Adding relational data between two entities

Question

Created May ’17

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Hello, I'm trying to create two classes (database tables) called "Student" and "Course" using the Parse platform. And the intention is to have a relationship between a student and the course. For instance, one student can have many courses. In this case, I'm creating the student "Jeff" with a course "SWEN-500"; then a course "SWEN-500"; and adding the relationship column studentCourse.

However, when I try to create another course for the same student such as

student["course"] = "SWEN-777"

, a different ID for the student (object ID) is created with SWEN-777 as a course. And two students with the same name but different ID's are created with the two courses. But I need to have the same student ID so then I can retrieve one specific student and all his courses he has taken.

func someMethod() {
       
        let student = PFObject(className:"Student")
        student["name"] = "Jeff"
        student["course"] = "SWEN-500"
      
       
        let course = PFObject(className:"Course")
        course["course"] = "SWEN-500"
      
       
        course["studentCourse"] = student
      
        course.saveInBackground()
    }

Any ideas? Thank you in advance.

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Answer 1

Claude31 OP

May ’17

I don't know the Parse platform, so don't know if this proposal could work.

if you declare student["course"] to be a Set of Strings and not a single String, then you could have several courses for a same student.

        let student = PFObject(className:"Student")
        student["name"] = "Jeff"
        student["course"] = "SWEN-500"

to add a course :

student["course"] = student["course"] + ["SWEN-777"]

By the way, if you add the same course to the set, nothing changes ; that's better than array for this purpose.

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