透過應用程式呼叫函式


Cloud Functions for Firebase 用戶端 SDK 可讓您直接從 Firebase 應用程式呼叫函式。如要透過這種方式從應用程式呼叫函式,請在 Cloud Functions 中編寫並部署 HTTP 可呼叫函式,然後新增用戶端邏輯,以便從應用程式呼叫函式。

請務必注意,HTTP 可呼叫函式與 HTTP 函式相似,但不相同。如要使用 HTTP 可呼叫函式,您必須使用平台的用戶端 SDK 搭配後端 API (或實作通訊協定)。可呼叫項與 HTTP 函式的主要差異如下:

  • 使用可呼叫項時,系統會自動將 Firebase Authentication 權杖、FCM 權杖和 App Check 權杖 (如有) 納入要求。
  • 觸發條件會自動對要求主體進行去序列化,並驗證驗證權杖。

Cloud Functions 第 2 代以上版本的 Firebase SDK 會與下列 Firebase 用戶端 SDK 最低版本互通,以支援 HTTPS 可呼叫函式:

  • Firebase 適用於 Apple 平台的 SDK 11.6.0
  • Firebase SDK for Android 21.1.0
  • Firebase Modular Web SDK 9.7.0 版

如果您想在未支援的平台上建構的應用程式中加入類似的功能,請參閱 https.onCall 的通訊協定規格。本指南的其餘部分會提供如何為 Apple 平台、Android、網頁、C++ 和 Unity 編寫、部署及呼叫 HTTP 可呼叫函式的操作說明。

編寫及部署可呼叫的函式

本節的程式碼範例是根據完整的快速入門範例編寫,說明如何傳送要求至伺服器端函式,並使用其中一個用戶端 SDK 取得回應。如要開始使用,請匯入必要的模組:

Node.js

// Dependencies for callable functions.
const {onCall, HttpsError} = require("firebase-functions/v2/https");
const {logger} = require("firebase-functions/v2");

// Dependencies for the addMessage function.
const {getDatabase} = require("firebase-admin/database");
const sanitizer = require("./sanitizer");

Python

# Dependencies for callable functions.
from firebase_functions import https_fn, options

# Dependencies for writing to Realtime Database.
from firebase_admin import db, initialize_app

使用平台的請求處理常式 (functions.https.onCall) 或 on_call) 建立 HTTPS 可呼叫函式。這個方法會接收要求參數:

Node.js

// Saves a message to the Firebase Realtime Database but sanitizes the
// text by removing swearwords.
exports.addmessage = onCall((request) => {
  // ...
});

Python

@https_fn.on_call()
def addmessage(req: https_fn.CallableRequest) -> Any:
    """Saves a message to the Firebase Realtime Database but sanitizes the text
    by removing swear words."""

request 參數包含從用戶端應用程式傳遞的資料,以及驗證狀態等額外背景資訊。舉例來說,如果可呼叫函式將文字訊息儲存至 Realtime Databasedata 可包含訊息文字,以及 auth 中的驗證資訊:

Node.js

// Message text passed from the client.
const text = request.data.text;
// Authentication / user information is automatically added to the request.
const uid = request.auth.uid;
const name = request.auth.token.name || null;
const picture = request.auth.token.picture || null;
const email = request.auth.token.email || null;

Python

# Message text passed from the client.
text = req.data["text"]
# Authentication / user information is automatically added to the request.
uid = req.auth.uid
name = req.auth.token.get("name", "")
picture = req.auth.token.get("picture", "")
email = req.auth.token.get("email", "")

可呼叫函式的位置與呼叫用戶端的位置之間的距離,可能會造成網路延遲。為提升效能,建議您在適用情況下指定函式位置,並確保在用戶端初始化 SDK時,呼叫端位置與設定的位置一致。

您可以選擇附加 App Check 認證,以保護後端資源,避免遭到帳單詐欺或網路釣魚等濫用行為影響。請參閱「Cloud Functions 啟用 App Check 強制執行功能」。

傳回結果

如要將資料傳回至用戶端,請傳回可進行 JSON 編碼的資料。舉例來說,如要傳回加法運算的結果:

Node.js

// returning result.
return {
  firstNumber: firstNumber,
  secondNumber: secondNumber,
  operator: "+",
  operationResult: firstNumber + secondNumber,
};

Python

return {
    "firstNumber": first_number,
    "secondNumber": second_number,
    "operator": "+",
    "operationResult": first_number + second_number
}

訊息文字範例經過淨化的文字會傳回給用戶端和 Realtime Database。在 Node.js 中,您可以使用 JavaScript 承諾以非同步方式執行這項操作:

Node.js

// Saving the new message to the Realtime Database.
const sanitizedMessage = sanitizer.sanitizeText(text); // Sanitize message.

return getDatabase().ref("/messages").push({
  text: sanitizedMessage,
  author: {uid, name, picture, email},
}).then(() => {
  logger.info("New Message written");
  // Returning the sanitized message to the client.
  return {text: sanitizedMessage};
})

Python

# Saving the new message to the Realtime Database.
sanitized_message = sanitize_text(text)  # Sanitize message.
db.reference("/messages").push({  # type: ignore
    "text": sanitized_message,
    "author": {
        "uid": uid,
        "name": name,
        "picture": picture,
        "email": email
    }
})
print("New message written")

# Returning the sanitized message to the client.
return {"text": sanitized_message}

設定 CORS (跨源資源共享)

使用 cors 選項控管哪些來源可以存取函式。

根據預設,可呼叫的函式會將 CORS 設為允許來自所有來源的要求。如要允許部分跨來源要求 (但不是所有要求),請傳遞應允許的特定網域或規則運算式清單。例如:

Node.js

const { onCall } = require("firebase-functions/v2/https");

exports.getGreeting = onCall(
  { cors: [/firebase\.com$/, "https://flutter.com"] },
  (request) => {
    return "Hello, world!";
  }
);

如要禁止跨來源要求,請將 cors 政策設為 false

處理錯誤

為確保用戶端能取得實用的錯誤詳細資料,請擲回 (或在 Node.js 傳回遭拒絕的 Promise) functions.https.HttpsErrorhttps_fn.HttpsError 的例項,藉此從可呼叫的項目傳回錯誤。錯誤包含 code 屬性,可為 gRPC 狀態碼 中列出的其中一個值。錯誤也包含字串 message,預設為空字串。也可以含有選用的 details 欄位,其中含有任意值。如果函式擲回的不是 HTTPS 錯誤,而是其他錯誤,您的用戶端會收到錯誤訊息,其中包含訊息 INTERNAL 和代碼 internal

舉例來說,函式可以擲回資料驗證和驗證錯誤,並傳回錯誤訊息給呼叫端用戶端:

Node.js

// Checking attribute.
if (!(typeof text === "string") || text.length === 0) {
  // Throwing an HttpsError so that the client gets the error details.
  throw new HttpsError("invalid-argument", "The function must be called " +
          "with one arguments \"text\" containing the message text to add.");
}
// Checking that the user is authenticated.
if (!request.auth) {
  // Throwing an HttpsError so that the client gets the error details.
  throw new HttpsError("failed-precondition", "The function must be " +
          "called while authenticated.");
}

Python

# Checking attribute.
if not isinstance(text, str) or len(text) < 1:
    # Throwing an HttpsError so that the client gets the error details.
    raise https_fn.HttpsError(code=https_fn.FunctionsErrorCode.INVALID_ARGUMENT,
                              message=('The function must be called with one argument, "text",'
                                       " containing the message text to add."))

# Checking that the user is authenticated.
if req.auth is None:
    # Throwing an HttpsError so that the client gets the error details.
    raise https_fn.HttpsError(code=https_fn.FunctionsErrorCode.FAILED_PRECONDITION,
                              message="The function must be called while authenticated.")

部署可呼叫的函式

index.js 中儲存完成的呼叫函式後,執行 firebase deploy 時,系統會將該函式與所有其他函式一併部署。如要只部署可呼叫項目,請使用 --only 引數,如圖所示,執行部分部署

firebase deploy --only functions:addMessage

如果在部署函式時遇到權限錯誤,請務必將適當的 IAM 角色指派給執行部署指令的使用者。

設定用戶端開發環境

請確認您已符合所有先決條件,然後將必要的依附元件和用戶端程式庫新增至應用程式。

iOS+

按照操作說明將 Firebase 新增至 Apple 應用程式

使用 Swift Package Manager 安裝及管理 Firebase 依附元件。

  1. 在 Xcode 中保持開啟應用程式專案,然後依序點選「File」>「Add Packages」
  2. 系統提示時,請新增 Firebase Apple 平台 SDK 存放區:
  3.   https://github.com/firebase/firebase-ios-sdk.git
  4. 選擇 Cloud Functions 程式庫。
  5. -ObjC 標記新增至目標的建構設定「Other Linker Flags」部分。
  6. 完成後,Xcode 就會自動開始在背景中解析並下載依附元件。

Web

  1. 按照操作說明將 Firebase 新增至網路應用程式。請務必透過終端機執行下列指令:
    npm install firebase@11.0.2 --save
  2. 手動要求 Firebase 核心和 Cloud Functions

     import { initializeApp } from 'firebase/app';
     import { getFunctions } from 'firebase/functions';
    
     const app = initializeApp({
         projectId: '### CLOUD FUNCTIONS PROJECT ID ###',
         apiKey: '### FIREBASE API KEY ###',
         authDomain: '### FIREBASE AUTH DOMAIN ###',
       });
     const functions = getFunctions(app);

Android

  1. 按照操作說明將 Firebase 新增至 Android 應用程式

  2. 模組 (應用程式層級) Gradle 檔案 (通常為 <project>/<app-module>/build.gradle.kts<project>/<app-module>/build.gradle) 中,加入 Android 的 Cloud Functions 程式庫依附元件。建議您使用 Firebase Android BoM 來控制程式庫版本。

    dependencies {
        // Import the BoM for the Firebase platform
        implementation(platform("com.google.firebase:firebase-bom:33.7.0"))
    
        // Add the dependency for the Cloud Functions library
        // When using the BoM, you don't specify versions in Firebase library dependencies
        implementation("com.google.firebase:firebase-functions")
    }

    只要使用 Firebase Android BoM,應用程式就會一律使用相容的 Firebase Android 程式庫版本。

    (替代做法)  使用 BoM 新增 Firebase 程式庫依附元件

    如果您選擇不使用 Firebase BoM,則必須在依附元件行中指定每個 Firebase 程式庫版本。

    請注意,如果您在應用程式中使用多個 Firebase 程式庫,強烈建議您使用 BoM 來管理程式庫版本,確保所有版本皆相容。

    dependencies {
        // Add the dependency for the Cloud Functions library
        // When NOT using the BoM, you must specify versions in Firebase library dependencies
        implementation("com.google.firebase:firebase-functions:21.1.0")
    }
    想尋找 Kotlin 專屬的程式庫模組嗎?2023 年 10 月 (Firebase BoM 32.5.0)起,Kotlin 和 Java 開發人員都可以依附主要程式庫模組 (詳情請參閱這項計畫的常見問題)。

初始化用戶端 SDK

初始化 Cloud Functions 的例項:

Swift

lazy var functions = Functions.functions()

Objective-C

@property(strong, nonatomic) FIRFunctions *functions;
// ...
self.functions = [FIRFunctions functions];

Web

const app = initializeApp({
  projectId: '### CLOUD FUNCTIONS PROJECT ID ###',
  apiKey: '### FIREBASE API KEY ###',
  authDomain: '### FIREBASE AUTH DOMAIN ###',
});
const functions = getFunctions(app);

Kotlin

private lateinit var functions: FirebaseFunctions
// ...
functions = Firebase.functions

Java

private FirebaseFunctions mFunctions;
// ...
mFunctions = FirebaseFunctions.getInstance();

呼叫函式

Swift

functions.httpsCallable("addMessage").call(["text": inputField.text]) { result, error in
  if let error = error as NSError? {
    if error.domain == FunctionsErrorDomain {
      let code = FunctionsErrorCode(rawValue: error.code)
      let message = error.localizedDescription
      let details = error.userInfo[FunctionsErrorDetailsKey]
    }
    // ...
  }
  if let data = result?.data as? [String: Any], let text = data["text"] as? String {
    self.resultField.text = text
  }
}

Objective-C

[[_functions HTTPSCallableWithName:@"addMessage"] callWithObject:@{@"text": _inputField.text}
                                                      completion:^(FIRHTTPSCallableResult * _Nullable result, NSError * _Nullable error) {
  if (error) {
    if ([error.domain isEqual:@"com.firebase.functions"]) {
      FIRFunctionsErrorCode code = error.code;
      NSString *message = error.localizedDescription;
      NSObject *details = error.userInfo[@"details"];
    }
    // ...
  }
  self->_resultField.text = result.data[@"text"];
}];

Web

var addMessage = firebase.functions().httpsCallable('addMessage');
addMessage({ text: messageText })
  .then((result) => {
    // Read result of the Cloud Function.
    var sanitizedMessage = result.data.text;
  });

Web

import { getFunctions, httpsCallable } from "firebase/functions";

const functions = getFunctions();
const addMessage = httpsCallable(functions, 'addMessage');
addMessage({ text: messageText })
  .then((result) => {
    // Read result of the Cloud Function.
    /** @type {any} */
    const data = result.data;
    const sanitizedMessage = data.text;
  });

Kotlin

private fun addMessage(text: String): Task<String> {
    // Create the arguments to the callable function.
    val data = hashMapOf(
        "text" to text,
        "push" to true,
    )

    return functions
        .getHttpsCallable("addMessage")
        .call(data)
        .continueWith { task ->
            // This continuation runs on either success or failure, but if the task
            // has failed then result will throw an Exception which will be
            // propagated down.
            val result = task.result?.data as String
            result
        }
}

Java

private Task<String> addMessage(String text) {
    // Create the arguments to the callable function.
    Map<String, Object> data = new HashMap<>();
    data.put("text", text);
    data.put("push", true);

    return mFunctions
            .getHttpsCallable("addMessage")
            .call(data)
            .continueWith(new Continuation<HttpsCallableResult, String>() {
                @Override
                public String then(@NonNull Task<HttpsCallableResult> task) throws Exception {
                    // This continuation runs on either success or failure, but if the task
                    // has failed then getResult() will throw an Exception which will be
                    // propagated down.
                    String result = (String) task.getResult().getData();
                    return result;
                }
            });
}

Dart

    final result = await FirebaseFunctions.instance.httpsCallable('addMessage').call(
      {
        "text": text,
        "push": true,
      },
    );
    _response = result.data as String;

C++

firebase::Future<firebase::functions::HttpsCallableResult> AddMessage(
    const std::string& text) {
  // Create the arguments to the callable function.
  firebase::Variant data = firebase::Variant::EmptyMap();
  data.map()["text"] = firebase::Variant(text);
  data.map()["push"] = true;

  // Call the function and add a callback for the result.
  firebase::functions::HttpsCallableReference doSomething =
      functions->GetHttpsCallable("addMessage");
  return doSomething.Call(data);
}

Unity

private Task<string> addMessage(string text) {
  // Create the arguments to the callable function.
  var data = new Dictionary<string, object>();
  data["text"] = text;
  data["push"] = true;

  // Call the function and extract the operation from the result.
  var function = functions.GetHttpsCallable("addMessage");
  return function.CallAsync(data).ContinueWith((task) => {
    return (string) task.Result.Data;
  });
}

處理用戶端的錯誤

如果伺服器擲回錯誤,或是產生的承諾遭到拒絕,用戶端就會收到錯誤。

如果函式傳回的錯誤為 function.https.HttpsError 類型,用戶端會從伺服器錯誤收到 codemessagedetails 錯誤。否則,錯誤會包含訊息 INTERNAL 和代碼 INTERNAL。請參閱指南,瞭解如何在可呼叫的函式中處理錯誤

Swift

if let error = error as NSError? {
  if error.domain == FunctionsErrorDomain {
    let code = FunctionsErrorCode(rawValue: error.code)
    let message = error.localizedDescription
    let details = error.userInfo[FunctionsErrorDetailsKey]
  }
  // ...
}

Objective-C

if (error) {
  if ([error.domain isEqual:@"com.firebase.functions"]) {
    FIRFunctionsErrorCode code = error.code;
    NSString *message = error.localizedDescription;
    NSObject *details = error.userInfo[@"details"];
  }
  // ...
}

Web

var addMessage = firebase.functions().httpsCallable('addMessage');
addMessage({ text: messageText })
  .then((result) => {
    // Read result of the Cloud Function.
    var sanitizedMessage = result.data.text;
  })
  .catch((error) => {
    // Getting the Error details.
    var code = error.code;
    var message = error.message;
    var details = error.details;
    // ...
  });

Web

import { getFunctions, httpsCallable } from "firebase/functions";

const functions = getFunctions();
const addMessage = httpsCallable(functions, 'addMessage');
addMessage({ text: messageText })
  .then((result) => {
    // Read result of the Cloud Function.
    /** @type {any} */
    const data = result.data;
    const sanitizedMessage = data.text;
  })
  .catch((error) => {
    // Getting the Error details.
    const code = error.code;
    const message = error.message;
    const details = error.details;
    // ...
  });

Kotlin

addMessage(inputMessage)
    .addOnCompleteListener { task ->
        if (!task.isSuccessful) {
            val e = task.exception
            if (e is FirebaseFunctionsException) {
                val code = e.code
                val details = e.details
            }
        }
    }

Java

addMessage(inputMessage)
        .addOnCompleteListener(new OnCompleteListener<String>() {
            @Override
            public void onComplete(@NonNull Task<String> task) {
                if (!task.isSuccessful()) {
                    Exception e = task.getException();
                    if (e instanceof FirebaseFunctionsException) {
                        FirebaseFunctionsException ffe = (FirebaseFunctionsException) e;
                        FirebaseFunctionsException.Code code = ffe.getCode();
                        Object details = ffe.getDetails();
                    }
                }
            }
        });

Dart

try {
  final result =
      await FirebaseFunctions.instance.httpsCallable('addMessage').call();
} on FirebaseFunctionsException catch (error) {
  print(error.code);
  print(error.details);
  print(error.message);
}

C++

void OnAddMessageCallback(
    const firebase::Future<firebase::functions::HttpsCallableResult>& future) {
  if (future.error() != firebase::functions::kErrorNone) {
    // Function error code, will be kErrorInternal if the failure was not
    // handled properly in the function call.
    auto code = static_cast<firebase::functions::Error>(future.error());

    // Display the error in the UI.
    DisplayError(code, future.error_message());
    return;
  }

  const firebase::functions::HttpsCallableResult* result = future.result();
  firebase::Variant data = result->data();
  // This will assert if the result returned from the function wasn't a string.
  std::string message = data.string_value();
  // Display the result in the UI.
  DisplayResult(message);
}

// ...

// ...
  auto future = AddMessage(message);
  future.OnCompletion(OnAddMessageCallback);
  // ...

Unity

 addMessage(text).ContinueWith((task) => {
  if (task.IsFaulted) {
    foreach (var inner in task.Exception.InnerExceptions) {
      if (inner is FunctionsException) {
        var e = (FunctionsException) inner;
        // Function error code, will be INTERNAL if the failure
        // was not handled properly in the function call.
        var code = e.ErrorCode;
        var message = e.ErrorMessage;
      }
    }
  } else {
    string result = task.Result;
  }
});

在發布應用程式之前,請啟用 App Check,確保只有您的應用程式可以存取可呼叫的函式端點。