Add a Primary and Foreign Key Relationship in CodeFirst

To complete this task, I am going to create Employee and Department Model Class and let’s see how to make relationship. Following are the two model class.

public class Department
{
   [Key]
   public int DepartmentId { get; set; }

   [Required]
   public string DepartmentName { get; set; }
}

public class Employee
{
   [Key]
   public int EmployeeId { get; set; }

   [Required]
   public string EmployeeName { get; set; }

}

Department Model has primary key as DepartmentId and Employee Model has primary key as EmployeeId. I am going to create a foreign key of DepartmentId in Employee Model.

public class Department
{
   [Key]
   public int DepartmentId { get; set; }

   [Required]
   public string DepartmentName { get; set; }
}

public class Employee
{
   [Key]
   public int EmployeeId { get; set; }

   [Required]
   public string EmployeeName { get; set; }

   // Foreign key
   [Display(Name = "Department")]
   public virtual int DepartmentId { get; set; }

   [ForeignKey("DepartmentId")]
   public virtual Department Departments { get; set; }
}

To create Foreign Key, you need to use ForeignKey attribute with specifying the name of the property as parameter.

[ForeignKey("DepartmentId")]
public virtual Department Departments { get; set; }

You also need to specify the name of the table which is going to participate in relationship. I mean to say, define the Foreign key table.

[Display(Name = "Department")]
public virtual int DepartmentId { get; set; }

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