Element UI Upload 上传文件只能上传一次 ，再次点击上传后无反应的问题

Element UI Upload 上传文件上传文件一次 ，不论是上传成功之后修改文件再上传还是上传失败重新上传，再次点击上传均无反应。

方法一：利用 :on-success

ref=‘upload’
:on-success=“handleSuccess”

注意：ref='upload 一定要加上ref 不然不起作用

                <el-upload
                        class="upload-demo"
                        action=""
                        :limit="1"
                        :show-file-list="false"
                        :http-request="uploadLogo"
                        ref='upload'
                        :on-success="handleSuccess"
                >
                    <el-button style="width: 150px; height: 35px;line-height: 0;margin-left: 20px" size="medium"
                               type="primary">
                        {{$t('StaffManage.bulkImport')}}
                    </el-button>
                </el-upload>

        handleSuccess(res, file) {
            this.$refs.upload.clearFiles(); //上传成功之后清除历史记录
            // this.tableReload()
        },

方法二：利用if el-upload让移除文档流

<el-upload
                        v-if="!form.contractFileUrl"class="upload-demo"action=""
                        :limit="1"
                        :show-file-list="false"
                        :http-request="uploadLogo"><el-buttonsize="medium"type="primary">{{$t('AttendanceInformation.ClickUpload')}}</el-button></el-upload>

            uploadLogo(param){let _this= this
                _this.form.contractFileUrl='1'let formData= new FormData();
                formData.append("file", param.file);
                _this.$send.post({url:'/contract/upload', data: formData}, res=>{if(res.code===10000){
                        _this.isdisabled=true
                        _this.form.contractFileUrl= res.data.url
                        _this.form.contractFileId= res.data.id}else{
                        _this.form.contractFileUrl= null
                        _this.form.contractFileId= null
                        _this.$msg.error(res.message)}})},