Allow a dataset to specify a different data key

Author: etimberg

docs/docs/general/data-structures.md

@@ -64,6 +64,7 @@ In this mode, property name is used for `index` scale and value for `value` scal
 
 | Name | Type | Description
 | ---- | ---- | -----------
+| `dataKey` | `string` | If specified, tells the chart to look for the dataset data in `dataset[dataset.dataKey]`. If unspecified, this defaults to `'data'`.
 | `label` | `string` | The label for the dataset which appears in the legend and tooltips.
 | `clip` | `number`\|`object` | How to clip relative to chartArea. Positive value allows overflow, negative value clips that many pixels inside chartArea. 0 = clip at chartArea. Clipping can also be configured per side: clip: {left: 5, top: false, right: -2, bottom: 0}
 | `order` | `number` | The drawing order of dataset. Also affects order for stacking, tooltip and legend.

src/controllers/controller.doughnut.js

@@ -56,7 +56,8 @@ export default class DoughnutController extends DatasetController {
 	 * Override data parsing, since we are not using scales
 	 */
 	parse(start, count) {
-		const data = this.getDataset().data;
+		const dataKey = this.getDataKey();
+		const data = this.getDataset()[dataKey];
 		const meta = this._cachedMeta;
 		let i, ilen;
 		for (i = start, ilen = start + count; i < ilen; ++i) {

src/controllers/controller.polarArea.js

@@ -52,6 +52,7 @@ export default class PolarAreaController extends DatasetController {
 		const centerX = scale.xCenter;
 		const centerY = scale.yCenter;
 		const datasetStartAngle = getStartAngleRadians(opts.startAngle);
+		const dataKey = me.getDataKey();
 		let angle = datasetStartAngle;
 		let i;
 
@@ -64,7 +65,7 @@ export default class PolarAreaController extends DatasetController {
 			const arc = arcs[i];
 			let startAngle = angle;
 			let endAngle = angle + me._computeAngle(i, mode);
-			let outerRadius = this.chart.getDataVisibility(i) ? scale.getDistanceFromCenterForValue(dataset.data[i]) : 0;
+			let outerRadius = this.chart.getDataVisibility(i) ? scale.getDistanceFromCenterForValue(dataset[dataKey][i]) : 0;
 			angle = endAngle;
 
 			if (reset) {
@@ -94,10 +95,11 @@ export default class PolarAreaController extends DatasetController {
 	countVisibleElements() {
 		const dataset = this.getDataset();
 		const meta = this._cachedMeta;
+		const dataKey = this.getDataKey();
 		let count = 0;
 
 		meta.data.forEach((element, index) => {
-			if (!isNaN(dataset.data[index]) && this.chart.getDataVisibility(index)) {
+			if (!isNaN(dataset[dataKey][index]) && this.chart.getDataVisibility(index)) {
 				count++;
 			}
 		});
@@ -113,8 +115,9 @@ export default class PolarAreaController extends DatasetController {
 		const meta = me._cachedMeta;
 		const count = meta.count;
 		const dataset = me.getDataset();
+		const dataKey = me.getDataKey();
 
-		if (isNaN(dataset.data[index]) || !this.chart.getDataVisibility(index)) {
+		if (isNaN(dataset[dataKey][index]) || !this.chart.getDataVisibility(index)) {
 			return 0;
 		}
 

src/controllers/controller.radar.js

@@ -44,13 +44,14 @@ export default class RadarController extends DatasetController {
 	updateElements(points, start, count, mode) {
 		const me = this;
 		const dataset = me.getDataset();
+		const dataKey = me.getDataKey();
 		const scale = me._cachedMeta.rScale;
 		const reset = mode === 'reset';
 
 		for (let i = start; i < start + count; i++) {
 			const point = points[i];
 			const options = me.resolveDataElementOptions(i, mode);
-			const pointPosition = scale.getPointPositionForValue(i, dataset.data[i]);
+			const pointPosition = scale.getPointPositionForValue(i, dataset[dataKey][i]);
 
 			const x = reset ? scale.xCenter : pointPosition.x;
 			const y = reset ? scale.yCenter : pointPosition.y;

src/core/core.datasetController.js

@@ -1,6 +1,6 @@
 import Animations from './core.animations';
 import defaults from './core.defaults';
-import {isObject, merge, _merger, isArray, valueOrDefault, mergeIf, resolveObjectKey, _capitalize} from '../helpers/helpers.core';
+import {isObject, merge, _merger, isArray, valueOrDefault, mergeIf, resolveObjectKey, _capitalize, isNullOrUndef} from '../helpers/helpers.core';
 import {listenArrayEvents, unlistenArrayEvents} from '../helpers/helpers.collection';
 import {resolve} from '../helpers/helpers.options';
 import {getHoverColor} from '../helpers/helpers.color';
@@ -275,6 +275,11 @@ export default class DatasetController {
 		return this.chart.data.datasets[this.index];
 	}
 
+	getDataKey() {
+		const {dataKey} = this.getDataset();
+		return isNullOrUndef(dataKey) ? 'data' : dataKey;
+	}
+
 	getMeta() {
 		return this.chart.getDatasetMeta(this.index);
 	}
@@ -320,7 +325,8 @@ export default class DatasetController {
 	_dataCheck() {
 		const me = this;
 		const dataset = me.getDataset();
-		const data = dataset.data || (dataset.data = []);
+		const dataKey = me.getDataKey();
+		const data = dataset[dataKey] || (dataset[dataKey] = []);
 
 		// In order to correctly handle data addition/deletion animation (an thus simulate
 		// real-time charts), we need to monitor these data modifications and synchronize
@@ -386,6 +392,7 @@ export default class DatasetController {
 	 */
 	configure() {
 		const me = this;
+		const dataKey = me.getDataKey();
 		me._config = merge(Object.create(null), [
 			defaults.controllers[me._type].datasets,
 			(me.chart.options.datasets || {})[me._type],
@@ -395,7 +402,7 @@ export default class DatasetController {
 				// Cloning the data is expensive and unnecessary.
 				// Additionally, plugins may add dataset level fields that should
 				// not be cloned. We identify those via an underscore prefix
-				if (key !== 'data' && key.charAt(0) !== '_') {
+				if (key !== 'data' && key !== dataKey && key.charAt(0) !== '_') {
 					_merger(key, target, source);
 				}
 			}
@@ -1023,7 +1030,8 @@ export default class DatasetController {
 	 */
 	_onDataPush() {
 		const count = arguments.length;
-		this._insertElements(this.getDataset().data.length - count, count);
+		const dataKey = this.getDataKey();
+		this._insertElements(this.getDataset()[dataKey].length - count, count);
 	}
 
 	/**

types/index.esm.d.ts

@@ -527,7 +527,8 @@ export class DatasetController<TElement extends Element = Element, TDatasetEleme
 	protected getMaxOverflow(): boolean | number;
 	draw(): void;
 	reset(): void;
-	getDataset(): ChartDataset;
+  getDataset(): ChartDataset;
+  getDataKey(): string;
 	getMeta(): ChartMeta<TElement, TDatasetElement>;
 	getScaleForId(scaleID: string): Scale | undefined;
 	configure(): void;