fix: update 'No data' handling

src/controls/controlsLocale.js

@@ -1,7 +1,7 @@
 const controlsLocale = {
     'SearchControl.SearchForPlace': 'Search for place or address',
     'FitBoundsControl.ZoomToContent': 'Zoom to content',
-    'HoverLabel.NoData': 'No data',
+    'Label.NoData': 'No data',
     'MeasureControl.MeasureDistancesAndAreas': 'Measure distances and areas',
     'MeasureControl.ClickStartMeasurement':
         'Click where you want to start the measurement',

src/layers/Layer.js

@@ -1,9 +1,9 @@
-import { v4 as uuid } from 'uuid'
 import bbox from '@turf/bbox'
 import { Evented } from 'maplibre-gl'
-import { addImages } from '../utils/images'
-import { featureCollection } from '../utils/geometry'
+import { v4 as uuid } from 'uuid'
 import { bufferSource } from '../utils/buffers'
+import { featureCollection } from '../utils/geometry'
+import { addImages } from '../utils/images'
 import { labelSource } from '../utils/labels'
 import { setLayersOpacity } from '../utils/opacity'
 
@@ -346,8 +346,8 @@ class Layer extends Evented {
             const content = (hoverLabel || label).replace(
                 /\{ *([\w_-]+) *\}/g,
                 (str, key) =>
-                    properties[key] ||
-                    (key === 'value' ? this.locale('HoverLabel.NoData') : '')
+                    properties[key] ??
+                    (key === 'value' ? this.locale('Label.NoData') : '')
             )
 
             this._map.showLabel(content, evt.lngLat)

src/utils/__tests__/labels.spec.js

@@ -1,10 +1,133 @@
-import { labelLayer } from '../labels'
+import { labelSource, labelLayer } from '../labels'
 import defaults from '../style'
 
 const id = 'abc'
 const opacity = 0.5
+const fontSize = 10
+const labelNoData = 'No Data'
+const isBoundary = false
+const geometryPoint = {
+    type: 'Point',
+    coordinates: [0, 0],
+}
+const features = [
+    {
+        // Test a polygon
+        geometry: {
+            type: 'Polygon',
+            coordinates: [
+                [
+                    [0, 0],
+                    [1, 0],
+                    [1, 1],
+                    [0, 1],
+                    [0, 0],
+                ],
+            ],
+        },
+        properties: {
+            name: 'Feature1',
+            radius: 1,
+            value: 1,
+        },
+    },
+    {
+        // Test a point with a valid value which is not 0
+        geometry: geometryPoint,
+        properties: {
+            name: 'Feature2',
+            radius: 1,
+            value: 1,
+        },
+    },
+    {
+        // Test a point with a valid value which is 0
+        geometry: geometryPoint,
+        properties: {
+            name: 'Feature3',
+            radius: 1,
+            value: 0,
+        },
+    },
+    {
+        // Test a point with no value
+        geometry: geometryPoint,
+        properties: {
+            name: 'Feature4',
+            radius: 1,
+        },
+    },
+]
+const generateLabelSourceItem = (coordinates, name, anchor, offset, value) => {
+    return {
+        type: 'Feature',
+        geometry: {
+            type: 'Point',
+            coordinates,
+        },
+        properties: {
+            name,
+            anchor,
+            offset,
+            color: '#333',
+            value,
+        },
+    }
+}
 
 describe('labels', () => {
+    it('Handles different label sources scenario', () => {
+        const expected = {
+            type: 'geojson',
+            data: {
+                type: 'FeatureCollection',
+                features: [
+                    // Label for a polygon
+                    generateLabelSourceItem(
+                        [0.5, 0.5],
+                        'Feature1',
+                        'center',
+                        [0, 0],
+                        1
+                    ),
+                    // Label for a point with a valid value which is not 0
+                    generateLabelSourceItem(
+                        [0, 0],
+                        'Feature2',
+                        'top',
+                        [0, 0.5],
+                        1
+                    ),
+                    // Label for a point with a valid value which is 0
+                    generateLabelSourceItem(
+                        [0, 0],
+                        'Feature3',
+                        'top',
+                        [0, 0.5],
+                        0
+                    ),
+                    // Label for a point with no value
+                    generateLabelSourceItem(
+                        [0, 0],
+                        'Feature4',
+                        'top',
+                        [0, 0.5],
+                        'No Data'
+                    ),
+                ],
+            },
+        }
+        const received = labelSource(
+            features,
+            { fontSize, labelNoData },
+            isBoundary
+        )
+
+        expect(JSON.stringify(received, null, 2)).toEqual(
+            JSON.stringify(expected, null, 2)
+        )
+    })
+
     it('Should set opacity for for label layer', () => {
         expect(labelLayer({ id, opacity }).paint['text-opacity']).toBe(opacity)
     })

src/utils/labels.js

@@ -15,7 +15,11 @@ const fonts = {
 const getOffsetEms = (type, radius = 5, fontSize = 11) =>
     type === 'Point' ? radius / parseInt(fontSize, 10) + 0.4 : 0
 
-export const labelSource = (features, { fontSize }, isBoundary) => ({
+export const labelSource = (
+    features,
+    { fontSize, labelNoData = '' },
+    isBoundary
+) => ({
     type: 'geojson',
     data: featureCollection(
         features.map(({ geometry, properties }) => ({
@@ -32,7 +36,7 @@ export const labelSource = (features, { fontSize }, isBoundary) => ({
                     getOffsetEms(geometry.type, properties.radius, fontSize),
                 ],
                 color: isBoundary ? properties.color : '#333',
-                value: properties.value,
+                value: properties.value ?? labelNoData,
             },
         }))
     ),