react property Null safety

Map<String, dynamic>? react
read / write

It is useful for components whose data view should reactively update when on or more dependent components change their states.

For example, a widget to display the results can depend on the search widget to filter the results.

  • key string one of and, or, not defines the combining clause.
    • and clause implies that the results will be filtered by matches from all of the associated widget states.
    • or clause implies that the results will be filtered by matches from at least one of the associated widget states.
    • not clause implies that the results will be filtered by an inverse match of the associated widget states.
  • value string or Array or Object
    • string is used for specifying a single widget by its id.
    • Array is used for specifying multiple components by their id.
    • Object is used for nesting other key clauses. An example of a react clause where all three clauses are used and values are Object, Array and string.
{
		'and': {
			'or': ['CityComp', 'TopicComp'],
			'not': 'BlacklistComp',
		},
	}

Here, we are specifying that the results should update whenever one of the blacklist items is not present and simultaneously any one of the city or topics matches.

Implementation

/// An example of a `react` clause where all three clauses are used and values are `Object`, `Array` and `string`.

///  ```dart
/// {
///		'and': {
///			'or': ['CityComp', 'TopicComp'],
///			'not': 'BlacklistComp',
///		},
///	}
/// ```

/// Here, we are specifying that the results should update whenever one of the blacklist items is not present and simultaneously any one of the city or topics matches.
Map<String, dynamic>? react;