如何让Vue组件等待数据准备好渲染? [英] How to let vue component wait until the data is ready for render?

问题描述

vue组件不会等待使用axios get从控制器获取数据，它会提示错误:

vue component won't wait for data from controller using axios get, it prompt error:

index.vue?d4c7:200未捕获(已承诺)TypeError:无法读取未定义的属性'ftth'

index.vue?d4c7:200 Uncaught (in promise) TypeError: Cannot read property 'ftth' of undefined

我的代码如下:

<template>
    <div class="dashboard-editor-container">
        <el-row style="background:#fff;padding:16px 16px 0;margin-bottom:32px;">
            <line-chart :chart-data="lineChartData"/>
        </el-row>
    </div>
</template>

<script>
    import LineChart from './components/LineChart';
    import axios from 'axios';

    const lineChartData = {
        all: {
            FTTHData: [],
            VDSLData: [],
            ADSLData: [],
        },
    };
    export default {
        name: 'Dashboard',
        components: {
            LineChart,
        },
        data() {
            return {
                lineChartData: lineChartData.all,
            };
        },
        created() {
            this.getData();
        },
        methods: {
            handleSetLineChartData(type) {
                this.lineChartData = lineChartData[type];
            },
            async getData() {
                axios
                    .get('/api/data_graphs')
                    .then(response => {
                        console.log(response.data);
                        var data = response.data;
                        var i = 0;
                        for (i = Object.keys(data).length - 1; i >= 0; i--) {
                            lineChartData.all.FTTHData.push(data[i]['ftth']);
                            lineChartData.all.VDSLData.push(data[i]['vdsl']);
                            lineChartData.all.ADSLData.push(data[i]['adsl']);
                        }
                    });
            },
        },
    };
</script>

我必须使用监视方法吗?

Do I have to use watch method?

推荐答案

首先，由于您具有这样的嵌套数据结构，因此您需要一个计算属性来返回是否加载数据.通常，您可以在模板中执行此检查.

First, because you have such a nested data structure you'll want a computed property to return whether the data is loaded or not. Normally, you could do this check in the template.

computed: {
  isDataLoaded() {
    const nestedLoaded = Object.keys(this.lineChartData).map(key => this.lineChartData[key].length !== 0)
    return this.lineChartData && nestedLoaded.length !== 0
  }
}

您可以使用 v-if ="isDataLoaded" 隐藏元素，直到数据加载完毕.

You can use v-if="isDataLoaded" to hide the element until the data has been loaded.

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