我的目标是做一个交易来删除一个用户和他的所有文档（用户和广告集）。
当我删除一个用户时，我想在广告集合中用“deleted”：true更新他的广告。
所以我写了如下代码：

/// Marks user as deleted
  Future<void> storeMarkAsDeleted() async {
    final fs = FirebaseFirestore.instance;
    final writeBatch = fs.batch();

    // = Open a transaction to perform both operations
    return fs.runTransaction((t) async {
      final user = await t.get(fs.collection(collectionName).doc(id));

      /// Reads the ad document
      final ads = await fs
          .collection(collectionName)
          .where("ownerId", isEqualTo: id)
          .get();

      // Mark user as deleted
      t.update(user.reference, {
        "deleted": true,
      });

      // Update all docs
      for (final doc in ads.docs) {
     
        writeBatch.update(doc.reference, {
          "clearedForSale": false,
          "deleted": true,
        });
      }
      // unless commit is called, nothing happens.
      writeBatch.commit();
    });
  }

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但我不确定这是否是正确的做法。