In this article, you will learn how to change Firebase Realtime Database/Cloud Firestore queries without changing the whole adapter of a RecyclerView in Android by using the FirebaseUI-Android library.
Let’s say you need to populate a list using RecyclerViewto show data loaded from Firebase Realtime DatabaseorCloud Firestore and you have implemented a custom RecyclerView.Adapter to hold data or you used FirebaseUI-Android which is an official open-source library developed by the Firebase team. In this article, we’re going to use theFirebaseUI-Android library.
We’ll load data from Firebase Realtime Database/Cloud Firestore and populate a RecyclerView (Simple + Paginated)using the adapter. After that, we’ll change/filter the query based on some user interaction at runtime without changing whole adapter.
In the end, you will see app like this 👇. After clicking on one of the buttons, data in RecyclerView will be replaced by new data.
Demo output after changing the query.
🔥 About FirebaseUI 😃
*FirebaseUI is an open-source library for Android that allows you to quickly connect common UI elements to Firebase APIs. (see here)*It makes it easy to bind data from Firebase Realtime Database** or Cloud Firestore to your app’s UI 🎨.
FirebaseUI-Android provides a number of adapters, such as:
FirebaseRecyclerAdapter— for binding Firebase Realtime DatabaseFirebaseRecyclerPagingAdapter— for binding Firebase Realtime Database with pagination supportFirestoreRecyclerAdapter— for binding Cloud FirestoreFirestorePagingAdapter— for binding Cloud Firestore with pagination support
⚡️ Getting Started
Let’s write some code!
Open Android Studio and create a new project. Alternatively, you can simply clone this repository. This is a very simple app for showing a list of posts.
Gradle Setup
In the app module of build.gradle, include following dependencies.
dependencies {
// Firebase SDKs
implementation 'com.google.firebase:firebase-firestore:21.4.1'
implementation 'com.google.firebase:firebase-database:19.2.1'
// FirebaseUI for Real-time database
implementation 'com.firebaseui:firebase-ui-database:6.2.0'
// FirebaseUI for Cloud Firestore
implementation 'com.firebaseui:firebase-ui-firestore:6.2.0'
// Paging Library (For Pagination Only)
implementation 'android.arch.paging:runtime:1.0.1'
}If you’re unsure how to use FirebaseUI 🔥, check out the official source here. Or, take a look at the official sample👇.
https://github.com/firebase/quickstart-android
⚡️ How to Change the Query 🤔
In the adapter classes of FirebaseUI library, there’s a method updateOptions() which initialises an adapter with new options. Whenever this is invoked, the respective RecyclerView is populated with new data.
💻 Let’s Change the Queries 🔥
#1 — Firebase Realtime Database
Here mAdapter is an instance of FirebaseReyclerAdapter. The new instance of FirebaseRecyclerOptions is created with a query: newQuery. Finally, we call updateOptions() . After this, you can observe the change in RecyclerView. 😃
fun changeQuery() {
val newQuery = mBaseQuery
.orderByChild("timestamp")
.limitToLast(100)
// Make new options
val newOptions = FirebaseRecyclerOptions.Builder<Post>()
.setQuery(newQuery, Post::class.java)
.build()
// Change options of adapter.
mAdapter.updateOptions(newOptions)
}The same can be done in a paging adapter i.e. FirebaseRecyclerPagingAdapter. Just a small change is there while making options is we have to pass PagedList.Config as a parameter along with query in setQuery() .
#2 — Firebase Cloud Firestore
Same as above, here mAdapter is an instance of FirestoreReyclerAdapter.
fun changeQuery() {
val newQuery = mCollectionReference
.orderBy("timestamp")
.whereEqualTo("seen", false)
.limitToLast(100)
// Make new options
val newOptions = FirestoreRecyclerOptions.Builder<Post>()
.setQuery(newQuery, Post::class.java)
.build()
// Change options of adapter.
mAdapter.updateOptions(newOptions)
}Again, the same can be done in a paging adapter i.e. FirestorePagingAdapter.
We have successfully changed queries at runtime using the FirebaseUI library😃.
The source code for this article is available in this GitHub repo.
Thank You! 😃
Resources
https://github.com/PatilShreyas/FirebaseRecyclerUpdateQuery-Demo