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C# Entity Framework Basics CRUD Operations Updating an Entity

Posted by Amy Shah
Amy Shah
25,337 Points

i might be very close now

In Repository.cs update the UpdateCourse method to persist changes to a course to the database. Instantiate an instance of the Context class within a using statement Call the Attach method on the context's Courses DbSet property to attach the course parameter to the context Retrieve the course's entry using the context's Entry method and set its state to "Modified" Call the context's SaveChanges method to persist the changes to the database

I am not sure I set the state to modified correctly

Repository.cs 
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;

namespace Treehouse.CodeChallenges
{
    public static class Repository
    {
        public static List<Course> GetCourses()
        {
            using (var context = new Context())
            {
                return context.Courses
                              .OrderBy(c => c.Teacher.LastName)
                              .ThenBy(c => c.Teacher.FirstName)
                              .ToList();
            }
        }

        public static List<Course> GetCoursesByTeacher(string lastName)
        {
            using (var context = new Context())
            {
                return context.Courses
                              .Where(c => c.Teacher.LastName == lastName)
                              .ToList();
            }
        }

        public static Course GetCourse(int id)
        {
            using (var context = new Context())
            {
                return context.Courses
                              .Include(c => c.Teacher)
                              .SingleOrDefault(c => c.Id == id);
            }
        }

        public static void AddCourse(Course course)
        {
            using (var context = new Context())
            {
                context.Courses.Add(course);
                context.SaveChanges();
            }
        }

        public static void UpdateCourse(Course course)
        {
            // TODO
             using (var context = new Context())
            {
                 context.Courses.Attach(course)
                                .Entry("Modified");
                                context.SaveChanges();
        }
    }
}

1 Answer

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

Well, maybe close...er anyway.

  • it looks like your're missing the close brace of your using block
  • like SaveChanges, Entry is a method of the context itself
  • the Entry method returns a DbEntityEntry object that has a State property
  • the State property can be set, but not using a string
  • check the EntityState documentation for more info on possible values.