使用react-vant上传图片遇到的问题

<Form.Item
                        rules={[{ required: true, message: '请上传头像' }]}
                        label='上传头像'
                        name='files'
                    >
                        <Uploader accept='*' maxCount="1" onChange={imgFile} />
                    </Form.Item>

 const imgFile = (file) => {
        if (file.length !== 0) {
            console.log(file.length !== 0);
            let parm = new FormData()
            parm.append('file', file[0].file)
            console.log(file);
            axios({
                url: "url",
                method: "post",
                data: parm
            }).then(res => {
                console.log(res); //成功回调
                avatar = `url${res.data.url}`
                console.log(avatar);
                Toast.success('上传成功')
            })
                .catch(err => {
                    console.log(err); //失败回调
                });
        }
    }