late_init 1.1.0

Execute code at a later stage, but before build has been called for the first time. Useful for initializations that depends on the context

late_init

Execute code at a later stage, but before build has been called for the first time. Useful for initializations that depends on the context

*This package was inspired by after_layout

Quick Usage

Given a statefull widget:

class MyWidget extends StatefulWidget {
  @override
  MyWidgetState createState() => MyWidgetState();
}

class MyWidgetState extends State<MyWidget> {
  @override
  Widget build(BuildContext context) {
    //TODO: implement build method
  }
}

Add with LateInitMixin<MyWidget> mixin to your State<MyWidget> class and then implement the void lateInitState() method.

class MyWidgetState extends State<MyWidget> /*HERE. Add this bit -->*/ with LateInitMixin<MyWidget> {
  //Code in this method will be called once at a later stage where [context]
  //can be used for actions such as `ModalRoute.of(context)`, `Provider.of<>(context)`
  @override
  void lateInitState() {
    final someId = ModalRoute.of(context).settings.arguments as String;
  }
  
  // The rest of the widget...
}

Complete example

This demo showcases how this package resolves the shortcomings shown above:

import 'package:flutter/material.dart';
import 'package:late_init/late_init.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Late Init - Example',
      home: new HomeScreen(),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  MyWidgetState createState() => MyWidgetState();
}

class MyWidgetState extends State<MyWidget> with LateInitMixin<MyWidget> {
  @override
  void lateInitState() {
    final someId = ModalRoute.of(context)!.settings.arguments as String?;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(color: Colors.red),
    );
  }
}

What not to do with this package

If you're trying to get the size, position or something that depends on the layout of the widget, using lateInitState WILL NOT DO, for that kind of information the widget needs to be rendered at least once before you can get that info, if that's what you're trying to do, then take a look at after_layout which is a package similar to this, but to run code after the first layout.