a configuration.

Thank you! Really helpful to understand. – buzcrawl Mar 13 '14 at 17:05 — buzcrawl, Mar 13 '14 at 17:05

Foreign Key in Entity Framework

1 Answers1