validation added to NumericalInput to just accept numerical values on block creation form

[jesusbalderramawgu]

Description

There's a bug with Numerical Input Component which Incorrectly Handles Formulas as numericalresponse.
after some research and talking with the community we agreed to validate the author block form to just accept numeric values in the answers.

this is how the form will show the error if the value is not numeric.

it closes [#1680]

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[diana-villalvazo-wgu]

Suggestion: In the description of the PR you can add Fixes #{PR number} or Closes #{PR number} so when this PR is merged the Github issue will be closed automatically

[jacobo-dominguez-wgu]

You need to follow the conventional commits messages

[bradenmacdonald]

Thanks! Let me know once the other reviewers have approved it, or if you need me to approve some more test runs.

[kdmccormick]

Thanks for your work so far @jesusbalderramawgu !

[kdmccormick]

The example formula provided in the "Select Problem Type" modal (m*c^2) is not valid for numeric input:

Here is a valid formula I typed into a numeric problem, and then took a screenshot of:

Unfortunately, it's not visually consistent with the rest of the example problem images in the modal. I'll reach out to see if we can get our hands on the original images... ( @marcotuts , any chance you have access to them?). In the meantime, feel free to use my screenshot, even if it looks a little off.

[kdmccormick]

Marco's working on a new image to put here, will post it here soon~

[kdmccormick]

here you go!

(for future reference: this image and its counterparts are now in the Authoring Figma file)

[kdmccormick]

Numeric input problems can also include sin, pi, and a few other functions.

I would ask you to reference the docs (https://docs.openedx.org/en/latest/educators/references/course_development/exercise_tools/numerical_input.html), but those docs aren't entirely correct either 🤦🏻 In particular, the docs say that g is allows, but this does not work in practice.

I'll have to do some digging in the code to figure out what's really allowed; I'll circle back. In the meantime, can you try updating the regex to include pi, sqrt, sin, arcscin, cos, arccos, tan, arctan, log2, and parenthases ( ) ?

[kdmccormick]

OK, here's the function which perform the numeric evaluation: https://github.com/openedx/openedx-calc/blob/master/calc/calc.py#L239

And here's the call site: https://github.com/openedx/edx-platform/blob/f4f14a69874d5804ef33778486f7d6cab400e206/xmodule/capa/responsetypes.py#L1563

Note that both variables and unary_functions are passed in as {}.

@jesusbalderramawgu , would you or your team be able to reverse engineer this function in order to figure out exactly what is allowed in a numeric input formula?

[jesusbalderramawgu]

sure, I will check this with the team

[jesusbalderramawgu]

Hello, just to follow up on the ticket, I'm still checking because now needs more work the validation part.
After this feedback, the frontend shouldn't validate if is a valid math expression, it should be on the backend. After some review I found an endpoint to do this validation but it's really attached to django views, so I'm looking for a way of request this from react and validate the input component.
I'll keep you posted, thanks in advance!

[kdmccormick]

I was also thinking that the validation might need to happen on the backend, glad to see you came to the same conclusion.

Perhaps we need to factor out a new REST API for the validation? Curious to hear what you find.

[jesusbalderramawgu]

agree on the new rest API for this validation, but gonna check with the team first in case they know something about how to reuse it.

this is where the validation is handled inside edx platform
xmodule/capa/inputtypes.py

in this function, line 1277
def preview_formcalc(self, get):

it handles every formula as latex

[jesusbalderramawgu]

I have a solution, I would like your thoughts on this.
after some digging and checking with @holaontiveros
we found that is possible to request the validation endpoint in this view, but it is required to save the numeric input first.

Basically when we select "problem" in the options and the modal opens up
a block is created with this endpoint
http://studio.local.openedx.io:8001/xblock/
returning a blockId which is required to validate the formula, but the input is not created because is not saved yet.
so we can't validate the formula without the creation of the input because even though we have a blockId it is like a temporary id until we create the input. We need to save the input first to get a valid id and be able to validate.

my proposal is to save an empty response (numerical input) when the modal opens up, that way we would have a valid id as reference and when the user types in the answer we can validate successfully.

[kdmccormick]

hey @jesusbalderramawgu , thanks for looking into this. That particular approach is not viable, because we need the editor to be able to work without saving the Problem first. You can see the importance of this by going into Libraries (Beta), creating a Problem, and hitting "Cancel" instead of saving: notice that no Problem is created.

(In Courses, on the other hand, if you being creating a Problem and hit "Cancel", you will end up with a blank problem which you have to then delete. This is an undesirable legacy behavior which we'll want to fix one day.)

I think we'll need a new endpoint, maybe one that just takes an answer string and validates it for a particular response type (formula, numeric, etc.)?

[jesusbalderramawgu]

thanks for your feedback @kdmccormick, I checked what you said about the flow and I agree.
a new endpoint is required for this then, it should receive a string and return a boolean to know if is valid or not.
do you know who can help with the creation of this endpoint?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.83%. Comparing base (36c9eba) to head (14d2c72).
⚠️ Report is 21 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2615      +/-   ##
==========================================
+ Coverage   94.81%   94.83%   +0.02%     
==========================================
  Files        1225     1234       +9     
  Lines       27481    27771     +290     
  Branches     6187     6267      +80     
==========================================
+ Hits        26056    26338     +282     
+ Misses       1367     1362       -5     
- Partials       58       71      +13     

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[jesusbalderramawgu]

You need to follow the conventional commits messages

thanks, I made the change in the current commit messages and I'll keep this in mind for future PR