el-upload 根据后端返回的参数设置动态action

需求：在一个表单中既要提交数据，又到提交图片，并且图片提交的url（ /**/**/pic？id=*）中某个参数(id)是提交数据后返回的。

HTML

 <el-upload
            class="upload-demo"
            name="file"  //对应后端接收参数名
            ref="upload"
            drag
            :action="newUrl" //设置绑定url
            :limit="1"
            :auto-upload="false" //关闭自动提交
            :headers="headers" 
            :on-success="uploadAttachmentSuccess"
            :on-error="uploadAttachmentfail"
            :before-upload="beforeUploadHandle" //提交前操作
          >
            <i class="el-icon-upload"></i>
            <div class="el-upload__text">
              将文件拖到此处，或<em>点击上传</em>
            </div>
            <div class="el-upload__tip" slot="tip">
              只能上传jpg/png文件，且不超过500kb
            </div>
          </el-upload>

<el-button type="primary" @click="handleAdd()">确 定</el-button>

JS
addObj将用于提交表单数据到后端，后端返回该条数据在数据库的id
this.newId = response.data.data//获取后端返回的参数
this.$refs.upload.submit()//手动提交

    handleAdd() {
      addObj({
        casnum: this.addContent.casnum,
        formulaPlain: this.addContent.formulaPlain,
        nameEn: this.addContent.nameEn,
        nameCn: this.addContent.nameCn,
        refText: this.addContent.ref_text,
        refLink: this.addContent.ref_link,
        refTitle: this.addContent.ref_title,
      })
        .then((response) => {
          //新增分子式后返回其id
          this.newId = response.data.data;
          this.addDetails = false;
          this.$message.success("添加成功");
          this.getList();
          this.addContent = {};
          this.$refs.upload.submit();
        })
        .catch(() => {
          this.$message.error("添加失败");
          this.addContent = {};
          this.addDetails = false;
        });
    },

上传前设置
这里设置对 :action=“newUrl” 进行参数绑定

    beforeUploadHandle(file) {
      return new Promise((resolve)=>{
        this.$nextTick(()=>{
          this.newUrl = "/**/**/pic?id=" + this.newId;
          resolve();
        })
      })
    },

后端接口代码
最后实际请求 /**/**/pic？id=22**//例如后端返回参数22

@PostMapping("/pic")
public R updatePic(@RequestParam("file") MultipartFile file, @RequestParam("id") int id){
		return (vocMolucularService.updatePic(file,id));
	}