Introduction

At the moment, fetchMovies() is being called from the MovieListing widget’s build method. A network call is made every time the build method is called, which can be lots of network operations if the build is triggered often.

Fetching movies at app startup

In this app, we want to fetch movies only once at the start of the application.

We can do so by calling fetchMovies() from initState() method.

The initState() method

initState() method is called exactly once for each State object it creates, whereas, the build() method of the Statefulwidget is called several times during the app’s lifetime.

  @override
  void initState() {
    super.initState();
    fetchMovies();
  }

The following code snippet shows the change we need to make to _MoviesListingState class :

class MoviesListing extends StatefulWidget {
 @override
 _MoviesListingState createState() => _MoviesListingState();
}

class _MoviesListingState extends State<MoviesListing> {

@override
void initState() {
 super.initState();
//movies are fetched only once at app’s start-up
 fetchMovies();
}


 @override
 Widget build(BuildContext context) {
fetchMovies(); //move this into initState method
...
 }
}