如何使用 Firebase 云功能向客户端（Swift）发送条带响应

Posted 2023-03-08

【中文标题】如何使用 Firebase 云功能向客户端（Swift）发送条带响应

【英文标题】：How to send stripe response to client side(Swift) using Firebase cloud function

【发布时间】：2019-07-13 16:35:06

【问题描述】：

我正在使用 Stripe 和 Firebase 作为后端制作像 Airbnb 这样的 ios 应用。我正在关注这个文件。 https://medium.com/firebase-developers/go-serverless-manage-payments-in-your-apps-with-cloud-functions-for-firebase-3528cfad770。 正如文档所述，这是我到目前为止所做的工作流程。（假设用户想要购买东西）1。用户将支付信息发送到 Firebase 实时数据库，例如金额货币和卡令牌）2。 Firebase 触发一个向 Stripe 发送收费请求（stripe.charge.create）的函数。 3。得到响应后，将其写回 Firebase 数据库。如果响应失败，则将错误消息写入数据库（参见 index.js 中的 userFacingMessage 函数）4.在客户端（Swift）中，观察 Firebase 数据库以检查响应。 5. 如果响应成功，向用户显示成功消息。如果出现任何错误，例如（支付失败，因为信用卡过期），向用户显示失败消息（同时显示“请重试”消息）我想这不是正确的方法，因为我认为一旦firebase从Stripe获得响应，用户应该知道响应（如果成功或失败）。换句话说，客户端（Swift）应该在得到响应后立即得到响应，然后再写回Firebase数据库？知道如何向客户端发送响应吗？ 任何帮助将不胜感激

ChargeViewController.swift（客户端）

  func didTapPurchase(for amountCharge: String, for cardId: String) 
    print("coming from purchas button", amountCharge, cardId)

    guard let uid = Auth.auth().currentUser?.uid else return

    guard let cardId = defaultCardId else return
    let amount = amountCharge
    let currency = "usd"

    let value = ["source": cardId, "amount": amount, "currency": currency] as [String: Any]

    let ref = Database.database().reference().child("users").child(uid).child("charges")
    ref.childByAutoId().updateChildValues(value)  (err, ref) in
        if let err = err 
            print("failed to inserted charge into db", err)
        

        print("successfully inserted charge into db")

       //Here, I want to get the response and display messages to user whether the response was successful or not.

    

index.js(云函数) 语言：node.js

exports.createStripeCharge = functions.database
.ref(‘users/userId/charges/id’)
.onCreate(async (snap, context) => 
const val = snap.data();
try 
// Look up the Stripe customer id written in createStripeCustomer
const snapshot = await admin.database()
.ref(`users/stripe/$context.params.userId/stripe_customer_id`)
.once('value');

const snapval = snapshot.data();
const customer = snapval.stripe_customer_id;
// Create a charge using the pushId as the idempotency key
// protecting against double charges
const amount = val.amount;
const idempotencyKey = context.params.id;
const charge = amount, currency, customer;
if (val.source !== null) 
   charge.source = val.source;

const response = await stripe.charges
    .create(charge, idempotency_key: idempotencyKey);
// If the result is successful, write it back to the database
//*I want to send this response to the client side but not sure how if I can do it nor not*
return snap.ref.set(response);
 catch(error) 
    await snap.ref.set(error: userFacingMessage(error));

);
    // Sanitize the error message for the user
function userFacingMessage(error) 
  return error.type ? error.message : 'An error occurred, developers have been alerted';

【参考方案1】：

基于Franks's post here，我决定等待 Firebase 数据库的更改。下面是工作流程和代码（index.js 文件没有变化）： 1. 用户在 /users/userId/charges 路径下向 Firebase 实时数据库发送支付信息，例如金额货币和卡令牌） 2. Firebase 触发向 Stripe 发送充电请求（stripe.charge.create）的函数。 3. 得到响应后，将其写回 Firebase 数据库。如果响应失败，则将错误消息写入数据库（请参阅 index.js 中的 userFacingMessage 函数） 4.在客户端（Swift），等待Firebase数据库的变化，使用Observe(.childChanged)检查响应是否成功（见Swift代码） 5. 如果响应成功，向用户显示成功消息。如果有任何错误，例如（由于信用卡过期而支付失败），向用户显示失败消息（同时显示“请重试”消息）

ChargeViewController.swift

func didTapPurchase(for amountCharge: String, for cardId: String) 
print("coming from purchas button", amountCharge, cardId)

guard let uid = Auth.auth().currentUser?.uid else return

guard let cardId = defaultCardId else return
let amount = amountCharge
let currency = "usd"

let value = ["source": cardId, "amount": amount, "currency": currency] as [String: Any]

let ref = Database.database().reference().child("users").child(uid).child("charges")
ref.childByAutoId().updateChildValues(value)  (err, ref) in
    if let err = err 
        print("failed to inserted charge into db", err)
    

    print("successfully inserted charge into db")

   //Here, Wait for the response that has been changed
   waitForResponseBackFromStripe(uid: uid)

  

 

func waitForResponseBackFromStripe(uid: String) 

    let ref = Database.database().reference().child("users").child(uid).child("charges")
    ref.observe(.childChanged, with:  (snapshot) in

        guard let dictionary = snapshot.value as? [String: Any] else return

        if let errorMessage = dictionary["error"] 
            print("there's an error happening so display error message")
            let alertController = UIAlertController(title: "Sorry:(\n \(errorMessage)", message: "Please try again", preferredStyle: .alert)
            alertController.addAction(UIAlertAction(title: "Ok", style: .cancel, handler: nil))
            //alertController.addAction(UIAlertAction(title: "Ok", style: .cancel, handler: nil))
            self.present(alertController, animated: true, completion: nil)
            return

         else 
            let alertController = UIAlertController(title: "Success!", message: "The charge was Successful", preferredStyle: .alert)
            alertController.addAction(UIAlertAction(title: "Ok", style: .cancel, handler: nil))
            self.present(alertController, animated: true, completion: nil)
        
    )  (err) in
        print("failed to fetch charge data", err.localizedDescription)
        return
    

如果我在逻辑上做错了什么，请告诉我。但到目前为止它对我有用 希望这对正在集成 Firebase 和 Stripe 支付的人有所帮助