vue2.0 element-ui中el-select选择器无法显示选中的内容(解决方法)

<template> <div> <div class="row" v-for="RowItem in rows">  <div class="col" v-for="colItem in RowItem.configVos">  <el-select v-model="formData[colItem.paramCode]" :class="getModel(colItem.paramCode)" @change="onSelectChange(colItem.paramCode,formData[colItem.paramCode])">   <el-option v-for="option in colItem.configOptions" :label="option.optionCode"    :value="option.optionValue" >   </el-option> </el-select>  </div>  </div>  </div> </template><script> import axios from 'axios'; export default { data() {  return {  groupItem:{},  formData:{},  rows:'',  cols:''  } }, watch:{ }, methods:{    getfordata:function(){  var _this = this;  axios.get('../json/selectdata.json')  .then(function(res){   _this.groupItem = res.data;   var row = _this.groupItem[0].rowData;   _this.rows = row;     for(var i=0;i<row.length;i++){   var col = row[i].configVos;      for(var j=0;j<col.length;j++){     var key = col[j];        _this.formData[key.paramCode] = '';     }   }     })  },  onSelectChange:function(key,val){  console.log(val);  },  getModel(model) {  console.log(model);  } }, created:function(){  this.getfordata(); } }</script><style scoped> .col{ float:left; } .row{ width:800px; height:100px; }</style>

[ { "groupName": "抽数转换", "rowData": [ { "configVos": [  {  "configOptions": [  {  "id": "D",  "optionCode": "否",  "optionValue": "0",  "paramId": "4"  },  {  "id": "5",  "optionCode": "是",  "optionValue": "1",  "paramId": "4"  }  ],  "id": "4E",  "paramCode": "isView",  "paramValue": "0"  },  {  "configOptions": [  {  "id": "4",  "optionCode": "老版本",  "optionValue": "0",  "paramId": "4"  },  {  "id": "4",  "optionCode": "新版本",  "optionValue": "1",  "paramId": "44"  }  ],  "id": "24",  "paramCode": "isDeleteCbnd",  "paramValue": "1"  } ] }, { "configVos": [  {  "configOptions": [  {  "id": "EF",  "optionCode": "估值2.5",  "optionValue": "0",  "paramId": "1"  },  {  "id": "8B",  "optionCode": "估值2.5+qd",  "optionValue": "1",  "paramId": "131"  },  {  "id": "06",  "optionCode": "恒生2.5",  "optionValue": "2",  "paramId": "1"  },  {  "id": "25BF",  "optionCode": "估值4.5",  "optionValue": "3",  "paramId": "31"  }  ],  "id": "31",  "paramCode": "converType",  "paramValue": "0"  },  {  "configOptions": [  {  "id": "1366",  "optionCode": "万德",  "optionValue": "0",  "paramId": "98"  },  {  "id": "EC",  "optionCode": "聚源",  "optionValue": "1",  "paramId": "8"  }  ],  "id": "91F8",  "paramCode": "zxDataSource",  "paramValue": "0"  } ] }, { "configVos": [  {  "configOptions": [  {  "id": "CD",  "optionCode": "期货占用",  "optionValue": "HS",  "paramId": "5C"  },  {  "id": "91508011",  "optionCode": "其它",  "optionValue": "YYS",  "paramId": "91C"  }  ],  "id": "5C",  "paramCode": "derivativeDataSource",  "paramValue": "HS"    } ] } ] }]