Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Seed the Database with Test Data

Posted on 2013-11-23
3
Medium Priority
?
356 Views
Last Modified: 2014-01-27
I was wondering if I could get an explanation of the few line bellow from this code that I found from this tutorial...http://www.asp.net/mvc/tutorials/getting-started-with-ef-using-mvc/creating-a-more-complex-data-model-for-an-asp-net-mvc-application

students.ForEach(s => context.Students.AddOrUpdate(p => p.LastName, s));

Explantion?
--------------------------

  var courses = new List<Course>
            {
                new Course {CourseID = 1050, Title = "Chemistry",      Credits = 3,
                  DepartmentID = departments.Single( s => s.Name == "Engineering").DepartmentID,
                  Instructors = new List<Instructor>()
                },


Explantion?
--------------------------



    AddOrUpdateInstructor(context, "Chemistry", "Kapoor");
            AddOrUpdateInstructor(context, "Chemistry", "Harui");


  StudentID = students.Single(s => s.LastName == "Barzdukas").ID,
                    CourseID = courses.Single(c => c.Title == "Chemistry").CourseID,
                    Grade = Grade.B  



Explantion?
--------------------------
foreach (Enrollment e in enrollments)
            {
                var enrollmentInDataBase = context.Enrollments.Where(
                    s =>
                         s.Student.ID == e.StudentID &&
                         s.Course.CourseID == e.CourseID).SingleOrDefault();
                if (enrollmentInDataBase == null)
                {
                    context.Enrollments.Add(e);
                }
            }
            context.SaveChanges();
        }

        void AddOrUpdateInstructor(SchoolContext context, string courseTitle, string instructorName)
        {
            var crs = context.Courses.SingleOrDefault(c => c.Title == courseTitle);
            var inst = crs.Instructors.SingleOrDefault(i => i.LastName == instructorName);
            if (inst == null)
                crs.Instructors.Add(context.Instructors.Single(i => i.LastName == instructorName));
        }
    }



Explantion?
--------------------------
0
Comment
Question by:yguyon28
  • 2
3 Comments
 
LVL 9

Expert Comment

by:QuinnDex
ID: 39672481
the tutorial explains this code and what it is doing, and why you have created an empty list for Instructors.

Read it again go through the code, come back with more specific questions on what you dont understand.
0
 

Author Comment

by:yguyon28
ID: 39672858
I'm not really sure how to understand the sentence bellow....
          students.ForEach(s => context.Students.AddOrUpdate(p => p.LastName, s));
0
 
LVL 9

Accepted Solution

by:
QuinnDex earned 1500 total points
ID: 39682882
works in context with other fields, if it exists already then performs update else adds a new record.
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

In order to hide the "ugly" records selectors (triangles) in the rowheaders, here are some suggestions. Microsoft doesn't have a direct method/property to do it. You can only hide the rowheader column. First solution, the easy way The first sol…
Calculating holidays and working days is a function that is often needed yet it is not one found within the Framework. This article presents one approach to building a working-day calculator for use in .NET.
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …
This lesson discusses how to use a Mainform + Subforms in Microsoft Access to find and enter data for payments on orders. The sample data comes from a custom shop that builds and sells movable storage structures that are delivered to your property. …
Suggested Courses

879 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