Firestore 触发器

您可以将 Cloud Run 函数配置为由 Firestore 数据库中的事件触发。触发后,您的函数可以通过 Firestore API 和客户端库读取和更新 Firestore 数据库,以便对这些事件做出响应。

在一个典型的生命周期中,Firestore 函数会执行以下操作:

  1. 等待特定文档发生更改。

  2. 在事件发生时触发并执行相应的任务。

  3. 接收包含受影响文档快照的数据对象。对于 writeupdate 事件,该数据对象包含代表触发事件前后的文档状态的快照。

事件类型

Firestore 支持 createupdatedeletewrite 事件。write 事件包含对某个文档所做的所有修改。

事件类型 触发器
google.cloud.firestore.document.v1.created(默认) 首次写入某个文档时触发。
google.cloud.firestore.document.v1.updated 当某文档已存在并且其任何值发生了更改时触发。
google.cloud.firestore.document.v1.deleted 当文档的数据被删除时触发。
google.cloud.firestore.document.v1.written 在创建、更新或删除某个文档时触发。

在触发器中,通配符是使用大括号编写的,如下所示: "projects/YOUR_PROJECT_ID/databases/(default)/documents/collection/{document_wildcard}"

指定文档路径

如需触发您的函数,请指定要侦听的文档路径。文档路径必须与函数位于同一 Google Cloud 项目中。

以下是一些有效和无效的文档路径示例:

  • users/marie:有效的触发器。监控单个文档 (/users/marie)。

  • users/{username}:有效的触发器。监控所有用户文档。通配符用于监控集合中的所有文档。

  • users/{username}/addresses无效的触发器。该路径指向的是子集合 addresses,而不是某个文档。

  • users/{username}/addresses/home:有效的触发器。监控所有用户的家庭住址文档。

  • users/{username}/addresses/{addressId}:有效的触发器。监控所有地址文档。

  • users/{user=**}:有效的触发器。监控所有用户文档以及每个用户文档下子集合中的任何文档,例如 /users/userID/address/home/users/userID/phone/work

通配符和参数

如果您不知道要监控的特定文档,请使用 {wildcard} 代替文档 ID:

  • users/{username} 侦听所有用户文档的更改。

在此示例中,如果 users 中的任何文档的任何字段发生更改,都会与一个名为 {username} 的通配符相匹配。

如果 users 中的某个文档有多个子集合,并且这些子集合中一个文档内的某字段发生了更改,那么不会触发 {username} 通配符。 如果您的目标是同时也响应子集合中的事件,请使用多段通配符 {username=**}

通配符匹配项会从文档路径中提取出来。 您可以定义任意多个通配符,以替代明确指定的集合或文档 ID。最多可以使用一个多段通配符,例如 {username=**}

事件结构

当发生如下所示的事件时,此触发器会调用您的函数:

{
    "oldValue": { // Update and Delete operations only
        A Document object containing a pre-operation document snapshot
    },
    "updateMask": { // Update operations only
        A DocumentMask object that lists changed fields.
    },
    "value": {
        // A Document object containing a post-operation document snapshot
    }
}

每个 Document 对象都包含一个或多个 Value 对象。如需查看类型参考信息,请参阅 Value 文档。如果您使用类型化语言(例如 Go)编写函数,此方法特别有用。

示例

以下示例演示了如何编写响应 Firestore 触发器的函数。

准备工作

  1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.
  2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Go to project selector

  3. Make sure that billing is enabled for your Google Cloud project.

  4. Enable the Cloud Functions, Cloud Build, Artifact Registry, Eventarc, Logging, Pub/Sub, and Cloud Run APIs.

    Enable the APIs

  5. Install the Google Cloud CLI.
  6. To initialize the gcloud CLI, run the following command:

    gcloud init
  7. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Go to project selector

  8. Make sure that billing is enabled for your Google Cloud project.

  9. Enable the Cloud Functions, Cloud Build, Artifact Registry, Eventarc, Logging, Pub/Sub, and Cloud Run APIs.

    Enable the APIs

  10. Install the Google Cloud CLI.
  11. To initialize the gcloud CLI, run the following command:

    gcloud init
  12. 如果您已经安装 gcloud CLI,请运行以下命令进行更新:

    gcloud components update
  13. 准备开发环境。

设置您的 Firestore 数据库

您需要一个 Firestore 数据库来测试本文档中的示例。您必须先设置好 Cloud Firestore 数据库,然后再部署函数。如果您还没有 Firestore 数据库,请按如下方式创建一个:

  1. 进入 Firestore 数据页面

  2. 点击选择原生模式

  3. 选择数据库位于的区域(位置)。一旦选择便无法更改。

  4. 点击创建数据库

Firestore 数据模型由包含文档的集合组成。每个文档包含一组键值对。

当您对指定集合内的文档进行更改时,会触发您在本教程中创建的函数。

示例 1:Hello Firestore 函数

以下示例 Cloud Run 函数会输出触发 Firestore 事件的字段:

Node.js

使用 protobufjs 解码事件数据。在源代码中添加 google.events.cloud.firestore.v1 data.proto

/**
 * Cloud Event Function triggered by a change to a Firestore document.
 */
const functions = require('@google-cloud/functions-framework');
const protobuf = require('protobufjs');

functions.cloudEvent('helloFirestore', async cloudEvent => {
  console.log(`Function triggered by event on: ${cloudEvent.source}`);
  console.log(`Event type: ${cloudEvent.type}`);

  console.log('Loading protos...');
  const root = await protobuf.load('data.proto');
  const DocumentEventData = root.lookupType(
    'google.events.cloud.firestore.v1.DocumentEventData'
  );

  console.log('Decoding data...');
  const firestoreReceived = DocumentEventData.decode(cloudEvent.data);

  console.log('\nOld value:');
  console.log(JSON.stringify(firestoreReceived.oldValue, null, 2));

  console.log('\nNew value:');
  console.log(JSON.stringify(firestoreReceived.value, null, 2));
});

Python

from cloudevents.http import CloudEvent
import functions_framework
from google.events.cloud import firestore


@functions_framework.cloud_event
def hello_firestore(cloud_event: CloudEvent) -> None:
    """Triggers by a change to a Firestore document.

    Args:
        cloud_event: cloud event with information on the firestore event trigger
    """
    firestore_payload = firestore.DocumentEventData()
    firestore_payload._pb.ParseFromString(cloud_event.data)

    print(f"Function triggered by change to: {cloud_event['source']}")

    print("\nOld value:")
    print(firestore_payload.old_value)

    print("\nNew value:")
    print(firestore_payload.value)

Go


// Package hellofirestore contains a Cloud Event Function triggered by a Cloud Firestore event.
package hellofirestore

import (
	"context"
	"fmt"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
	"github.com/googleapis/google-cloudevents-go/cloud/firestoredata"
	"google.golang.org/protobuf/proto"
)

func init() {
	functions.CloudEvent("helloFirestore", HelloFirestore)
}

// HelloFirestore is triggered by a change to a Firestore document.
func HelloFirestore(ctx context.Context, event event.Event) error {
	var data firestoredata.DocumentEventData

	// If you omit `DiscardUnknown`, protojson.Unmarshal returns an error
	// when encountering a new or unknown field.
	options := proto.UnmarshalOptions{
		DiscardUnknown: true,
	}
	err := options.Unmarshal(event.Data(), &data)

	if err != nil {
		return fmt.Errorf("proto.Unmarshal: %w", err)
	}

	fmt.Printf("Function triggered by change to: %v\n", event.Source())
	fmt.Printf("Old value: %+v\n", data.GetOldValue())
	fmt.Printf("New value: %+v\n", data.GetValue())
	return nil
}

Java

import com.google.cloud.functions.CloudEventsFunction;
import com.google.events.cloud.firestore.v1.DocumentEventData;
import com.google.protobuf.InvalidProtocolBufferException;
import io.cloudevents.CloudEvent;
import java.util.logging.Logger;

public class FirebaseFirestore implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(FirebaseFirestore.class.getName());

  @Override
  public void accept(CloudEvent event) throws InvalidProtocolBufferException {
    DocumentEventData firestoreEventData = DocumentEventData
        .parseFrom(event.getData().toBytes());

    logger.info("Function triggered by event on: " + event.getSource());
    logger.info("Event type: " + event.getType());

    logger.info("Old value:");
    logger.info(firestoreEventData.getOldValue().toString());

    logger.info("New value:");
    logger.info(firestoreEventData.getValue().toString());
  }
}

C#

using CloudNative.CloudEvents;
using Google.Cloud.Functions.Framework;
using Google.Events.Protobuf.Cloud.Firestore.V1;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace FirebaseFirestore;

public class Function : ICloudEventFunction<DocumentEventData>
{
    private readonly ILogger _logger;

    public Function(ILogger<Function> logger) =>
        _logger = logger;

    public Task HandleAsync(CloudEvent cloudEvent, DocumentEventData data, CancellationToken cancellationToken)
    {
        _logger.LogInformation("Function triggered by event on {subject}", cloudEvent.Subject);
        _logger.LogInformation("Event type: {type}", cloudEvent.Type);
        MaybeLogDocument("Old value", data.OldValue);
        MaybeLogDocument("New value", data.Value);

        // In this example, we don't need to perform any asynchronous operations, so the
        // method doesn't need to be declared async.
        return Task.CompletedTask;
    }

    /// <summary>
    /// Logs the names and values of the fields in a document in a very simplistic way.
    /// </summary>
    private void MaybeLogDocument(string message, Document document)
    {
        if (document is null)
        {
            return;
        }

        // ConvertFields converts the Firestore representation into a .NET-friendly
        // representation.
        IReadOnlyDictionary<string, object> fields = document.ConvertFields();
        var fieldNamesAndTypes = fields
            .OrderBy(pair => pair.Key)
            .Select(pair => $"{pair.Key}: {pair.Value}");
        _logger.LogInformation(message + ": {fields}", string.Join(", ", fieldNamesAndTypes));
    }
}

部署 Hello Firestore 函数

  1. 设置 Firestore 数据库(如果您尚未这样做)。

  2. 如需使用 Firestore 触发器部署 Hello Firestore 函数,请在包含示例代码(如果是 Java,则为 pom.xml 文件)的目录中运行以下命令:

    gcloud functions deploy FUNCTION_NAME \
    --gen2 \
    --runtime=RUNTIME \
    --region=REGION \
    --trigger-location=TRIGGER REGION \
    --source=. \
    --entry-point=ENTRY_POINT \
    --trigger-event-filters=type=google.cloud.firestore.document.v1.written \
    --trigger-event-filters=database='(default)' \
    --trigger-event-filters-path-pattern=document='users/{username}'

    替换以下内容:

    • FUNCTION_NAME:已部署函数的名称。
    • RUNTIME:您的函数使用的语言运行时。
    • REGION:要在其中部署函数的区域。
    • TRIGGER_REGION:触发器的位置,必须与 Firestore 数据库的区域相同。
    • ENTRY_POINT:源代码中函数的入口点。这是在您的函数运行时执行的代码。

    按原样使用其他字段:

    • --trigger-event-filters=type=google.cloud.firestore.document.v1.written 指定根据 google.cloud.firestore.document.v1.written 事件类型创建、更新或删除文档时触发函数。
    • --trigger-event-filters=database='(default)' 指定 Firebase 数据库。对于默认数据库名称,请使用 (default)
    • --trigger-event-filters-path-pattern=document='users/{username}' 提供受监控文档的路径模式,应监控这些文档是否发生相关改变。此路径模式声明 users 集合中的所有文档都应被监控。如需了解详情,请参阅了解路径模式

测试 Hello Firestore 函数

如需测试 Hello Firestore 函数,请在 Firestore 数据库中设置一个名为 users 的集合:

  1. “Firestore 数据”页面上,点击开始使用集合

  2. 指定 users 作为集合 ID。

  3. 如需开始添加集合的第一个文档,请在为其添加首个文档下接受自动生成的文档 ID

  4. 为文档至少添加一个字段,并指定名称和值。在此示例中,名称为“username”,值为“rowan”:

    展示如何创建 Firestore 集合的屏幕截图

  5. 完成之后,点击保存

    此操作会创建一个新文档,从而触发您的函数。

  6. 如需确认您的函数已触发,请在 Google Cloud 控制台 Cloud Run functions 概览页面中点击该函数的链接名称,以打开函数详情页面。

  7. 打开日志标签页,然后查找此字符串:

Function triggered by change to: //firestore.googleapis.com/projects/your-project-id/databases/(default)'

示例 2:“转换为大写”函数

以下示例会检索用户添加的值,将该位置的字符串转换为大写,然后将该值替换为该大写字符串:

Node.js

使用 protobufjs 解码事件数据。在源代码中添加 google.events.cloud.firestore.v1 data.proto

const functions = require('@google-cloud/functions-framework');
const Firestore = require('@google-cloud/firestore');
const protobuf = require('protobufjs');

const firestore = new Firestore({
  projectId: process.env.GOOGLE_CLOUD_PROJECT,
});

// Converts strings added to /messages/{pushId}/original to uppercase
functions.cloudEvent('makeUpperCase', async cloudEvent => {
  console.log('Loading protos...');
  const root = await protobuf.load('data.proto');
  const DocumentEventData = root.lookupType(
    'google.events.cloud.firestore.v1.DocumentEventData'
  );

  console.log('Decoding data...');
  const firestoreReceived = DocumentEventData.decode(cloudEvent.data);

  const resource = firestoreReceived.value.name;
  const affectedDoc = firestore.doc(resource.split('/documents/')[1]);

  const curValue = firestoreReceived.value.fields.original.stringValue;
  const newValue = curValue.toUpperCase();

  if (curValue === newValue) {
    // Value is already upper-case
    // Don't perform a(nother) write to avoid infinite loops
    console.log('Value is already upper-case.');
    return;
  }

  console.log(`Replacing value: ${curValue} --> ${newValue}`);
  affectedDoc.set({
    original: newValue,
  });
});

Python

from cloudevents.http import CloudEvent
import functions_framework
from google.cloud import firestore
from google.events.cloud import firestore as firestoredata

client = firestore.Client()


# Converts strings added to /messages/{pushId}/original to uppercase
@functions_framework.cloud_event
def make_upper_case(cloud_event: CloudEvent) -> None:
    firestore_payload = firestoredata.DocumentEventData()
    firestore_payload._pb.ParseFromString(cloud_event.data)

    path_parts = firestore_payload.value.name.split("/")
    separator_idx = path_parts.index("documents")
    collection_path = path_parts[separator_idx + 1]
    document_path = "/".join(path_parts[(separator_idx + 2) :])

    print(f"Collection path: {collection_path}")
    print(f"Document path: {document_path}")

    affected_doc = client.collection(collection_path).document(document_path)

    cur_value = firestore_payload.value.fields["original"].string_value
    new_value = cur_value.upper()

    if cur_value != new_value:
        print(f"Replacing value: {cur_value} --> {new_value}")
        affected_doc.set({"original": new_value})
    else:
        # Value is already upper-case
        # Don't perform a second write (which can trigger an infinite loop)
        print("Value is already upper-case.")

Go


// Package upper contains a Firestore Cloud Function.
package upper

import (
	"context"
	"errors"
	"fmt"
	"log"
	"os"
	"strings"

	"cloud.google.com/go/firestore"
	firebase "firebase.google.com/go/v4"
	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
	"github.com/googleapis/google-cloudevents-go/cloud/firestoredata"
	"google.golang.org/protobuf/proto"
)

// set the GOOGLE_CLOUD_PROJECT environment variable when deploying.
var projectID = os.Getenv("GOOGLE_CLOUD_PROJECT")

// client is a Firestore client, reused between function invocations.
var client *firestore.Client

func init() {
	// Use the application default credentials.
	conf := &firebase.Config{ProjectID: projectID}

	// Use context.Background() because the app/client should persist across
	// invocations.
	ctx := context.Background()

	app, err := firebase.NewApp(ctx, conf)
	if err != nil {
		log.Fatalf("firebase.NewApp: %v", err)
	}

	client, err = app.Firestore(ctx)
	if err != nil {
		log.Fatalf("app.Firestore: %v", err)
	}

	// Register cloud event function
	functions.CloudEvent("MakeUpperCase", MakeUpperCase)
}

// MakeUpperCase is triggered by a change to a Firestore document. It updates
// the `original` value of the document to upper case.
func MakeUpperCase(ctx context.Context, e event.Event) error {
	var data firestoredata.DocumentEventData

	// If you omit `DiscardUnknown`, protojson.Unmarshal returns an error
	// when encountering a new or unknown field.
	options := proto.UnmarshalOptions{
		DiscardUnknown: true,
	}
	err := options.Unmarshal(e.Data(), &data)

	if err != nil {
		return fmt.Errorf("proto.Unmarshal: %w", err)
	}

	if data.GetValue() == nil {
		return errors.New("Invalid message: 'Value' not present")
	}

	fullPath := strings.Split(data.GetValue().GetName(), "/documents/")[1]
	pathParts := strings.Split(fullPath, "/")
	collection := pathParts[0]
	doc := strings.Join(pathParts[1:], "/")

	var originalStringValue string
	if v, ok := data.GetValue().GetFields()["original"]; ok {
		originalStringValue = v.GetStringValue()
	} else {
		return errors.New("Document did not contain field \"original\"")
	}

	newValue := strings.ToUpper(originalStringValue)
	if originalStringValue == newValue {
		log.Printf("%q is already upper case: skipping", originalStringValue)
		return nil
	}
	log.Printf("Replacing value: %q -> %q", originalStringValue, newValue)

	newDocumentEntry := map[string]string{"original": newValue}
	_, err = client.Collection(collection).Doc(doc).Set(ctx, newDocumentEntry)
	if err != nil {
		return fmt.Errorf("Set: %w", err)
	}
	return nil
}

Java

import com.google.cloud.firestore.Firestore;
import com.google.cloud.firestore.FirestoreOptions;
import com.google.cloud.firestore.SetOptions;
import com.google.cloud.functions.CloudEventsFunction;
import com.google.events.cloud.firestore.v1.DocumentEventData;
import com.google.events.cloud.firestore.v1.Value;
import com.google.protobuf.InvalidProtocolBufferException;
import io.cloudevents.CloudEvent;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.logging.Logger;

public class FirebaseFirestoreReactive implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(FirebaseFirestoreReactive.class.getName());
  private final Firestore firestore;

  private static final String FIELD_KEY = "original";
  private static final String APPLICATION_PROTOBUF = "application/protobuf";

  public FirebaseFirestoreReactive() {
    this(FirestoreOptions.getDefaultInstance().getService());
  }

  public FirebaseFirestoreReactive(Firestore firestore) {
    this.firestore = firestore;
  }

  @Override
  public void accept(CloudEvent event)
      throws InvalidProtocolBufferException, InterruptedException, ExecutionException {
    if (event.getData() == null) {
      logger.warning("No data found in event!");
      return;
    }

    if (!event.getDataContentType().equals(APPLICATION_PROTOBUF)) {
      logger.warning(String.format("Found unexpected content type %s, expected %s",
          event.getDataContentType(),
          APPLICATION_PROTOBUF));
      return;
    }

    DocumentEventData firestoreEventData = DocumentEventData
        .parseFrom(event.getData().toBytes());

    // Get the fields from the post-operation document snapshot
    // https://firebase.google.com/docs/firestore/reference/rest/v1/projects.databases.documents#Document
    Map<String, Value> fields = firestoreEventData.getValue().getFieldsMap();
    if (!fields.containsKey(FIELD_KEY)) {
      logger.warning("Document does not contain original field");
      return;
    }
    String currValue = fields.get(FIELD_KEY).getStringValue();
    String newValue = currValue.toUpperCase();

    if (currValue.equals(newValue)) {
      logger.info("Value is already upper-case");
      return;
    }

    // Retrieve the document name from the resource path:
    // projects/{project_id}/databases/{database_id}/documents/{document_path}
    String affectedDoc = firestoreEventData.getValue()
        .getName()
        .split("/documents/")[1]
        .replace("\"", "");

    logger.info(String.format("Replacing values: %s --> %s", currValue, newValue));

    // Wait for the async call to complete
    this.firestore
        .document(affectedDoc)
        .set(Map.of(FIELD_KEY, newValue), SetOptions.merge())
        .get();
  }
}

C#

using CloudNative.CloudEvents;
using Google.Cloud.Firestore;
using Google.Cloud.Functions.Framework;
using Google.Cloud.Functions.Hosting;
using Google.Events.Protobuf.Cloud.Firestore.V1;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace FirestoreReactive;

public class Startup : FunctionsStartup
{
    public override void ConfigureServices(WebHostBuilderContext context, IServiceCollection services) =>
        services.AddSingleton(FirestoreDb.Create());
}

// Register the startup class to provide the Firestore dependency.
[FunctionsStartup(typeof(Startup))]
public class Function : ICloudEventFunction<DocumentEventData>
{
    private readonly ILogger _logger;
    private readonly FirestoreDb _firestoreDb;

    public Function(ILogger<Function> logger, FirestoreDb firestoreDb) =>
        (_logger, _firestoreDb) = (logger, firestoreDb);

    public async Task HandleAsync(CloudEvent cloudEvent, DocumentEventData data, CancellationToken cancellationToken)
    {
        // Get the recently-written value. This expression will result in a null value
        // if any of the following is true:
        // - The event doesn't contain a "new" document
        // - The value doesn't contain a field called "original"
        // - The "original" field isn't a string
        string currentValue = data.Value?.ConvertFields().GetValueOrDefault("original") as string;
        if (currentValue is null)
        {
            _logger.LogWarning($"Event did not contain a suitable document");
            return;
        }

        string newValue = currentValue.ToUpperInvariant();
        if (newValue == currentValue)
        {
            _logger.LogInformation("Value is already upper-cased; no replacement necessary");
            return;
        }

        // The CloudEvent subject is "documents/x/y/...".
        // The Firestore SDK FirestoreDb.Document method expects a reference relative to
        // "documents" (so just the "x/y/..." part). This may be simplified over time.
        if (cloudEvent.Subject is null || !cloudEvent.Subject.StartsWith("documents/"))
        {
            _logger.LogWarning("CloudEvent subject is not a document reference.");
            return;
        }
        string documentPath = cloudEvent.Subject.Substring("documents/".Length);

        _logger.LogInformation("Replacing '{current}' with '{new}' in '{path}'", currentValue, newValue, documentPath);
        await _firestoreDb.Document(documentPath).UpdateAsync("original", newValue, cancellationToken: cancellationToken);
    }
}

部署“转换为大写”函数

  1. 设置 Firestore 数据库(如果您尚未这样做)。

  2. 使用以下命令部署一个由文档 companies/{CompanyId} 上的写入事件触发的函数:

    gcloud functions deploy FUNCTION_NAME \
    --gen2 \
    --runtime=RUNTIME \
    --trigger-location=TRIGGER REGION \
    --region=REGION \
    --source=. \
    --entry-point=ENTRY_POINT \
    --set-env-vars GOOGLE_CLOUD_PROJECT=PROJECT_ID \
    --trigger-event-filters=type=google.cloud.firestore.document.v1.written \
    --trigger-event-filters=database='(default)' \
    --trigger-event-filters-path-pattern=document='messages/{pushId}'

    替换以下内容:

    • FUNCTION_NAME:已部署函数的名称。
    • RUNTIME:您的函数使用的语言运行时。
    • REGION:要在其中部署函数的区域。
    • TRIGGER_REGION:触发器的位置,必须与 Firestore 数据库的区域相同。
    • ENTRY_POINT:源代码中函数的入口点。这是在您的函数运行时执行的代码。
    • PROJECT_ID:项目的唯一标识符。

    按原样使用其他字段:

    • --trigger-event-filters=type=google.cloud.firestore.document.v1.written 指定根据 google.cloud.firestore.document.v1.written 事件类型创建、更新或删除文档时触发函数。
    • --trigger-event-filters=database='(default)' 指定 Firestore 数据库。对于默认数据库名称,请使用 (default)
    • --trigger-event-filters-path-pattern=document='messages/{pushId}' 提供受监控文档的路径模式,应监控这些文档是否发生相关改变。此路径模式声明 messages 集合中的所有文档都应被监控。如需了解详情,请参阅了解路径模式

测试“转换为大写”函数

如需测试刚刚部署的转换为大写函数,请在 Firestore 数据库中设置一个名为 messages 的集合:

  1. 进入 Firestore 数据页面

  2. 点击开始使用集合

  3. 指定 messages 作为集合 ID。

  4. 如需开始添加集合的第一个文档,请在为其添加首个文档下接受自动生成的文档 ID

  5. 如需触发已部署的函数,请添加一个文档,其字段名称为“original”且字段值为小写字母单词,例如:

    展示如何创建 Firestore 集合的屏幕截图

  6. 保存文档时,您可以看到值字段中的小写字词转换为大写字词。

    如果您随后修改字段值以包含小写字母,则会再次触发该函数,并将所有小写字母转换为大写字母。

限制

  • 无法保证顺序。快速更改可能会以意想不到的顺序触发函数调用。
  • 事件至少会被传送一次,但单个事件可能会导致多次调用函数。应该避免依赖“正好一次”机制,并编写幂等函数
  • 一个触发器与单一数据库相关联。您无法创建与多个数据库匹配的触发器。
  • 删除数据库不会自动删除该数据库的任何触发器。触发器会停止传送事件,但会继续存在,直到您删除触发器