vue中使用elementUI組件的Upload 上傳圖片

1.訪問Element官網【組件–Upload上傳】

<el-upload
  action="https://jsonplaceholder.typicode.com/posts/"
  list-type="picture-card"
  :on-preview="handlePictureCardPreview"
  :on-remove="handleRemove">
  <i class="el-icon-plus"></i>
</el-upload>
<el-dialog :visible.sync="dialogVisible">
  <img width="100%" :src="dialogImageUrl" alt="">
</el-dialog>
<script>
  export default {
    data() {
      return {
        dialogImageUrl: '',
        dialogVisible: false
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePictureCardPreview(file) {
        this.dialogImageUrl = file.url;
        this.dialogVisible = true;
      }
    }
  }
</script>

2.我的需求：點擊保存按鈕手動上傳，只能上傳一張圖片，參數爲userId

3.script中的data( )和methods( )如下：

<script>
  export default {
    data() {
      return {
      	file:'',
        dialogImageUrl: '',
        dialogVisible: false,
        imgUrl:'',
        userId: '',
        uid:'',
        
        // 上傳圖片時附帶的額外參數userId
        resData:{
        	userId: window.localStorage["userId"]
        },
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePictureCardPreview(file) {
        this.dialogImageUrl = file.url;
        this.dialogVisible = true;
      },
      
      // 點擊保存按鈕上傳圖片
      submit2:function(res){
		this.$refs.upload.submit();
	},
		
	// 圖片上傳成功後，後臺返回圖片的路徑
	onSuccess:function(res){
		// console.log(res);
		if(res.status==200){
			this.imgUrl=res.data.imgUrl;
		}
	},
    }
  }
</script>

4.該組件的效果圖如下：