How to get an Array of Objects from Firestore
As per official documentation regarding arrays:
Although Cloud Firestore can store arrays,
it does not support
querying array members or updating single array elements.
If you only want to get the entire papers
array you need to iterate over a Map
like this:
Map<String, Object> map = document.getData();
for (Map.Entry<String, Object> entry : map.entrySet()) {
if (entry.getKey().equals("papers")) {
Log.d("TAG", entry.getValue().toString());
}
}
But note, even if papers
object is stored in the database as an array, entry.getValue()
returns an ArrayList
, not an array
.
Edit 13 Aug 2018:
According to the updated documentation regarding array membership, now it is possible to filter data based on array values using whereArrayContains()
method. A simple example would be:
CollectionReference citiesRef = db.collection("cities");
citiesRef.whereArrayContains("regions", "west_coast");
This query returns every city document where the regions field is an array that contains west_coast. If the array has multiple instances of the value you query on, the document is included in the results only once.