element-ui中的select下拉列表设置默认值方法

<template>
 <el-select v-model="value" placeholder="请选择">
 <el-option
  v-for="item in options"
  :key="item.value"
  :label="item.label"
  :value="item.value">
 </el-option>
 </el-select>
</template>

<script>
 export default {
 data() {
  return {
  options: [{
   value: '选项1',
   label: '黄金糕'
  }, {
   value: '选项2',
   label: '双皮奶'
  }, {
   value: '选项3',
   label: '蚵仔煎'
  }, {
   value: '选项4',
   label: '龙须面'
  }, {
   value: '选项5',
   label: '北京烤鸭'
  }],
  value: ''
  }
 }
 }
</script>

<template>
 <el-select v-model="value" placeholder="请选择">
 <el-option
  v-for="item in options"
  :key="item.value"
  :label="item.label"
  :value="item.value">
 </el-option>
 </el-select>
</template>

<script>
 export default {
 data() {
  return {
  options: [{
   value: '0',
   label: '全部'
  }, {
   value: '1',
   label: '待收款'
  }, {
   value: '2',
   label: '已收款'
  }, {
   value: '3',
   label: '已发货'
  },
  value: '全部'
  }
 }
 }
</script>

onSearch () {
 // console.log('value是' + this.value)
 if (this.value === '全部') {
  this.value = '0'
 }
}

<el-select v-model="form.admin_type" placeholder="所在分组" ><el-option v-for="item in selectItem" :label="item.dict_desc" :value="item.dict_id" :key="item.dict_id"></el-option></el-select>