parameters.md

Passing parameters to widgets

Parameters are used to pass data from one widget to another, and since you can't modify the widget code (generated file), the XML structure enables you to declare the parameter(s) as follow:

<MyPage controller="MyController">
  <!-- basic -->
  <param type="CategoryModel" name="category" />

  <!-- required -->
  <param type="int" name="index" required="true" />
  <!-- 
    final int index;
    MyPage({@required this.index})
  -->

  <!-- default value -->
  <param type="int" name="index" value="0" /> 
  <!--
    final int index;
    MyPage({this.index = 0})
  -->
  
  <!-- passing parameters to super class -->
  <param type="UniqueKey" name="key" superParamName="key" />
  <!-- 
    final UniqueKey key;
    MyPage({this.key}) : super(key: key);
  -->
  
  <!-- passing parameters to super class (without initializing field) -->
  <param type="UniqueKey" superParamName="key" />
  <!-- MyPage({UniqueKey key}) : super(key: key) -->
  ...
</MyPage>

And you can access it directly in the XML file:

  <Text text="ctrl.category.name" />

Or in the controller class after didLoad(), not in the constructor:

  @override
  void didLoad() {
    print(category.name);
  }

Then, from another widget, pass parameter's value as usual:

<MyWidget category="...value...">
</MyWidget>