vue2.0 element-ui中的el-select选择器无法显示选中的内容

我使用的是element-ui V2.2.3。代码如下，当我选择值得时候，el-select选择器无法显示选中的内容，但是能触发change方法，并且能输出选择的值。

select.vue文件

<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>

selectdata.json文件

[{"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"           }]}]}
]