topic Uncaught TypeError: Cannot read properties of null (reading '0') in ArcGIS JavaScript Maps SDK Questions

Uncaught TypeError: Cannot read properties of null (reading '0')

siefaqel — Sun, 16 Jul 2023 11:48:43 GMT

I am trying to query features from the feature layer view and add these features to a graphics layer to enable snapping on the features using the sketch view model I already have, but on a large scale, i start to see this error: " Uncaught TypeError: Cannot read properties of null (reading '0') ".

NOTE: when I comment : " gfxLayer.add(g) " or " new FeatureSnappingLayerSource({ layer: gfxLayer as __esri.GraphicsLayer,

enabled: true,

}), " or " visible: false," I don't see the error anymore, but snapping does not work.

any thoughts?

sketchVmRef.current = new SketchViewModel({ view: mapView, layer: new GraphicsLayer({}), snappingOptions: { enabled: true, featureSources: [ new FeatureSnappingLayerSource({ layer: gfxLayer as __esri.GraphicsLayer, enabled: true, }), ], }, }) const queriedFeatures = await featureLayerView.queryFeatures({ where: `1=1`, outFields: ['*'], returnGeometry: true, }) for (const feature of queriedFeatures.features) { const g = new Graphic({ geometry: feature.geometry, attributes: feature.attributes, layer: gfxLayer, // visible: false, }) gfxLayer.add(g) }

Re: Uncaught TypeError: Cannot read properties of null (reading '0')

UndralBatsukh — Mon, 17 Jul 2023 19:32:16 GMT

Hi there,

I am not able to reproduce the behavior you describe. Would you mind creating a simple reproducible case? You can use this codepen as starting point: https://codepen.io/U_B_U/pen/BaGxBqK?editors=100

Re: Uncaught TypeError: Cannot read properties of null (reading '0')

JoelBennett — Wed, 19 Jul 2023 22:56:37 GMT

The error appears to be driven by your implementation of "gfxLayer". Can you provide more code as it relates to that object (i.e. its construction, setting of properties, etc)?

I encountered this same error message yesterday, although it's unlikely we had the same problem. The error message occurs when an Array is expected, but a value of null is received. In my case, I was trying to use a UniqueValueRenderer created from JSON with the uniqueValueGroups specified. The JSON structure for uniqueValueGroups differs from the autocast structure, and is still undocumented, but I fumbled my way through it.