vue报错Error in render: “TypeError: Cannot read property ‘length‘ of undefined“
原因： el-table 中（列表）属性中有为undefined,所有在列中加一个个v-if判断就可以了
<el-table-column label="数据库" width="500px">
<template slot="header">
<el-button
@click="counterElection('主键', 'sqlOpt')"
size="small"
type="default"
>主键
el-button>
<el-button
@click="counterElection('非空', 'sqlOpt')"
size="small"
type="default"
>非空
el-button>
<el-button
@click="counterElection('唯一', 'sqlOpt')"
size="small"
type="default"
>唯一
el-button>
<el-button
@click="counterElection('索引', 'sqlOpt')"
size="small"
type="default"
>索引
el-button>
<el-button
@click="counterElection('忽略', 'sqlOpt')"
size="small"
type="default"
>忽略
el-button>
<el-button
@click="counterElection('自增', 'sqlOpt')"
size="small"
type="default"
>自增
el-button>
template>
<template slot-scope="scope">
<el-checkbox-group
v-if="
scope.row !== undefined &&
scope.row.sqlOpt !== undefined
"
v-model="scope.row.sqlOpt"
>
<el-checkbox label="主键">el-checkbox>
<el-checkbox label="非空">el-checkbox>
<el-checkbox label="唯一">el-checkbox>
<el-checkbox label="索引">el-checkbox>
<el-checkbox label="忽略">el-checkbox>
<el-checkbox label="自增">el-checkbox>
el-checkbox-group>
template>
el-table-column>