在angular 2中更新ng-charts条形图数据集 [英] Updating ng-charts barchart datasets in angular 2

问题描述

如何从angular2更新条形图？我试图将新条目添加到 [datasets] = barChartData
模板中，图形如下所示：

How to update barchart from angular2? I am trying to add new entry on click to [datasets]="barChartData" In template, graph looks like this:

<canvas baseChart #myChart
[datasets]="barChartData"
[labels]="barChartLabels"
[options]="barChartOptions"
[legend]="barChartLegend"
[chartType]="barChartType"
(chartHover)="chartHovered($event)"
(chartClick)="chartClicked($event)"></canvas>

我尝试了以下推荐方法：
1）直接更改数据集变量-克隆了数据，更改它，然后分配它。这样，我可以更改/更新现有数据，但不能将新条目添加到数据集。

I tried following recommended methods: 1) Changed dataset variable directly - cloned the data , changed it and then assigned it. This way I can change/update exsiting data but I can't add new entry to dataset.

2）ChangeDetectorRef，我向构造函数添加了私有引用：ChangeDetectorRef，并称为 ref.detectChanges（）进行更新。但没有运气。我也尝试过使用ApplicationRef。

2) ChangeDetectorRef, I added private ref: ChangeDetectorRef to constructor and called ref.detectChanges() on updates. but no luck. I also tried using ApplicationRef.

在两种情况下，在调试窗口中，我都可以看到ts文件中的barChartData已更新为新值，而template（html）却没有

In both cases, in debug window, I can see that barChartData is updated with new values in ts file, but template(html) is not updated/refreshed.

推荐答案

经过一天的痛苦，我找到了一个可行的解决方案：
首先您必须导入指令：

After one day of agony I found a working solution: first you have to import directive:

import {BaseChartDirective} from 'ng2-charts/ng2-charts'

然后在课堂上参考图表：

then reference chart in class:

@ViewChild(BaseChartDirective)
public chart: BaseChartDirective;

现在，您可以在带有图表对象的模板中访问图表。然后，当您想刷新图表时，放置以下代码：

Now you can access your chart in template with chart object. Then place this code when you want to refresh your chart:

this.chart.ngOnChanges({} as SimpleChanges);

请确保您将空对象作为SimpleChanges类型传递。仅当参数为空对象时，ngOnChanges才会再次重绘图表。

Make sure that you pass empty object as type SimpleChanges. ngOnChanges will redraw chart again only if argument is empty object.

请注意，您必须在调用ngOnChanges之前克隆并更改对数据集的引用。
在我的情况下，我这样做是为了刷新图形：`

Please note that you have to clone and change referance to datasets before calling ngOnChanges. In my case I did this to refresh graph:`

this.barChartData = clone;
this.chart.datasets = this.barChartData;
this.chart.ngOnChanges({} as SimpleChanges);`

这篇关于在angular 2中更新ng-charts条形图数据集的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！