Error messages for generating schedules

[rachelconn]

Description

Adds messages describing what went wrong when generate schedules doesn't return any schedules. I'd appreciate if everyone could try to think of other reason generating schedules might fail so we can be sure these error messages are accurate and cover everything that could possibly go wrong.

Rationale

There are a couple assumptions I make to avoid making extra queries just to check if sections still exist in the queryset:

• Courses have sections for the term given (since when searching for courses it only gives courses with sections in the current term, this should be fine)
• Web/honors filters don't result in an empty queryset (I made changes to make sure this assumption is always valid on the frontend, as before when the course changed it didn't change your existing choice for web/honors)

With these assumptions, these are the three ways generating schedules can fail and their messages:

_NO_SECTIONS_WITH_SEATS = (
    'None of the sections you selected for {subject} {course_num} have available seats.'
)
_NO_SECTIONS_MATCH_AVAILABILITIES = (
    'No sections for {subject} {course_num} are compatible with your available times. '
    'Either select more sections, or remove some of your busy times.'
)
_NO_SCHEDULES_POSSIBLE = 'No schedules are possible with your selected constraints.'

There's also the possibility that the call fails (since the server is down or the schedules are malformatted), for this case I added another message to the frontend saying that something went wrong.

I also refactored the section filters on the frontend to use an enum for consistency, since it's always bothered me that we use explicit values and this PR is vaguely related to section filters.

How to test

Try to generate schedules with various constraints that may or may not result in no schedules being generated. I think I was pretty thorough with the ways the call can fail, but there's always the possibility I missed something.

Screenshots

Previous error message:

Example new error messages:

Related tasks

Closes #399.

[rachelconn]

Other ideas for the no schedules possible text:

• It's impossible to make any schedules without overlapping classes and your constraints. Either select more sections or remove some of your busy times.
• Your constraints are too strict to create any valid schedules. Either select more sections or remove some of your busy times.

What does everyone think? I think these are clear enough to tell the user both what went wrong and how to fix it.

[gannonprudhomme]

will review this again, but some minor comments I had the other day

[rachelconn]

I found 2 more failure cases (and by that I mean I found one and the other is one I missed from the issue Gannon made), here are the messages since they're pretty self explanatory:

[firejake308]

I think that was separate PR

[rachelconn]

I think that was separate PR

Correct, we don't have a mockup for a new design and I wanted this PR to be focused on the functionality itself rather than the styling of how we display it

[gannonprudhomme]

Still messing with this & will probs continue later, but one thing I noticed is that if there's a conflict between one thing it'll catch it 100% of the time (e.g. if your availabilities are completely knocking out a single course), but if there's like 2 sections in one course and 2 sections in another course and an availability blocks off one each (and the remaining sections intersect with each other), it's going to give the generic "No schedules are possible", even though removing the availability would result in a possible schedule.

Here's a super specific example of it:

• Term: 202031
• Course 1: CSCE 482. Section customization level, selected sections 900 and 901
• Course 2: ACCT 209. Section customization level, selected sections 501 and 502
• Include full sections selected

Generate schedules and you'll see there are two available ones

But if you block off from 8:30 - 12:00 on Monday it'll give you the generic "no schedules are possible", even though removing the availability would fix it.

[gannonprudhomme]

Also anytime it mentions a specific section as the reason, you should bold the section text so you immediately focus on it.

[rachelconn]

Also anytime it mentions a specific section as the reason, you should bold the section text so you immediately focus on it.

Do you still want me to implement this? We don't post-process text anywhere else so I'm wondering how you want me to go about doing it

Still messing with this & will probs continue later, but one thing I noticed is that if there's a conflict between one thing it'll catch it 100% of the time (e.g. if your availabilities are completely knocking out a single course), but if there's like 2 sections in one course and 2 sections in another course and an availability blocks off one each (and the remaining sections intersect with each other), it's going to give the generic "No schedules are possible", even though removing the availability would result in a possible schedule.

Since you could either add more sections or remove busy times to fix the issue in most cases and narrowing it down more than that is impossible unless all sections are selected for all classes on your schedule, I'm not going to implement this

I'd also appreciate feedback from someone on what to change the generic error message to (see my earlier comment)

[gannonprudhomme]

Do you still want me to implement this? We don't post-process text anywhere else so I'm wondering how you want me to go about doing it

If it's possible yeah, I think it would be beneficial

I'd also appreciate feedback from someone on what to change the generic error message to (see my earlier comment)

Your constraints are too strict to create any valid schedules. Either select more sections or remove some of your busy times. This one sounds better

[firejake308]

Your constraints are too strict to create any valid schedules. Either select more sections or remove some of your busy times.

I like how the second half gives suggestions for how to fix it, but the first part feels a little confrontational to me. I would try No schedules found. Either select more sections or remove some of your busy times.

[gannonprudhomme]

the first part feels a little confrontational to me.

Agreed, definitely cause the usage of your.

I would try No schedules found. Either select more sections or remove some of your busy times.

I think No schedules possible for the first part would be slightly better - that way they know it's not us ("rev registration"), it's their schedule/constraints that are the problem

[rachelconn]

Do you still want me to implement this? We don't post-process text anywhere else so I'm wondering how you want me to go about doing it

If it's possible yeah, I think it would be beneficial

I don't think it's that helpful and I'm not sure how I would go about doing it, so for now I'm going to leave it as-is. We can make it into a separate issue if we decide that we want it to work like that, but I don't want it to hold up this getting merged before launch

Also I changed the generic message to:
No schedules possible. Either select more sections or remove some of your busy times.

So if we agree the bold text isn't a big enough deal to prevent this from getting merged this should be ready for review

[gannonprudhomme]

Didn't do any testing just looked at code, so will look at this again later today (hopefully)

[gannonprudhomme]

Suggested change

	// Fetches scheduler/generate. If something goes wrong or no schedules can be generated,
	// throws an error with a message indicating what happened.
	/** Fetches scheduler/generate. If something goes wrong or no schedules can be generated,
	throws an error with a message indicating what happened. */

So it shows up as a doc when you hover over the function

[gannonprudhomme]

Should we be switching between available and busy here? I get why you did it but just wanted to double check

[rachelconn]

Yeah I was thinking about that as I wrote this, and it doesn't really make sense if it uses one or the other so I left it like this

[gannonprudhomme]

nitpick lol

Suggested change

	))
	return sections
	))
	return sections

[gannonprudhomme]

Suggested change

print(expected)

[gannonprudhomme]

Also need to merge master into this, presumably b/c #417

[rachelconn]

Changes made except the chained .thens, and I merged in master

[gannonprudhomme]

If possible, I'd like you to at least investigate into why the snackbar is appearing so large:

And try to make it smaller - I seriously hate how large this is. Ik we're going to eventually move away from the snackbar, but since that's probs a ways away I still want this to look good

[rachelconn]

I made a theme override to put the message and actions on the same line (since the old behavior is what material ui wants to do by default), also rebased with master

Addressed