要删除分类广告在我的应用程序中，我有一个两步的过程，其中包括：
1.在集合中创建新文档，同时更新另一个文档;
1.通过更新“已删除”来更新广告：true字段。
我希望它是同一事务的一部分，是原子的。
我知道一个事务可以在get上运行多次，而这些都必须在开始时：这让我很困惑，因为我不会有新创建的文档的多个副本。
因此，我将感谢您的帮助，告诉我如何做到这一点？
我现有的代码如下：

// Deletes the ad or throw an error if it does not exist or if an error occured
  Future<void> transactionStoreDelete() async {
    final fs = FirebaseFirestore.instance;

    // == Move assets to to-be-deleted collections for future actual removal
    // from our servers and services
    // Note that if we do not succeed at moving the video assets to the
    // collection, there would be a yet-to-be-delvelopped server worker that
    // find unreferenced video and stream assets that will remove them from the
    // cloud and our services.
    try {
      await storeMarkVideoAndStreamToBeDeleted();

      await FirebaseFirestore.instance.runTransaction((t) async {
        /// Reads the ad document
        final doc = await t.get(fs.collection("ads").doc(id));

        if (doc.exists) {
          t.delete(doc.reference);
        }
      });
    } catch (e) {
      debugPrint(
          "Could not move video assets to to-be-deleted collections: $e");
    }
  }

字符串
其中storeMarkVideoAndStreamToBeDeleted如下：

/// Clean up video assets byt doing the following:
  /// 1) Move the video and video stream to the to-be-deleted related collections;
  /// 2) Nullify [videoUrl] and [stream] in the current ad instance;
  /// 3) Update the ad in the collection.
  ///
  Future<void> storeMarkVideoAndStreamToBeDeleted() async {
    if (videoUrl != null) {
      try {
        // == Create record set in to be delted video
        await FirebaseFirestore.instance.collection("toBeDeletedVideos").add({
          ...trackingInformation,
          "url": videoUrl!,
        });
      } catch (e) {
        debugPrint("Could not move the video to be deleted: $e");
      }
    }

    if (stream != null) {
      try {
        // == Create record set in  to be deleted stream
        await FirebaseFirestore.instance.collection("toBeDeletedStreams").add({
          ...trackingInformation,
          "streamId": stream!.id,
        });
      } catch (e) {
        debugPrint("Could not move the stream video to be deleted: $e");
      }
    }

    // == Now erase reference to them
    return FirebaseFirestore.instance
        .collection("ads")
        .doc(id)
        .update({
      "videoUrl": null,
      "stream": null,
    });
  }

型
[更新]在阅读评论后，试着澄清问题。
[更新2]写了收藏品的名称以供澄清。
[更新3]我想实现的伪代码中的工作流程：

t = openTheTransaction()

ad = 
adsCollection.getTheAdDocumentReferenceFrom(t)

t.create(toBeDeletedVideosCollection.createDocumentWith(ad))

t.create(toBeDeletedStreamsCollection.createDocumentWith(ad))

t.update(ad, {deleted:true})

t.commit()

型
希望对你有帮助。