错误：7 PERMISSION_DENIED：权限缺失或不足

Question

尝试使用云函数写入集合并出现此错误。我相信 Firestore 应该以管理员权限运行，所以这个错误是相当矛盾的。

我的函数代码如下：

const express = require("express");
const app = express();
app.use(express.json());

// Import and initialize the Firebase Admin SDK.
const functions = require('firebase-functions');
// To set the region of all cloud functions
const rf = functions.region('europe-west2');

//FIREBASE ADMIN RIGHTS
const admin = require('firebase-admin');
admin.initializeApp();
var db = admin.firestore();

exports.saveOrder = rf.https.onRequest( async (req, res) => {
  console.log('-----saveOrder Triggered-------')
  let order;
  try{
    //console.log(req.body)
    order = req.body;
    order = order['order']
    let snap = await db.collection(`Restaurant/${order['key']}/open_orders`).doc(order['orderUID']).get() // error triggering line
    ...
    } else {
      ...
      }
    }
  } catch (error) {
   console.log(error)
    console.log('-------------saveOrder Triggered ERROR----------------')
    res.sendStatus(500)
    return
  }
  res.sendStatus(200);
})

错误如下：Error: 7 PERMISSION_DENIED: Missing or insufficient permissions.