Grades are not updated when changing grading from “Teacher grades students“ to “Use ratings”

[kiratskitizing]

Improvement for when grade/rating is awarded to a student post and then teacher changes the grade / grading setting value.

Replication:
As instructor:

• Create new oublog
  • add new ou blog
  • set
    • Name - {anything}
    • grade -> grading = teacher grades students
    • ratings = average
  • Save and display
    As student via loginas:

1. Create a new blog entry with any content

As an instructor:

1. set a rating for that blog entry (for example 50)
2. Check grades (grade page page) to see that there is no mark for OU Blog
3. Go to OU Blog settings then change grading to use ratings
4. Check grades for ou blog

OBSERVED BEHAVIOR
Grades are not updated after updating the OU Blog activities grade settings from "Teacher grades students“ to “Use ratings”

I believe this is very similar to https://tracker.moodle.org/browse/MDL-76764. The developer there suggested the following:

• Prevent the user from changing the aggregate type once we have grades
• Deal with the change of Aggregate type dynamically (better but probably more difficult)

Thanks for looking into this.