Firestore 查询子集合 [英] Firestore query subcollections

问题描述

我以为我读到您可以使用新的 Firebase Firestore 查询子集合，但我没有看到任何示例.例如，我的 Firestore 设置如下:

I thought I read that you can query subcollections with the new Firebase Firestore, but I don't see any examples. For example I have my Firestore setup in the following way:

• 舞蹈[集合]
  • 舞蹈名称
  • 歌曲[合集]
    • 歌曲名称

    我如何才能查询查找歌曲名称 == 'X' 的所有舞蹈"

    How would I be able to query "Find all dances where songName == 'X'"

    推荐答案

    更新 2019-05-07

    今天我们发布了集合组查询，这些允许您跨子集合进行查询.

    Today we released collection group queries, and these allow you to query across subcollections.

    因此，例如在 Web SDK 中:

    So, for example in the web SDK:

    db.collectionGroup('Songs')
      .where('songName', '==', 'X')
      .get()
    

    这将匹配集合路径的最后一部分是歌曲"的任何集合中的文档.

    This would match documents in any collection where the last part of the collection path is 'Songs'.

    您最初的问题是关于找到 dances where songName == 'X'，但这仍然无法直接实现，但是，对于匹配的每首歌曲，您都可以加载其父歌曲.

    Your original question was about finding dances where songName == 'X', and this still isn't possible directly, however, for each Song that matched you can load its parent.

    原答案

    这是尚不存在的功能.它被称为集合组查询"，它允许您查询所有歌曲，而不管包含它们的舞蹈.这是我们打算支持但没有具体时间表的事情.

    This is a feature which does not yet exist. It's called a "collection group query" and would allow you query all songs regardless of which dance contained them. This is something we intend to support but don't have a concrete timeline on when it's coming.

    此时的替代结构是使歌曲成为顶级收藏，并使歌曲成为歌曲属性的一部分.

    The alternative structure at this point is to make songs a top-level collection and make which dance the song is a part of a property of the song.

    这篇关于Firestore 查询子集合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！