我正在尝试将chart.js
与vue.js
组合使用。
我有一个名为MessageGraph
的组件,它看起来像这样(数据等来自文档):
<template>
<canvas id="myChart" width="400" height="400"></canvas>
</template>
<script>
import Chart from 'chart.js';
export default {
created() {
var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero:true
}
}]
}
}
});
}
}
</script>
但我在控制台中收到此错误:
app.c47f281….js:71222 [Vue warn]: Error in created hook:
(found in <MessageGraph> at /Users/Janssen/Code/forumv2/resources/assets/js/components/graph/MessageGraph.vue)
warn @ app.c47f281….js:71222
handleError @ app.c47f281….js:72107
callHook @ app.c47f281….js:72939
Vue._init @ app.c47f281….js:74420
VueComponent @ app.c47f281….js:74584
createComponentInstanceForVnode @ app.c47f281….js:73779
init @ app.c47f281….js:73587
createComponent @ app.c47f281….js:75318
createElm @ app.c47f281….js:75261
createChildren @ app.c47f281….js:75386
createElm @ app.c47f281….js:75294
createChildren @ app.c47f281….js:75386
createElm @ app.c47f281….js:75294
patch @ app.c47f281….js:75753
Vue._update @ app.c47f281….js:72697
updateComponent @ app.c47f281….js:72820
get @ app.c47f281….js:73131
Watcher @ app.c47f281….js:73114
mountComponent @ app.c47f281….js:72824
./node_modules/vue/dist/vue.common.js.Vue$3.$mount @ app.c47f281….js:77914
./node_modules/vue/dist/vue.common.js.Vue$3.$mount @ app.c47f281….js:79963
Vue._init @ app.c47f281….js:74430
Vue$3 @ app.c47f281….js:74511
./resources/assets/js/app.js @ app.c47f281….js:80091
__webpack_require__ @ app.c47f281….js:20
0 @ app.c47f281….js:80854
__webpack_require__ @ app.c47f281….js:20
(anonymous) @ app.c47f281….js:66
(anonymous) @ app.c47f281….js:69
app.c47f281….js:72111 TypeError: Cannot read property 'length' of null
at Object.acquireContext (app.c47f281….js:14468)
at new Chart.Controller (app.c47f281….js:7776)
at new Chart (app.c47f281….js:10193)
at VueComponent.created (app.c47f281….js:2106)
at callHook (app.c47f281….js:72937)
at VueComponent.Vue._init (app.c47f281….js:74420)
at new VueComponent (app.c47f281….js:74584)
at createComponentInstanceForVnode (app.c47f281….js:73779)
at init (app.c47f281….js:73587)
在我的app.js中,我添加了组件:
Vue.component('messageGraph', require('./components/graph/MessageGraph.vue'));
然后在我的appl.blade文件中,我有这样的内容:
<message-graph></message-graph>
有什么问题吗?
1条答案
按热度按时间mepcadol1#
您正在访问
created()
挂钩中的canvas元素,该挂钩在模板附加到DOM之前被调用。为了解决这个问题,你需要把代码放到组件的
mounted()
钩子中。但是,仍然不能保证模板在文档中。所以你必须使用$vm.nextTick()来确保DOM已经准备好。(源代码)。此外,我建议使用vue的Child组件refs,它比
document.getElementById()
更像vue(它也能工作)。第一个