upload I added a default image, but click submit does not trigger: http-request, must upload a file to trigger, how to solve this?

uploadImg is called by this method this.$refs.upload.submit ()

 
        <el-upload
            ref="upload"
            :headers="myHeaders"
            class="avatar-uploader avatar-uploaderOne"
            action="http://47.93.4.35:9090/shop/upload"
            :http-request="uploadImg"
            :show-file-list="false"
            :on-preview="handlePreview"
            :on-success="handleAvatarSuccess"
            :onSuccess="uploadSuccess"
            :on-change="handleChange"
            :before-upload="beforeAvatarUpload"
            :before-remove="beforeRemove"
            :auto-upload="false">
            <img v-if="true" :src="imageUrl" class="avatar">
            <i v-else class="el-icon-plus avatar-uploader-icon" style="margin-left: -20px"></i>
          </el-upload>