🔨 (grapher) let chart configs inherit default values / TAS-565

[sophiamersmann]

Summary

Implements chart config inheritance and makes all chart configs inherit values from a parent config with default values.

Details

• For all standalone charts, the full config is the patch config merged with the default layer
  • Whenever we save a new chart or update the existing one, we first compute the patch config by diffing against the parent/default config and then compute the full config by merging the patch with the parent
  • We usually operate on the full config, but we're baking the full config without defaults so that we're not baking the defaults again and again and again (makes a difference on explorer pages where we potentially bake tens/hundreds of configs)
  • We use the full patch config for version history. The way we currently do revisions doesn't always work¹. Using the full config for version history fixes this, but has the disadvantage that "old" default values (that have since been updated) are copied over when a config is restored.
• The default grapher config is derived from the schema and lives in the codebase. It can be generated by running the generate-default-object-from-schema.ts with the --save-ts flag
  • Whenever Grapher defaults are updated, the default config should be regenerated, and all full configs of stand-alone charts should be recomputed
  • We could have also stored the default layer in the database, but it's convenient to have it at hand in the codebase (where it's also type-checked). If some external entity needs the default config, they can access https://files.ourworldindata.org/schemas/grapher-schema.default.latest.json
• Two new functions operate on chart configs and implement inheritance:
  • mergeGrapherConfigs: merges two or more patch configs
    • Some keys are excluded from inheritance ($schema, id, slug, version, isPublished)
    • Configs with different schema versions can't be merged
  • diffGrapherConfigs: diffs a given config against some reference config, where only values that are different in both configs are kept

Caveats

• I left the chart revisions as is but now store the full config in the chart revisions table whenever a chart is saved – this could be a bit confusing
• As I said above, storing the full config in version history comes at the cost of copying over old default values when a chart is restored – how big of a problem is that?

SVG tester

I dumped two new set of configs and reference charts for the SVG tester:

• Patch configs
  • The config changes are due to diffing against the default layer (meaning, default values are removed)
  • There is one chart that is rendered differently, but it seems to be unrelated to the changes in this PR.
• Full configs
  • Few charts are added and removed, probably because I refreshed the database in between
  • Other than that, no changes

To do

• Add some real-world tests it's ok as is
• Add a GitHub workflow that re-generates the default config and checks if the diff is clean
• Delete DEFAULT_GRAPHER_CONFIG_SCHEMA

Footnotes

1. When restoring a config from version history, we re-apply an old config version. But that doesn't take default values into account. For example, let's say the v1 version of a chart relies on the default value for hasMapTab and has thus no map tab. In v2, a map tab is added (the config now contains {..., hasMapTab: true}. Restoring v1 doesn't switch hasMapTab back to false since hasMapTab isn't contained in the v1 version of the config (since we were relying on the default). ↩

[sophiamersmann]

• 🔨 (grapher) let chart configs inherit default values / TAS-565 #3782 : 2 dependent PRs (#3793 , #3890 ) 👈
• 🔨 (db) add chart_configs table / TAS-563 #3767 : 1 other dependent PR (#3743 )
• 🔨 Add wrangler.toml file #3846
• master

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[owidbot]

Quick links (staging server):

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Login: ssh owid@staging-site-inherit-defaults

• Site-screenshots: https://github.com/owid/site-screenshots/compare/inherit-defaults
• SVG tester: https://github.com/owid/owid-grapher-svgs/compare/inherit-defaults

SVG tester:

Number of differences (default views): 0 ✅
Number of differences (all views): 0 ✅

Edited: 2024-08-09 16:04:41 UTC
Execution time: 1.23 seconds

[notion-workspace]

Let charts inherit default values

[danyx23]

Nice work!

[sophiamersmann]

Merge activity

• Sep 3, 9:01 AM EDT: @sophiamersmann started a stack merge that includes this pull request via Graphite.
• Sep 3, 9:01 AM EDT: @sophiamersmann merged this pull request with Graphite.