ARCHITECTURE - zbycz/osmapp GitHub Wiki

Clicking POIs in map

When clicking a feature on map (useOnMapClicked), we only get skeleton. That is a feature without tags, only with a few properties computed by our MVT tiles provider. We get name, class and subclass.

Note: class and subclass is used to display icons on the map, and osmapp mirrors this behaviour in getPoiClass() so we can generally show the same icons as the webgl map.

After user clicks a POI on the map, the skeleton is shown immediately in FeaturePanel and loading indicator starts spinning.

Map feature	Skeleton
can be seen in the console	can be seen in universal debugging object called d or dbg

Fetching features

This is done by next.js extension getIntitialProps on the App component. It is run on server-side if correct URL is loaded (SSR), or later in the browser.

1. getInitialFeature() – special getCoordsFeature() can be dispatched for coordinates feature like https://osmapp.org/50.0,14.0
2. fetchFeature() - gets the data
3. fetchFeatureWithCenter()
   • for ways and relations:
     • on SSR: we ask overpass to fill in the center prop
     • in browser: we just get the center from featureCenterCache where it was saved before in useOnMapClicked. This way we save the overpass API calls for better performance.
   • osm data is converted to osmapp Feature type by osmToFeature() – compatible with GeoJSON spec
   • addSchemaToFeature() adds the iD presets and fields (we also fetch fresh fetchSchemaTranslations()). iD schema is still experimental, if this fails, osmapp will show just tags.
4. addMembersAndParents() – currently switched on only for select features