Converting comma delimited items to an entity using edmx

Question

Is it possible to convert the column (stored as comma delimited) to be presented in the edmx designer as another entity?

table structure

student
  id
  name
  subjects << this is the comma delimited column (1,2,3,10)

subject
  id
  name

EDMX designer structure would be

student 
  id
  name

student_subject
  studentId
  subjectid

subject
  id
  name   

If so, can someone point me on how to do it on EF designer.

NOTE: I cannot change the table structure and I'm using database first

thanks

Answer 1

There is no way to do this. Worse: in SQL it might be possible to fetch the subjects with an IN clause, but with linq you haven't even got that option. I'm afraid what's left is a painstaking linq-to-objects operation where you first grab the Student from the database, then parse the subjects in an int array, and finally grab the Subjects with a Contains query:

var subjectIds = student.Subjects
    .Split(",".ToCharArray(), StringSplitOptions.RemoveEmptyEntries)
    .Select (x => int.Parse(x));

var subjects = context.Subjects.Where(s => subjectIds.Contains(s.Id));

(And don't forget to send the architect as student to a course with subject 'Data base design')