vue-cli 中的反应性属性错误

Question

你好，

vue-cli 有一些问题。 我尝试显示（在主组件中）在输入中（在子组件中）输入的文本。它的工作（很奇怪）但有一条错误消息：

vue.esm.js?efeb:578 [Vue warn]: Property or method "test" is not 
defined on the instance but referenced during render. Make sure that 
this property is reactive, either in the data option, or for class-
based components, by initializing the property. See: 
https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-
Properties.

found in

---> <Signup> at src/components/auth/Signup.vue
       <App> at src/App.vue
         <Root>

我在互联网上搜索了很多示例来解决此错误，但没有使用架构 vue-cli。没看懂……

一步一步：

我写了一个组件：

<template>
   <div class="container">
     <p>{{ data.test }}</p>
     <form @submit.prevent="signup">
      <v-customInput v-model="test" @onChangeValue="onChange"></v-customInput>
     </form>
   </div>
</template>

<script>
  import CustomInput from '../shared/CustomInput'

 export default {
   name: 'HelloWorld',
   components: {
    'v-customInput': CustomInput,
   },
   data() {
     return {
       data: {
         test: '',
         first_name: '',
         last_name: '',
         email: '',
         password: '',
         vat: 0,
         creation_company_date: new Date(),
         phone: '',
       },
       error: false,
     };
    },
    methods: {
     onChange(variable) {
       const data = this.data;
        for (let value in data) {
         if (value === 'test') {
           data[value] = variable;
         }
        }
     }
   },
 };
</script>

和一个子组件：

<template>
  <div class="customInput">
    <input v-model="value" type="text">
    <label>First Name</label>

<script>
 export default {
  name: 'CustomInput',
  data() {
    return {
      value: '',
    };
  },
  watch: {
    value: function(val, oldVal) {
      this.$emit('onChangeValue', this.value);
    }
  },
 };
</script>

Answer 1

在 vue-2.x 中，如果您使用 v-model 绑定一个属性并且该属性不存在（在这种情况下为test），那么您将收到错误。

试试这个：添加test属性。

<template>
   <div class="container">
     <p>{{ data.test }}</p>
     <form @submit.prevent="signup">
      <v-customInput v-model="test" @onChangeValue="onChange"></v-customInput>
     </form>
   </div>
</template>

<script>
  import CustomInput from '../shared/CustomInput'

 export default {
   name: 'HelloWorld',
   components: {
    'v-customInput': CustomInput,
   },
   data() {
     return {
       test: '', // <===== initialize test with a default value
       data: {
         test: '',
         first_name: '',
         last_name: '',
         email: '',
         password: '',
         vat: 0,
         creation_company_date: new Date(),
         phone: '',
       },
       error: false,
     };
    },
    methods: {
     onChange(variable) {
       const data = this.data;
        for (let value in data) {
         if (value === 'test') {
           data[value] = variable;
         }
        }
     }
   },
 };
</script>