Resolve Firestore References

Resolve Firestore References

Firebase Firestore has a reference type while defining fields of a document which allows us to add a reference to another document via its "Document path". 
For example, I have the document animals/3OYc0QTbGOTRkhXeiW0t, with a field name having value Zebra. I reference it in the array animals, of document zoo/xmo5wX0MLUEbfFJHvKq6. I am basically storing a list of animals in a zoo, by referring the animals to the corresponding animal document in the animals collections. 
Now if I query a specific document from the zoo collection, will references to the animals be automatically resolved? Will I the get the animal names in the query result? If not, how can I achieve this? 


Solution 1:

All document queries in Firestore are shallow, meaning that you only get one document in return for each document requested.

References in a document are not automatically fetched – you will have to make subsequent queries using the references in the document to get those other documents on your own.

Same thing with documents in subcollections – they require separate queries.


Related:  Exclude testing device from Firebase Analytics logging