Vue3基础知识点及与Vue2的区别

父组件向子组件传值

父组件中语法与Vue2一样，如：

<template>
  <el-form ref="formRef" :model="formData" :rules="rules" label-width="120px">
    <el-row>
      <el-col :span="12">
        <el-form-item label="表名称" prop="tableName">
          <el-input placeholder="请输入仓库名称" v-model="formData.tableName" />
        el-form-item>
      el-col>
    el-row>
  el-form>

  
  <UploadBatch
    ref="uploadBatchRef"
    :uploadDialogVisible="uploadBatchVisible"
    :fill-id="fillId"
    @set-visible="setVisible"
  />
template>

子组件UploadBatch在defineProps内接收：

<script setup lang="ts" name="UploadBatch">
const props = defineProps({
  uploadDialogVisible: { // Boolean类型
    type: Boolean,
    default: false
  },
  fillId: { // Number类型
    type: Number,
    default: null
  },
  boxNo: { // String类型
    type: String,
    default: ''
  },
  
  // 以下为其他类型演示！！！
  value: String,
  processId: String,
  processName: String,
  formId: Number,
  translations: {
    type: Object,
    default: () => {}
  },
  additionalModel: [Object, Array],
  moddleExtension: {
    type: Object,
    default: () => {}
  },
  prefix: {
    type: String,
    default: 'camunda'
  },
  events: {
    type: Array,
    default: () => ['element.click']
  },
  headerButtonSize: {
    type: String,
    default: 'small',
    validator: (value: string) => ['default', 'medium', 'small', 'mini'].indexOf(value) !== -1
  }
})
</script>

子组件中使用props的属性，可以用toRef和toRefs，取出来的属性还是响应式的，如：

const { fillId, uploadDialogVisible, boxNo } = toRefs(props) // 取出所有响应式属性
  
const fillId = toRef(props, 'fillId')	// 或者只取单个属性
console.log(fillId.value) 	// 要用.value取真正的值，否则只是个响应式对象！但在template模板中无需加.value

注意：严格遵循单向数据流，子组件不要修改父组件传过来的属性值！可以通过emit发给父组件一个通知让父组件自己去修改这个属性值！

---

子组件调用父组件事件（发送通知）

父组件中语法与Vue2一样，如：

<UploadBatch
  ref="uploadBatchRef"
  :uploadDialogVisible="uploadBatchVisible"
  :fill-id="fillId"
  @set-visible="setVisible"
  @reload-data="reloadData"
/>

<script setup lang="ts">
const setVisible = (value) => {
  uploadBatchVisible.value = value
  uploadPhotoVisible.value = value
}

const reloadData = (value) => {
  reviewAuditStatus.value = String(value.reviewAuditStatus)
  reasonForFailure.value = value.reasonForFailure
}
script>

子组件中定义defineEmits：

// 定义
const emit = defineEmits(['setVisible', 'reflsheData'])

// 然后通过emit调用父组件setVisible和reloadData方法
const close = () => {
  emit('setVisible', false)
  emit('reloadData', { reviewAuditStatus: flag.value, reasonForFailure: reasonForFailure.value })
}

---

父组件访问子组件属性及调用子组件方法

在子组件中使用Vue3的语法糖defineExpose：

<script setup lang="ts">
const initData = async (detailId, type) => {
  console.log(detailId)
  console.log(type)
  console.log('初始化数据...')
}
  
defineExpose({
  xGridRef: xGrid,
  info: props.info
  initData
})
</script>

父组件中：

<template>
  
    <UploadBatch
      ref="uploadBatchRef"
      :uploadDialogVisible="uploadBatchVisible"
      :fill-id="fillId"
      @set-visible="setVisible"
    />
template>

<script setup lang="ts">
  const uploadBatchRef = ref()

  uploadBatchRef.value?.initData(detailId.value, 1)
script>