Firebase Firestore - OR query

Question

How to get data by multiple values of one field? For example, I have database with posts and I want to query for all posts where blogId is 1 or 2, sorting by timestamp.

collection("posts").whereEqualTo("blogId", "1")
.whereEqualTo("blogId", 2).orderBy("timestamp", Query.Direction.DESCENDING).limit(50)

Code above is not working :(

How to achieve this? Regards :)

Answer 1

Firestore now supports "IN" queries for this purpose.

The query would look like this:

database.collection("collectionName").where("fieldName", "in", ["fieldValue1", "fieldValue2"]);

You can have up to 10 values (fieldValueX) to check "IN" of.

---

The code OP desired would be as follows:

database.collection("posts").where("blogId", "in", ["1", "2"]); 

Answer 2

You could combine the Observables and return as one

orQuery(){

    const $one = this.afs.collection("posts", ref => ref.where("blogId","==","1")).valueChanges();
    const $two = this.afs.collection("posts", ref => ref.where("blogId","==","2")).valueChanges();

    return combineLatest($one,$two).pipe(
        map(([one, two]) => [...one, ...two])
    )
}

getOr(){
    this.orQuery().subscribe(data => console.log(data))
}

Answer 3

Firebase has listened to our requests and they have included IN query from 7 Nov, 2019. It's a kind of OR query, where you can have upto 10 OR filters.

For android:

collection("posts").whereIn("blogId", Arrays.asList("1", "2"))
.orderBy("timestamp", Query.Direction.DESCENDING).limit(50);

Firebase documentation

Answer 4

OR operator is not accepted in firebase firestore:

Cloud Firestore provides limited support for logical OR queries. The in, and array-contains-any operators support a logical OR of up to 10 equality (==) or array-contains conditions on a single field. For other cases, create a separate query for each OR condition and merge the query results in your app.

Queries in Cloud Firestore, Query limitations

Normally using firebase syntax you can call two collections:

const res1 = async collection("posts", ref => ref.where('blogId', '==', 1).get();
const res2 = async collection("posts", ref => ref.where('blogId', '==', 2).get();

and you can merge the results before serving to the view.

But in this case where you have blogIds you can use this syntax: collection("posts").orderBy('blogId').startAt(1).endAt(2);

e.d

Answer 5

I couldn't find any documentation for the ability to OR together where conditions. But you can rephrase your requirement on the blogId as follows:

WHERE blogId > 0 AND blogId < 3

Try this code:

collection("posts")
.where("blogId", ">", "0")
.where("blogId", "<", "3")
.orderBy("timestamp", Query.Direction.DESCENDING)
.limit(50)

Answer 6

Firestore has no OR queries. They way you'd do that is by running two queries and splicing them.

You could for example:

const search = ( key, value ) =>  collection( 'users' ).where( key, '==', value ).get().then( doc => doc.data() )

Promise.all( [ search( 'name', 'John' ), search( 'name', 'Johnny' ) ] )
.then( ( [ one, two ] ) => one.concat( two ) )
.then( allResults => dothings() )

Answer 7

For Android, I am using OR query like this.

List<String> values = new ArrayList<>();
    values.add("Value 1");
    values.add("Value 2");

and then use the .whereIn query like this.

db.collection("collectionName")
            .whereIn("fieldName", values)   // where values is the list we created
            .get()
            .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull Task<QuerySnapshot> task) {

                    if (task.isSuccessful()) {

                      // Do your stuff

                    }

                }
            });

Answer 8

Try this

collection("posts").start("blogId", "1")
.end("blogId", 2).orderBy("timestamp", Query.Direction.DESCENDING).limit(50)

Answer 9

You can use De Morgaan's laws to rewrite an AND query as an OR query.