uni.uploadFile上传参数丢失

就是参数中的para1后端获取到的是none
let formData={
"appid": appid,
"para1": '',
"unixtime": Date.parse(new Date()) / 1000,
"sign": this.EncryptDate(appid, appid + (Date.parse(new Date()) / 1000).toString() + ''),
}

const task = uni.uploadFile({
url: this.action,
filePath: this.lists[index].url,
name: this.name,
formData: formData,
header: this.header,
success: res => {
// 判断是否json字符串，将其转为json格式
let data = this.toJson && this.$u.test.jsonString(res.data) ? JSON.parse(res.data) : res.data;
if (![200, 201, 204].includes(res.statusCode)) {
this.uploadError(index, data);
} else {
// 上传成功
this.lists[index].response = data;
this.lists[index].progress = 100;
this.lists[index].error = false;
this.$emit('on-success', data, index, this.lists, this.index);
}
},
fail: e => {
this.uploadError(index, e);
},
complete: res => {
uni.hideLoading();
this.uploading = false;
this.uploadFile(index + 1);
this.$emit('on-change', res, index, this.lists, this.index);
}
});