I have a map that relates to a table. When the user selects a table row, I would like to highlight the corresponding map feature. This is the only way I found to do it:

const siteGeoJSON = SitesToGeoJSON(sites, activeId);
const newSource = new carto.source.GeoJSON(siteGeoJSON);
siteLayer.update(newSource, siteViz);

What I'm doing here is regenerating the entire GeoJSON object to set a single property indicating whether each feature is active or not, then digesting that into Carto anew. Features with the active property have a different symbol.

This probably isn't a very efficient way to do this, though. Is there any way to change feature properties without creating a new source?

  • This doesn't directly answer this question, but it solved the problem. Instead of changing the property, I found a way to change the presentation: I hold on to siteViz then iterate through the features contained in siteViz.variables.visibleFeatures.value to find the site I want to change, and enlarge it by using f.width.blendTo(16, 200) and later f.width.reset(). – ed94133 Sep 17 '19 at 18:48
  • If it works, I would say it is a valid answer. So I would suggest posting your answer in more detail and more code snippets (or link to working example). – ramiroaznar Sep 18 '19 at 7:51

I solved this by holding onto siteViz as an upper-scope Javascript variable, initializing it with this: @visibleFeatures: viewportFeatures($id)

When the user hovers on a table row, I use State in React to set an activeId, and a corresponding side-effect function (useEffect) updates the map:

    siteViz.variables.visibleFeatures.value.forEach(f => {
      if (f.properties.id === activeId) {
        f.width.blendTo(16, 200);
      } else {
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