问题
I am starting to work these days with Angular2, and have a question with the framework ng2-charts.
Here is my component.ts code :
import { Component } from '@angular/core';
import { ChartsModule } from 'ng2-charts';
import { PredictionService } from './prediction.service'
@Component({
selector: 'prediction-result-chart',
templateUrl: './predictionResultChart.component.html'
})
export class PredictionResultChartComponent{
public pieChartLabels:string[] = [];
public pieChartData:number[] = [];
public pieChartType:string = 'pie';
public JSONobject = {}
constructor(private predictionService: PredictionService){
this.getPredictions();
}
public getPredictions() {
this.predictionService.getPredictions('hello').do(result => this.populateChart(result)).subscribe();
}
public populateChart(obj): void{
let labels:string[] = [];
let data:number[] = [];
for (var i = 0; i < obj.predictions.length; i++)
{
labels.push(String(obj.predictions[i].class));
data.push(obj.predictions[i].percentage);
};
this.pieChartData = data;
this.pieChartLabels = labels;
}
public chartClicked(e:any):void {}
public chartHovered(e:any):void {}
}
The component.html code :
<div style="display: block">
<canvas baseChart
[data]="pieChartData"
[labels]="pieChartLabels"
[chartType]="pieChartType"
(chartHover)="chartHovered($event)"
(chartClick)="chartClicked($event)"></canvas>
</div>
The service code :
import { Injectable } from '@angular/core';
import { Http, Response, Headers } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
@Injectable()
export class PredictionService {
private baseUrl: string = 'http://localhost:8080/predict/';
constructor(private http : Http){
}
getPredictions(text :string) {
return this.http.get(this.baseUrl + text).map(res => res.json());
}
}
With the codes above, here is what I have, a chart without any colors :
In fact when I looked deeply into my code, the HTML component took the variables at the beginning and update them then. So when the labels are empty, even if I add some labels, they will be added as undefined. So I have a chart with the right values but not the right labels. Everything marked as undefined.
And if I initiate the labels at the beginning, I will have a good coloured chart with the right values
So my questions are :
How to load the data, then render the HTML component ?
Is there anyway to render the chart.js component with no data and update it with right labels and data ?
Any help is needed, thanks.
回答1:
In standard chart.js you can use the .update() prototype method to re-render a chart after you have modified its data (including labels).
However, it appears that ng2-charts doesn't provide a mechanism to trigger the update (as per this github issue). I'm not very experienced in Angular2 at all, but perhaps this will work for you? The approach was taken from a comment made by zbagley in the github issue posted 17 days ago (unfortunately I could not find a way to generate a url referencing this specific comment).
The approach is to basically not render your chart until the data is available. Here is the change to your component.ts code.
import { Component } from '@angular/core';
import { ChartsModule } from 'ng2-charts';
import { PredictionService } from './prediction.service'
@Component({
selector: 'prediction-result-chart',
templateUrl: './predictionResultChart.component.html'
})
export class PredictionResultChartComponent {
public pieChartLabels:string[] = [];
public pieChartData:number[] = [];
public pieChartType:string = 'pie';
public JSONobject = {};
public isDataAvailable:boolean = false;
constructor(private predictionService: PredictionService){
this.getPredictions();
}
public getPredictions() {
this.predictionService.getPredictions('hello').do(result => this.populateChart(result)).subscribe();
}
public populateChart(obj): void {
let labels:string[] = [];
let data:number[] = [];
for (var i = 0; i < obj.predictions.length; i++)
{
labels.push(String(obj.predictions[i].class));
data.push(obj.predictions[i].percentage);
};
this.pieChartData = data;
this.pieChartLabels = labels;
this.isDataAvailable = true;
}
public chartClicked(e:any):void {}
public chartHovered(e:any):void {}
}
And then you would use ngIf in your component.html code.
<div style="display: block" *ngIf="isDataAvailable">
<canvas baseChart
[data]="pieChartData"
[labels]="pieChartLabels"
[chartType]="pieChartType"
(chartHover)="chartHovered($event)"
(chartClick)="chartClicked($event)"></canvas>
</div>
回答2:
I can get the values when i print to console but does not display on the chart.
this.pieChartLabels :: ['PayDirect agent deposit','GtCollections agent deposit','Quickteller agent deposit']
this.pieChartData :: [1990,1202,2476]
Is there a way to update the chart. It seems the chart was loaded before the data was received from the web service.
isDataAvailable2 = true
but the chart never loaded.
回答3:
I updated the chart labels by updating the labels in the config property.
import { Component } from '@angular/core';
import { ChartsModule } from 'ng2-charts';
import { PredictionService } from './prediction.service'
import { BaseChartDirective } from 'ng2-charts'; // ----- added
@Component({
selector: 'prediction-result-chart',
templateUrl: './predictionResultChart.component.html'
})
export class PredictionResultChartComponent {
public pieChartLabels:string[] = [];
public pieChartData:number[] = [];
public pieChartType:string = 'pie';
public JSONobject = {};
public isDataAvailable:boolean = false;
@ViewChild('mainChart') mainChart: BaseChartDirective; // ----- added
constructor(private predictionService: PredictionService){
this.getPredictions();
}
public getPredictions() {
this.predictionService.getPredictions('hello').do(result =>
this.populateChart(result)).subscribe();
}
public populateChart(obj): void {
let labels:string[] = [];
let data:number[] = [];
for (var i = 0; i < obj.predictions.length; i++)
{
labels.push(String(obj.predictions[i].class));
data.push(obj.predictions[i].percentage);
};
this.pieChartData = data;
this.mainChart.chart.config.data.labels = labels; // ---- updated
this.isDataAvailable = true;
}
public chartClicked(e:any):void {}
public chartHovered(e:any):void {}
}
In HTML add #{chartName} to access it
<div style="display: block" *ngIf="isDataAvailable">
<canvas #mainChart="base-chart" baseChart
[data]="pieChartData"
[labels]="pieChartLabels"
[chartType]="pieChartType"
(chartHover)="chartHovered($event)"
(chartClick)="chartClicked($event)"></canvas>
</div>
回答4:
first you to be sure that the order of labels is matching the order of the data_set, so basicly you have these two variables :
private datasets_pie = [
{
label: "Commissions",
data: Array<any>(),
backgroundColor: Array<any>()
}
];
private labels_pie = Array<any>();
secondly i had the same issue with the colors, so i had to insert the colors manually, here is an example :
private chartColors: any[] = [{ backgroundColor: ["#FFA1B5", "#7B68EE", "#87CEFA", "#B22222", "#FFE29A", "#D2B48C", "#90EE90", "#FF69B4", "#EE82EE", "#6A5ACD", "#b8436d", "#9ACD32", "#00d9f9", "#800080", "#FF6347", "#DDA0DD", "#a4c73c", "#a4add3", "#008000", "#DAA520", "#00BFFF", "#2F4F4F", "#FF8C00", "#A9A9A9", "#FFB6C1", "#00FFFF", "#6495ED", "#7FFFD4", "#F0F8FF", "#7FFF00", "#008B8B", "#9932CC", "#E9967A", "#8FBC8F", "#483D8B", "#D3D3D3", "#ADD8E6"] }];
finally after creating these object properly, you have to call this function :
setTimeout(() => {
if (this.chart && this.chart.chart && this.chart.chart.config) {
this.chart.chart.config.data.labels = this.labels_pie;
this.chart.chart.config.data.datasets = this.datasets_pie;
this.chart.chart.config.data.colors = this.chartColors;
this.chart.chart.update();
}
this.sommeStat = this.getSomme();
});
so i think that this might work :
import { Component, ViewChild, ElementRef } from '@angular/core';
import { ChartsModule } from 'ng2-charts';
import { PredictionService } from './prediction.service';
import { BaseChartDirective } from 'ng2-charts/ng2-charts';
@Component({
selector: 'prediction-result-chart',
templateUrl: './predictionResultChart.component.html'
})
export class PredictionResultChartComponent{
@ViewChild(BaseChartDirective) chart: BaseChartDirective;
public pieChartType: string = 'doughnut';
//public lineChartType: string = 'line';
private datasets_pie = [
{
label: "Commissions",
data: Array<any>(),
backgroundColor: Array<any>()
}
];
private labels_pie = Array<any>();
//private datasets_line : LineData[] = [];
// private datasets_line : { label : string, data : Array<any>}[] ;
// private labels_line = Array<any>();
private chartColors: any[] = [{ backgroundColor: ["#FFA1B5", "#7B68EE", "#87CEFA", "#B22222", "#FFE29A", "#D2B48C", "#90EE90", "#FF69B4", "#EE82EE", "#6A5ACD", "#b8436d", "#9ACD32", "#00d9f9", "#800080", "#FF6347", "#DDA0DD", "#a4c73c", "#a4add3", "#008000", "#DAA520", "#00BFFF", "#2F4F4F", "#FF8C00", "#A9A9A9", "#FFB6C1", "#00FFFF", "#6495ED", "#7FFFD4", "#F0F8FF", "#7FFF00", "#008B8B", "#9932CC", "#E9967A", "#8FBC8F", "#483D8B", "#D3D3D3", "#ADD8E6"] }];
private options = {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
};
public JSONobject = {}
constructor(private predictionService: PredictionService){
this.getPredictions();
}
public getPredictions() {
this.predictionService.getPredictions('hello').do(result => this.populateChart(result)).subscribe();
}
public populateChart(obj): void{
this.labels_pie = [];
this.datasets_pie[0]['data'] = [];
for (var i = 0; i < obj.predictions.length; i++)
{
labels.push(String(obj.predictions[i].class));
this.datasets_pie[0]['data'].push(obj.predictions[i].percentage);
};
let arrColors: any[];
arrColors = arrColorsCopy.splice(0, this.products.length);
this.datasets_pie[0]['backgroundColor'] = arrColors;
setTimeout(() => {
if (this.chart && this.chart.chart && this.chart.chart.config) {
this.chart.chart.config.data.labels = this.labels_pie;
this.chart.chart.config.data.datasets = this.datasets_pie;
this.chart.chart.config.data.colors = this.chartColors;
this.chart.chart.update();
}
});
}
public chartClicked(e:any):void {}
public chartHovered(e:any):void {}
}
for the html it should be looking like this :
<div class="col-md-8">
<div class="chart">
<canvas baseChart [datasets]="datasets_pie" [labels]="labels_pie" [chartType]="pieChartType" [colors]="chartColors"> </canvas>
</div>
</div>
thats all, you should try this way, it should work
来源：https://stackoverflow.com/questions/43204025/angular2-update-ng2-charts-with-labels