flutter/create-catalog-item

Create CatalogItem

Goal

To correctly implement a GenUI CatalogItem based on a provided json_schema_builder Schema, including its corresponding data class, CatalogItem instance, and Widget class. This ensures the AI model can properly generate and interact with the UI component.

Instructions

When tasked with creating a CatalogItem from a Schema, follow these steps:

1. Create the Data Class:

   • Name it _<SchemaName>Data (e.g., if schema is myCardSchema, data class is _MyCardData).
   • Add final fields for each property defined in the schema.
   • Create a factory _<SchemaName>Data.fromJson(Map<String, Object?> json) method.
   • Use a try-catch block to parse the properties and return a new instance.
   • Cast each property from the json map to its expected type, e.g., title: json['title'] as String, or action: json['action'] as JsonMap?,.
   • Throw an Exception('Invalid JSON for _<SchemaName>Data') in the catch block if an error occurs.

2. Create the CatalogItem Instance:

   • Name it identical to the schema name but without the "Schema" suffix (e.g., myCard for myCardSchema).
   • Declare as a final CatalogItem.
   • Set name to the capitalized version of the name (e.g., 'MyCard').
   • Set dataSchema to the provided schema.
   • Implement the widgetBuilder: (itemContext):
     • Cast itemContext.data to Map<String, Object?>.
     • Parse the data using the data class fromJson method: _<SchemaName>Data.fromJson(json).
     • Return the corresponding Widget class and pass the required data.
     • If the schema includes an action callback (like onCompleted), implement it here. You must parse the action context using resolveContext and dispatch an event using itemContext.dispatchEvent(...).

3. Create the Widget Class:

   • Name it _<CapitalizedSchemaName> (e.g., _MyCard).
   • Inherit from StatelessWidget or StatefulWidget depending on state requirements.
   • Add the Data Class as a required property (e.g., final _<SchemaName>Data data;).
   • Add any required callback properties (e.g., final void Function(int) onCompleted;).
   • Implement the build method using Flutter Material components (e.g., Card, Column, Text). Make sure each data field in the data class is displayed, and that actions are represented by buttons or other interactive elements.

Examples

Input Schema

final basicCardSchema = S.object(
  properties: {
    'component': S.string(enumValues: ['BasicCard']),
    'title': S.string(),
    'description': 
    'action': A2uiSchemas.action(),
  },
  required: ['title'],
);

Expected Output

class _BasicCardData {
  final String title;
  final JsonMap? action;

  _BasicCardData({required this.title, this.action});

  factory _BasicCardData.fromJson(Map<String, Object?> json) {
    try {
      return _BasicCardData(
        title: json['title'] as String,
        action: json['action'] as JsonMap?,
      );
    } catch (e) {
      throw Exception('Invalid JSON for _BasicCardData: $e');
    }
  }
}

final basicCard = CatalogItem(
  name: 'BasicCard',
  dataSchema: basicCardSchema,
  widgetBuilder: (itemContext) {
    final json = itemContext.data as Map<String, Object?>;
    final data = _BasicCardData.fromJson(json);

    return _BasicCard(
      data: data,
      onTap: () async {
        final action = data.action;
        if (action == null) return;
        final event = action['event'] as JsonMap?;
        final name = (event?['name'] as String?) ?? '';
        final JsonMap contextDefinition =
            (event?['context'] as JsonMap?) ?? <String, Object?>{};
        final JsonMap resolvedContext = await resolveContext(
          itemContext.dataContext,
          contextDefinition,
        );
        itemContext.dispatchEvent(
          UserActionEvent(
            name: name,
            sourceComponentId: itemContext.id,
            context: resolvedContext,
          ),
        );
      }
    );
  },
);

class _BasicCard extends StatelessWidget {
  final _BasicCardData data;
  final VoidCallback onTap;

  const _BasicCard({super.key, required this.data, required this.onTap});

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(data.title),
        onTap: onTap,
      ),
    );
  }
}

Constraints

• Ensure proper use of try-catch blocks and type casting when parsing JSON in fromJson.
• Make sure action resolution accurately fetches variables via resolveContext and uses itemContext.dispatchEvent when actions are present in the Schema.