Page history broken during navigation

[tsibley]

There's some weird behaviour with Auspice modifying page history such that the back button breaks. For example, go to https://nextstrain.org/staging, observe you get a list of staging datasets and no 404 message, click a dataset, click the back button. You end up with a 404 message and a list of "live" datasets, instead of where you were (but the URL is intact). This manifests with other pages as well. I suspect this is because Auspice is being too greedy about what it considers a dataset for display.

Discussion about this started here: https://bedfordlab.slack.com/archives/C116R9PR7/p1568322725029100

[joverlee521]

I won't have time this week to work on this issue, but I did do some digging and wanted to document here for future reference (for myself or anyone else who wants to work on this):

1. An event listener monitors for popstate event in /src/components/framework/monitor.js
2. A popstate event would trigger the changePage action in /src/actions/navigation.js
3. If the path has changed, then dispatch with:
   • action.type : PAGE_CHANGE
   • action.displayComponent : "datasetLoader"
4. This goes to the general reducer in src/reducers/general.js to create a new state for displayComponent
5. Changes to the displayComponent state leads to re-render of MainComponentSwitch in /src/root.js and returns the DatasetLoader in /src/components/datasetLoader/index.js
6. The DatasetLoader triggers the loadJSONs action in /src/actions/loadData.js, which calls fetchDataAndDispatch
7. fetchDataAndDispatch calls getDataset(mainDatasetUrl) which is where the app actually reaches an error:

Trace: Error:  not in available datasets
    at Object.extendDataPathsToMatchAvailable (/Users/jlee2346/Repos/nextstrain/auspice/cli/server/getDatasetHelpers.js:59:11)
    at /Users/jlee2346/Repos/nextstrain/auspice/cli/server/getDataset.js:9:15
    at Console.trace (internal/console/constructor.js:336:11)
    at /Users/jlee2346/Repos/nextstrain/auspice/cli/server/getDataset.js:13:15
[warning]       couldn't fetch JSONs --  not in available datasets

After writing all that out, I'm also not entirely sure in which step should changes be made to ensure that auspice is not being "too greedy"

I guess github is my rubber duck today. See PR #841.