?
Solved

.MapRightKey

Posted on 2014-02-23
2
Medium Priority
?
197 Views
Last Modified: 2014-03-03
Trying to understand what the following code mean.... MapLeftKey???

Map(t => t.MapLeftKey("CourseID")
                 .MapRightKey("InstructorID")
                 .ToTable("CourseInstructor"));


using ContosoUniversity.Models;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;

namespace ContosoUniversity.DAL
{
   public class SchoolContext : DbContext
   {
      public DbSet<Course> Courses { get; set; }
      public DbSet<Department> Departments { get; set; }
      public DbSet<Enrollment> Enrollments { get; set; }
      public DbSet<Instructor> Instructors { get; set; }
      public DbSet<Student> Students { get; set; }
      public DbSet<OfficeAssignment> OfficeAssignments { get; set; }

      protected override void OnModelCreating(DbModelBuilder modelBuilder)
      {
         modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

         modelBuilder.Entity<Course>()
             .HasMany(c => c.Instructors).WithMany(i => i.Courses)
             .Map(t => t.MapLeftKey("CourseID")
                 .MapRightKey("InstructorID")
                 .ToTable("CourseInstructor"));
      }
   }
}
0
Comment
Question by:yguyon28
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 

Author Comment

by:yguyon28
ID: 39881239
modelBuilder.Entity<Course>()
             .HasMany(c => c.Instructors).WithMany(i => i.Courses)
             .Map(t => t.MapLeftKey("CourseID")
                 .MapRightKey("InstructorID")
                 .ToTable("CourseInstructor"));

Does this actually create a table CourseInstructor?
0
 
LVL 63

Accepted Solution

by:
Fernando Soto earned 1500 total points
ID: 39881253
Hi yguyon28;

This is building a many-to-many relationship from the Course table, the LeftKey, to a juction table called CourseInstructor, created in the database only, to the Instructor table, the RightKey side.

modelBuilder
    // Defines the table we are defining
    .Entity<Course>()
    // Course has a collection called Instructors and that Instructor has a collection of Courses.
    .HasMany(c => c.Instructors).WithMany(i => i.Courses)
    // The next three statements define the Juction table
    // The first entry in the table is the primary key from Course table identified as MapLeftKey
    .Map(t => t.MapLeftKey("CourseID")
    // The second entry in the table is the primary key from Instructor table identified as MapRightKey    
    .MapRightKey("InstructorID")
    // This is the table name for the junction table
    .ToTable("CourseInstructor"));
  

Open in new window

0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

We all know that functional code is the leg that any good program stands on when it comes right down to it, however, if your program lacks a good user interface your product may not have the appeal needed to keep your customers happy. This issue can…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …
In this video, Percona Director of Solution Engineering Jon Tobin discusses the function and features of Percona Server for MongoDB. How Percona can help Percona can help you determine if Percona Server for MongoDB is the right solution for …
Suggested Courses

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question