feat: datasetIdKey prop (#848)

datasetIdKey prop added to track datasets changes

Author: dangreen

Diff for: .size-limit

@@ -1,7 +1,7 @@
 [
   {
     "path": "dist/index.cjs",
-    "limit": "1.6 KB",
+    "limit": "1.7 KB",
     "webpack": false,
     "running": false
   },

Diff for: src/chart.tsx

@@ -21,6 +21,7 @@ function ChartComponent<
     height = 150,
     width = 300,
     redraw = false,
+    datasetIdKey,
     type,
     data,
     options,
@@ -40,7 +41,7 @@ function ChartComponent<
 
     chartRef.current = new ChartJS(canvasRef.current, {
       type,
-      data: cloneData(data),
+      data: cloneData(data, datasetIdKey),
       options,
       plugins,
     });
@@ -71,7 +72,7 @@ function ChartComponent<
 
   useEffect(() => {
     if (!redraw && chartRef.current && data.datasets) {
-      setDatasets(chartRef.current.config.data, data.datasets);
+      setDatasets(chartRef.current.config.data, data.datasets, datasetIdKey);
     }
   }, [redraw, data.datasets]);
 

Diff for: src/types.ts

@@ -18,6 +18,7 @@ export interface ChartProps<
   options?: ChartOptions<TType>;
   plugins?: Plugin<TType>[];
   redraw?: boolean;
+  datasetIdKey?: string;
   /**
    * @todo Replace with `children` prop.
    */

Diff for: src/utils.ts

@@ -8,6 +8,8 @@ import type {
   Chart,
 } from 'chart.js';
 
+const defaultDatasetIdKey = 'label';
+
 export function reforwardRef<T>(ref: ForwardedRef<T>, value: T) {
   if (typeof ref === 'function') {
     ref(value);
@@ -41,17 +43,27 @@ export function setDatasets<
   TLabel = unknown
 >(
   currentData: ChartData<TType, TData, TLabel>,
-  nextDatasets: ChartDataset<TType, TData>[]
+  nextDatasets: ChartDataset<TType, TData>[],
+  datasetIdKey = defaultDatasetIdKey
 ) {
+  const addedDatasets: ChartDataset<TType, TData>[] = [];
+
   currentData.datasets = nextDatasets.map(nextDataset => {
     // given the new set, find it's current match
     const currentDataset = currentData.datasets.find(
-      dataset =>
-        dataset.label === nextDataset.label && dataset.type === nextDataset.type
+      dataset => dataset[datasetIdKey] === nextDataset[datasetIdKey]
     );
 
     // There is no original to update, so simply add new one
-    if (!currentDataset || !nextDataset.data) return { ...nextDataset };
+    if (
+      !currentDataset ||
+      !nextDataset.data ||
+      addedDatasets.includes(currentDataset)
+    ) {
+      return { ...nextDataset };
+    }
+
+    addedDatasets.push(currentDataset);
 
     Object.assign(currentDataset, nextDataset);
 
@@ -63,14 +75,14 @@ export function cloneData<
   TType extends ChartType = ChartType,
   TData = DefaultDataPoint<TType>,
   TLabel = unknown
->(data: ChartData<TType, TData, TLabel>) {
+>(data: ChartData<TType, TData, TLabel>, datasetIdKey = defaultDatasetIdKey) {
   const nextData: ChartData<TType, TData, TLabel> = {
     labels: [],
     datasets: [],
   };
 
   setLabels(nextData, data.labels);
-  setDatasets(nextData, data.datasets);
+  setDatasets(nextData, data.datasets, datasetIdKey);
 
   return nextData;
 }

Diff for: test/chart.test.tsx

@@ -324,4 +324,66 @@ describe('<Chart />', () => {
 
     expect(chart.canvas.getAttribute('aria-label')).toBe(ariaLabel);
   });
+
+  it('should rerender datasets with same labels', () => {
+    const getData = () => ({
+      labels: [1, 2, 3],
+      datasets: [
+        {
+          label: '',
+          data: [5, 6, 7],
+        },
+        {
+          label: '',
+          data: [3, 2, 1],
+        },
+      ],
+    });
+
+    const { rerender } = render(
+      <Chart ref={ref} type='line' data={getData()} />
+    );
+
+    const [prevDataset1, prevDataset2] = chart.config.data.datasets;
+
+    rerender(<Chart ref={ref} type='line' data={getData()} />);
+
+    const [nextDataset1, nextDataset2] = chart.config.data.datasets;
+
+    expect(prevDataset1).toBe(nextDataset1);
+    expect(prevDataset2).not.toBe(nextDataset2);
+  });
+
+  it('should rerender datasets with id', () => {
+    const getData = () => ({
+      labels: [1, 2, 3],
+      datasets: [
+        {
+          id: 1,
+          label: '',
+          data: [5, 6, 7],
+        },
+        {
+          id: 2,
+          label: '',
+          data: [3, 2, 1],
+        },
+      ],
+    });
+
+    const { rerender } = render(
+      <Chart ref={ref} datasetIdKey='id' type='line' data={getData()} />
+    );
+
+    const [prevDataset1, prevDataset2] = chart.config.data.datasets;
+
+    rerender(
+      <Chart ref={ref} datasetIdKey='id' type='line' data={getData()} />
+    );
+
+    const [nextDataset1, nextDataset2] = chart.config.data.datasets;
+
+    expect(prevDataset1).toBe(nextDataset1);
+    expect(prevDataset2).toBe(nextDataset2);
+  });
 });