Typescript: common function to get dataset ?

[sloonz]

Hello,

I’m trying to make a common function that would return the same dataset for a pie or a chart. Typescript seems to complain, and I’m not sure why :

import {ChartDataset} from "chart.js";

function getDataSets<T extends "pie" | "bar">(): ChartDataset<T>[] {
    return [{label: "Dataset 1", data: [1, 2, 1]}, {label: "Dataset 2", data: [2, 1, 2]}];
}

Type '{ label: string; data: (1 | 2)[]; }' is not assignable to type 'ChartDataset<T, DistributiveArray<ChartTypeRegistry[T]["defaultDataPoint"]>>'.
  Type '{ label: string; data: (1 | 2)[]; }' is not assignable to type 'DeepPartial<{ pie: { type: "pie"; } & DoughnutControllerDatasetOptions; bar: { type: "bar"; } & BarControllerDatasetOptions; ... 5 more ...; radar: { ...; } & ... 1 more ... & FillerControllerDatasetOptions; }[T]>'.
Type '{ label: string; data: (1 | 2)[]; }' is not assignable to type 'ChartDataset<T, DistributiveArray<ChartTypeRegistry[T]["defaultDataPoint"]>>'.
  Type '{ label: string; data: (1 | 2)[]; }' is not assignable to type 'DeepPartial<{ pie: { type: "pie"; } & DoughnutControllerDatasetOptions; bar: { type: "bar"; } & BarControllerDatasetOptions; ... 5 more ...; radar: { ...; } & ... 1 more ... & FillerControllerDatasetOptions; }[T]>'.

Any idea on how to do that without cheating (aka using as any) ? I tried that, which is already kinda inferior, but with the same error as a result :

import {ChartDataset} from "chart.js";

function getDataSets<T extends "pie" | "bar">(type: T): ChartDataset<T>[] {
    return [{type, label: "Dataset 1", data: [1, 2, 1]}, {type, label: "Dataset 2", data: [2, 1, 2]}];
}