Add support for custom data structure (#75)

* Add support for custom data structure

* Use proper array for length

Author: kurkle

README.md

@@ -94,6 +94,37 @@ const chart = new Chart(ctx, {
 });
 ```
 
+### Custom data structure
+
+Custom data structure can be used by specifying the custom data keys in `options.parsing`.
+For example:
+
+```js
+const chart = new Chart(ctx, {
+  type: 'sankey',
+  data: {
+    datasets: [
+      {
+        data: [
+          {source: 'a', destination: 'b', value: 20},
+          {source: 'c', destination: 'd', value: 10},
+          {source: 'c', destination: 'e', value: 5},
+        ],
+        colorFrom: 'red',
+        colorTo: 'green'
+      }
+    ]
+  },
+  options: {
+    parsing: {
+      from: 'source',
+      to: 'destination',
+      flow: 'value'
+    }
+  }
+});
+```
+
 ## Example
 
 ![Sankey Example Image](sankey.png)

src/controller.js

@@ -81,9 +81,11 @@ export default class SankeyController extends DatasetController {
    * @return {Array<SankeyParsedData>}
    */
   parseObjectData(meta, data, start, count) {
+    const {from: fromKey = 'from', to: toKey = 'to', flow: flowKey = 'flow'} = this.options.parsing;
+    const sankeyData = data.map(({[fromKey]: from, [toKey]: to, [flowKey]: flow}) => ({from, to, flow}));
     const {xScale, yScale} = meta;
     const parsed = []; /* Array<SankeyParsedData> */
-    const nodes = this._nodes = buildNodesFromRawData(data);
+    const nodes = this._nodes = buildNodesFromRawData(sankeyData);
     /* getDataset() => SankeyControllerDatasetOptions */
     const {column, priority, size} = this.getDataset();
     if (priority) {
@@ -102,13 +104,13 @@ export default class SankeyController extends DatasetController {
       }
     }
 
-    const {maxX, maxY} = layout(nodes, data, !!priority, validateSizeValue(size));
+    const {maxX, maxY} = layout(nodes, sankeyData, !!priority, validateSizeValue(size));
 
     this._maxX = maxX;
     this._maxY = maxY;
 
-    for (let i = 0, ilen = data.length; i < ilen; ++i) {
-      const dataPoint = data[i];
+    for (let i = 0, ilen = sankeyData.length; i < ilen; ++i) {
+      const dataPoint = sankeyData[i];
       const from = nodes.get(dataPoint.from);
       const to = nodes.get(dataPoint.to);
       const fromY = from.y + getAddY(from.to, dataPoint.to, i);

test/fixtures/parsing.js

@@ -0,0 +1,31 @@
+module.exports = {
+  config: {
+    type: 'sankey',
+    data: {
+      datasets: [
+        {
+          data: [
+            {source: 'a', destination: 'b', value: 20},
+            {source: 'c', destination: 'd', value: 10},
+            {source: 'c', destination: 'e', value: 5},
+          ],
+          colorFrom: 'red',
+          colorTo: 'green'
+        }
+      ]
+    },
+    options: {
+      parsing: {
+        from: 'source',
+        to: 'destination',
+        flow: 'value'
+      }
+    }
+  },
+  options: {
+    canvas: {
+      height: 256,
+      width: 512
+    }
+  }
+};