二阶通过查询在Firestore中不执行任何操作（react-native-firebase）

Question

EDIT So after reviewing this problem with firebase developer this is working by design and there is no actual way to acheive this. Offical response from firestore dev:

Admittedly certain kinds of queries are difficult, if not feasible, when working with Firestore's NoSQL design. If the lack of such capabilities is considered a deal-breaker for your use-case, then it's likely that Firestore may not be the right database solution for you.

If you're desperate to achieve something similar then possibly this solution will work for you: https://firebase.google.com/docs/firestore/solutions/arrays#solution_a_map_of_values .

If not there is always AWS

===========================================================================

I'm noticing that the second orderBy query option does nothing to the data that is returned. Consider the following query:

firebase.firestore()
  .collection('posts')
  .orderBy('date', 'desc')
  .where('date', '>', new Date(1529802276644))
  .orderBy('rating', 'desc')
  .limit(size)

This query is intending to order posts by the date field, then filter then for the last two days, then order them by rating .

This query is currently returning 3 posts within two days, however is not sorting by rating. The results I receive are:

[
  {date: 3 hours ago, rating: 1},
  {date: 5 hours ago, rating: -1},
  {date: 9 hours ago, rating: 0},
]

And if I conduct the same query with the last orderBy removed, I actually get the exact same results:

firebase.firestore()
  .collection('posts')
  .orderBy('date', 'desc')
  .where('date', '>', new Date(1529802276644))
  .limit(size)

produces:

[
  {date: 3 hours ago, rating: 1},
  {date: 5 hours ago, rating: -1},
  {date: 9 hours ago, rating: 0},
]

I currently have an enabled index over posts. I'm fairly certain the index is correct because I was previously getting an error about a missing index before this and then fixed it with this index:

posts |  date DESC rating DESC   |    enabled

I'm pretty sure the problem lies with firebase and not with the library I'm using react-native-firebase. The firebase firestore SDK I am using is on 5.0.4 I believe

EDIT Here is how I actually use the code within my react-native project:

const episodeRef = firebase.firestore().collection('posts');
const baseRequest = episodeRef.orderBy('date', 'desc').where('date', '>', new Date(1529802276644)).orderBy('rating', 'desc').limit(25)
const documentSnapshots = await baseRequest.get()
console.log('documentSnapshots', documentSnapshots);

The console.log prints out a valid querysnapshot, and the _query field roughly looks like this:

_fieldFilters:{
    fieldPath:{
        string:"date",
        type:"string"
    },
    operator:"GREATER_THAN",
    value:{
        type:"date",
        value:1529802276644
    },
}
_fieldOrders:{
    0:{
        direction:"DESCENDING",
        fieldPath: {
            string:"date",
            type:"string"
        },
    }
    1:{
        direction:"DESCENDING"
        fieldPath:{
            string:"rating",
            type:"string"
        }
    }
}

(bad printing due to copying)

Answer 1

I'm not certain this is the cause, but in Firebase Realtime Database it is a common mistake, so it's worth a short here too.

When you convert the QuerySnapshot documentSnapshots to a string, it loses any information on the order of the data.

Instead loop over the results with QuerySnapshot.forEach() to ensure you maintain the order you requested the data in:

const documentSnapshots = await baseRequest.get()
documentSnapshots.forEach(document => {
  console.log('document', document);
});

If that works, this probably also works:

const documentSnapshots = await baseRequest.get()
console.log('document', documentSnapshots.docs());