Set Value - Stac

The Stac SetValue widget allows you to set multiple key-value pairs in the application’s state and optionally render a child widget. It’s useful for managing application state through JSON configuration.

Properties

Property	Type	Description
values	`List<Map<String, dynamic>>`	List of key-value pairs to set in the application state.
child	`StacWidget`	Optional child widget to render after the values are set.

Each item in values should contain:

key: The state key to set
value: The value to assign

Example

Dart
JSON
Preview

StacSetValue(
  values: [
    {'key': 'userName', 'value': 'John Doe'},
    {'key': 'isLoggedIn', 'value': true},
  ],
  child: StacText(data: 'Welcome!'),
)

{
  "type": "setValue",
  "values": [
    {
      "key": "userName",
      "value": "John Doe"
    },
    {
      "key": "isLoggedIn",
      "value": true
    }
  ],
  "child": {
    "type": "text",
    "data": "Welcome!"
  }
}

Initializing State on Screen Load

Use StacSetValue to initialize state when a screen loads:

StacScaffold(
  body: StacSetValue(
    values: [
      {'key': 'currentPage', 'value': 'home'},
      {'key': 'selectedTab', 'value': 0},
      {'key': 'filters', 'value': {'category': 'all', 'sortBy': 'date'}},
    ],
    child: StacColumn(
      children: [
        StacText(data: 'Home Page'),
        // ... rest of the UI
      ],
    ),
  ),
)

{
  "type": "scaffold",
  "body": {
    "type": "setValue",
    "values": [
      { "key": "currentPage", "value": "home" },
      { "key": "selectedTab", "value": 0 },
      { "key": "filters", "value": { "category": "all", "sortBy": "date" } }
    ],
    "child": {
      "type": "column",
      "children": [
        { "type": "text", "data": "Home Page" }
      ]
    }
  }
}

Reading State Values

After setting values with StacSetValue, you can read them using placeholder syntax {{key}}:

StacSetValue(
  values: [
    {'key': 'greeting', 'value': 'Hello'},
    {'key': 'user.name', 'value': 'Alice'},
  ],
  child: StacText(data: '{{greeting}}, {{user.name}}!'),
)

{
  "type": "setValue",
  "values": [
    { "key": "greeting", "value": "Hello" },
    { "key": "user.name", "value": "Alice" }
  ],
  "child": {
    "type": "text",
    "data": "{{greeting}}, {{user.name}}!"
  }
}

For action-based state updates (e.g., on button press), see StacSetValueAction.