浅谈Vue Element中Select下拉框选取值的问题

<el-select v-model="ite" placeholder="请选择" value-key="mateGroup"> 
   <el-option style="width: auto" :disabled="true" :value="null"> 
    <span style="float: left;font-weight: bold">周次 </span> 
    <span style="float: left; color: #8492a6; font-size: 13px; font-weight: bold"> 开始日期 </span> 
    <span style="float: right; color: #8492a6; font-size: 13px; font-weight: bold"> 截止日期 </span> 
   </el-option> 
   <el-option v-for="(item,index) in res" :key="index" :label="item.mateGroup" v-bind:value="item"> 
    <span style="float: left; color: #8492a6; font-size: 13px">{{ item.mateGroup }} </span> 
    <span style="float: left; color: #8492a6; font-size: 13px"> {{ item.weekStartDate }}  </span> 
    <span style="float: right">{{ item.weekEndDate }}</span> 
   </el-option> 
  </el-select> 

<script>
 import jQuery from 'jquery'
 export default {
  props: ['orgCode', 'farmOrg'],
  data () {
   return {
    res: [],
    ite: '',
    weekse: ''
   }
  },
  created: function () {
   var _self = this
   _self.getWeekYearly()
  },
  watch: {
   ite: function (val) {
    this.weekse = val
    console.log(this.weekse)
    this.getL()
   }
  },
  methods: {
   getWeekYearly () {
    var _self = this
    jQuery.ajax({
     url: '/standard/' + _self.orgCode + '/' + _self.farmOrg + '/getWeekly',
     type: 'GET',
     // contentType: 'application/json',
     dataType: 'json',
     success: function (res) {
      _self.res = res
     },
     fail: function (e) {
//      this.tableFlag = false
      alert('请求失败')
      console.log('查询失败')
     }
    })
   },
   getL: function () {
    var _self = this
    _self.$emit('getL', _self.weekse)
   }
  }
 }
</script>