Use firestore in keyword to get documents by uids

Question

I read here that it is possible to use the in keyword to query firestore, where the fields of a document are matched. I want to match the uids of the documents in my collection. Is it possible to get documents having certain uids only?

I have tried .where('id', 'in', idsArray) and .where('uid', 'in', idsArray) (only certain doc uids stored in idsArray) with no avail. Please help.

So you have an array of uids and you want to query all the docs corresponding to these uid values. Is that correct? — Renaud Tarnec, Dec 17 '19 at 08:41
What is the data structure you have? Something like { id: string, uuid: string, ....}? — carlosvin, Dec 17 '19 at 09:30
@carlosvin which data structure? in my array or in firestore? — VaibhavJoshi, Dec 17 '19 at 09:39
I'm not storing uid in the document. My datastructure is something like {user_name:string, user_email:string, ...} — VaibhavJoshi, Dec 17 '19 at 12:14
Please include structures in your question because it's easier to read and adds clarity. — Jay, Dec 17 '19 at 16:43

score 1 · Accepted Answer · answered Dec 17 '19 at 09:08

1

If you want, based on an array of uids, to query all the docs corresponding to these uid values, you can use Promise.all() as follows:

const uids = ['abcde...', 'klmno...', 'wxyz...'];

const promises = uids.map(u => db.collection("yourcollection").doc(u).get());

Promise.all(promises).then(results => {

    //results is an array of DocumentSnapshots
    //use anny array method, like map or forEach      

    results.map(docSnapshot => {
            console.log(docSnapshot.data());
    });
});

answered Dec 17 '19 at 09:08

Renaud Tarnec

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So if I have 5 uids in my array, won't it make 5 different get requests? – VaibhavJoshi Dec 17 '19 at 09:16
Yes, but they will be done in parallel with `Promise.all()`. In terms of cost it will be the same cost than a query that returns 5 documents. If, for a specific reason, you absolutely need to use a query, you would need to add an extra field in your documents which holds the document's uid. – Renaud Tarnec Dec 17 '19 at 09:19

carlosvin · Answer 2 · 2019-12-17T09:16:19.040

0

Documentation says that you can't use more than 10 identifiers.

Use the in operator to combine up to 10 equality (==) clauses on the same field with a logical OR. An in query returns documents where the given field matches any of the comparison values.

https://firebase.google.com/docs/firestore/query-data/queries#in_and_array-contains-any

Other way to access to a document by identifier is:

db.collection('users').doc(uid);

edited Dec 17 '19 at 09:16

answered Dec 17 '19 at 09:07

carlosvin

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My array contains only 3-4 values. – VaibhavJoshi Dec 17 '19 at 09:15

Use firestore in keyword to get documents by uids

2 Answers2