Error in v-on handler: "TypeError: Cannot read property 'clickData' of undefined"

方法来源

首先确认 

this.$refs[formName].validate((valid) => {

$ref 和 $refs 中名称相同

<ContentsUp ref="ContentsUp" :keyItemUrl="keyItem"/>
--------------

this.$refs.ContentsUp.clickData();

然后添加$nextTick

this.$nextTick(function () {
  this.$refs.ContentsUp.clickData();
});

此时修复报错！