Hide scatterplot for large schools

[edavidsonsawyer]

Who is this PR for?

Educators

What problem does this PR fix?

For large schools, the scatterplot in the discipline dashboard has too many datapoints to show useful information.

What does this PR do?

Removes the scatterplot feature when there are more than 500 discipline incidents to display when first loading

Checklists

Which features or pages does this PR touch?

• Discipline

Does this PR use tests to help verify we can deploy these changes quickly and confidently?

• Included specs for changes
• Improved specs for existing code in need of better test coverage
• Manual testing made more sense here

[edavidsonsawyer]

@kevinrobinson here's the simpler version of disabling the scatter plot for large schools. I'm not sure what's up with the build error so I'll try to look into that later on today.

[kevinrobinson]

nice!

[kevinrobinson]

Can you say more about why this is here, rather than computed in render? I don't follow why it's using the lifecycle hook.

[edavidsonsawyer]

It's here because the state has to change (from default scatter to some alternative), which can't be done in render. I could probably set the initial state conditionally in the constructor, but it seemed cleaner to just use getIncidentsFromStudents in the mounted component. It shouldn't be much of a performance issue since we cache the result of that function with memoizer.

[kevinrobinson]

ah, thanks! Got it, it's because this is set in initialState in the constructor, that's super helpful. Using the lifecycle hook implies that it's because of something related to the DOM or outside of React, and then leads to double-rendering on load.

Yeah, the better way to do this is describe this explicitly in the constructor, and then let initialState decide what selectedChart should be based on those props. Here that would involve factoring out the incident and filtering functions to be plain functions (rather than relying on this.state and this.props) and that seems a larger change than this is worth.

So if you tested this and it works without a visible jump, let me know and let's 🚢 as is. And thanks for explaining and helping me learn! 👍

[edavidsonsawyer]

Great! I have tested this locally with schools above and below the 500 student threshold, and in the former case the scatter plot is cleanly removed. I would like to double check in production just to be sure the threshold is appropriate, but that can probably come from feedback from users.

[kevinrobinson]

@edavidsonsawyer awesome, thanks! 🚢 ing now and I'll verify as well when it's out.

[kevinrobinson]

@edavidsonsawyer looks good! 👍 It looks like there's a separate issue with SHS, which I'd best is from the call to latest_note (since a larger MS school in New Bedford with less notes loads just fine). I'll add that to the list of things to get this functional enough for Somerville general release.