如何从 Android 中删除 Firestore 集合

Question

问题

我正在寻找一种临时解决方案来从客户端删除集合以进行概念验证。我最终会按照建议将其重构到服务器上。

我正在添加删除特定 Firestore 用户的所有帐户信息的功能，包括他们在应用中保存的内容集合。根据Firestore documentation，客户端没有规定的方法可以这样做，因为建议在服务器上处理。

Answer 1

要从 Cloud Firestore 数据库中删除整个集合或子集合，您需要检索该集合或子集合中的所有文档并将其删除。

如果您有较大的集合，您可能希望以较小的批次删除文档以避免内存不足错误。所以你应该重复这个过程，直到你删除了整个集合或子集合。

即使 Firebase 团队不推荐删除操作，因为它具有负面的安全性和性能影响，您仍然可以执行此操作，但仅限于 small collections。如果您需要删除整个网络集合，请仅从受信任的服务器环境中执行此操作。

对于 Kotlin，请使用以下函数：

private fun deleteCollection(collection: CollectionReference, executor: Executor) {
    Tasks.call(executor) {
        val batchSize = 10
        var query = collection.orderBy(FieldPath.documentId()).limit(batchSize.toLong())
        var deleted = deleteQueryBatch(query)

        while (deleted.size >= batchSize) {
            val last = deleted[deleted.size - 1]
            query = collection.orderBy(FieldPath.documentId()).startAfter(last.id).limit(batchSize.toLong())

            deleted = deleteQueryBatch(query)
        }

        null
    }
}

@WorkerThread
@Throws(Exception::class)
private fun deleteQueryBatch(query: Query): List<DocumentSnapshot> {
    val querySnapshot = Tasks.await(query.get())

    val batch = query.firestore.batch()
    for (snapshot in querySnapshot) {
        batch.delete(snapshot.reference)
    }
    Tasks.await(batch.commit())

    return querySnapshot.documents
}

Answer 2

更新的解决方案

Firebase 团队的 Delete Collections and Subcollections 记录解决方案更加可靠和安全，因为它是在客户端外部的云函数中实施的。我已经相应地重构了我的解决方案。

/**
* Initiate a recursive delete of documents at a given path.
*
* This delete is NOT an atomic operation and it's possible
* that it may fail after only deleting some documents.
*
* @param {string} data.path the document or collection path to delete.
*/

exports.deleteUser = () => functions.runWith({timeoutSeconds: 540, memory: '2GB'})
   .https.onCall((data, context) => {
    if (context.auth.uid !== data.userId)
      throw new functions.https.HttpsError(
        'permission-denied','Must be an administrative user to initiate delete.');
    const path = data.path;
    console.log(`User ${context.auth.uid} has requested to delete path ${path}`);

    return firebase_tools.firestore.delete(path, {
      project: process.env.GCLOUD_PROJECT,
      recursive: true,
      yes: true,
      token: functions.config().fb.token
    }).then(() => { return { path: path }; });
});

旧解决方案（在客户端执行）

传递给方法的是用户集合的引用和要处理的批量大小。

fun deleteCollection(collection: CollectionReference, batchSize: Int) {
    try {
        // Retrieve a small batch of documents to avoid out-of-memory errors/
        var deleted = 0
        collection
                .limit(batchSize.toLong())
                .get()
                .addOnCompleteListener {
                    for (document in it.result.documents) {
                        document.getReference().delete()
                        ++deleted
                    }
                    if (deleted >= batchSize) {
                        // retrieve and delete another batch
                        deleteCollection(collection, batchSize)
                    }
                }
    } catch (e: Exception) {
        System.err.println("Error deleting collection : " + e.message)
    }
}