Always getting whole document while any changes found on Firestore. How to get data that are newly updated only?
This is my data:
I need msg and sendby in order of object(for eg: 2018_09_17_30_40) inside chat on first load and get only the new msg and sendby if data updated while on get() getting whole document without any order Note: Code for Android app.
You can store the last fetched date, and only get the objects with date greater than last updated date.
db.collection('groups')
.where('participants', 'array-contains', 'user123')
.where('lastUpdated', '>', lastFetchTimestamp)
.orderBy('lastUpdated', 'desc')
Always getting whole document while any changes found on fire store.
The new Cloud Firestore database has different concepts than Firebase real-time database and should not be confused. There are no field-level permissions or access to a document. It's the entire document, or nothing. Cloud Firestore listeners fire on the document level. There is no way to get triggered with just newly updated data in a document.
Seeing your database, I can say that you haven't chosen the right schema by adding those messages under the chat property.
According to the official documentation:
Cloud Firestore is optimized for storing large collections of small documents.
You should consider create a new collection named messages and store each message as a separate document. In the link above, there are examples of how you can achieve that.