MongoDB: Editing Element In Array - arrays

Question

I am wanting to edit an element that might exist in multiple arrays in a collection.
public class Class
{
[BsonId]
public Guid Id { get; set;}
public string Name {get; set;}
public List<Student> Students {get; set;}
}
public class Student
{
[BsonId]
public Guid Id {get; set;}
public string Name {get; set;}
public string Grade {get; set;}
}
Then my class collection would look like
{
"_id" : NUUID("..."),
"Name" : "Computer Science",
"Students" : [
{
"_id" : NUUID("..."),
"Name" : "Chris"
"Grade" : "A"
},
{
"_id" : NUUID("..."),
"Name" : "Bob"
"Grade" : "B"
}
}
And my student collection would look like
{
"_id" : NUUID("..."),
"Name" : "Chris Eastwood"
"Grade": "C
}
Now when a student updates his information I want his information to be updated in each class.
I was trying to do:
// given student that has been edited
var query = Query.EQ("Students._id", student.Id);
var update = Update<Class>
.Pull(c => c.Students, x => x.EQ(q => q.Id, student.Id))
.Push(c => c.Students, student)
Context.Class.Update(query,update,UpdateFlags.Multi);
But that does not work since you "cannot update Students and Students at the same time"
I was wondering is there a way to just update all that student in each array for each Class that contains that Student?
Thanks!

Answer 1

I'm not familiar with the c# driver, but this is the query that you are looking for:
db.classes.update({
'Students._id': some_student_id,
}, {
$set: {
'Students.$.property': some_value
}
},{
multi: true
});
The key concept that you are looking for is the positional $ operator. It is the index of the object that matched in the query.