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InstantDB Flutter

Basic Queries

InstantDB uses InstaQL, a simple yet powerful query language designed for real-time applications. All queries are reactive by default, meaning your UI automatically updates when data changes.

Simple Queries

Fetch All Records

Query all records of a specific entity type:

// Get all todos
final todosQuery = db.query({'todos': {}});


// Access the data
Watch((context) {
  final result = todosQuery.value;


  if (result.isLoading) {
    return const CircularProgressIndicator();
  }


  if (result.hasError) {
    return Text('Error: ${result.error}');
  }


  final todos = result.data!['todos'] as List;
  return ListView.builder(
    itemCount: todos.length,
    itemBuilder: (context, index) => TodoTile(todo: todos[index]),
  );
});

Filter with Where Clauses

Filter data using where conditions:

// Get completed todos only
final completedTodos = db.query({
  'todos': {
    'where': {'completed': true},
  },
});


// Get todos created today
final today = DateTime.now();
final startOfDay = DateTime(today.year, today.month, today.day);


final todaysTodos = db.query({
  'todos': {
    'where': {
      'createdAt': {'\$gte': startOfDay.millisecondsSinceEpoch},
    },
  },
});

Sorting and Limiting

Control the order and number of results:

// Get latest 10 todos, sorted by creation date
final latestTodos = db.query({
  'todos': {
    '\$': {
      'order': {'createdAt': 'desc'},
      'limit': 10,
    },
  },
});


// Multiple sort fields
final sortedTodos = db.query({
  'todos': {
    '\$': {
      'order': [
        {'priority': 'desc'},
        {'createdAt': 'asc'},
      ],
    },
  },
});

Query Operators

Comparison Operators

OperatorDescriptionExample
\$eqEqual (default){'status': 'active'}
\$neqNot equal{'status': {'\$neq': 'deleted'}}
\$gtGreater than{'score': {'\$gt': 100}}
\$gteGreater than or equal{'age': {'\$gte': 18}}
\$ltLess than{'price': {'\$lt': 50}}
\$lteLess than or equal{'quantity': {'\$lte': 10}}

Array Operators

OperatorDescriptionExample
\$inValue in array{'category': {'\$in': ['work', 'personal']}}
\$ninValue not in array{'status': {'\$nin': ['deleted', 'archived']}}

String Operators

OperatorDescriptionExample
\$containsContains substring{'title': {'\$contains': 'urgent'}}
\$startsWithStarts with{'email': {'\$startsWith': 'admin'}}
\$endsWithEnds with{'filename': {'\$endsWith': '.pdf'}}

React-Style Query Syntax

InstantDB Flutter supports React-style query syntax for compatibility:

final query = db.query({
  'todos': {
    '\$': {
      'where': {'completed': false},
      'order': {'createdAt': 'desc'},
      'limit': 20,
    },
  },
});

Both syntaxes are supported and can be used interchangeably.

Reactive Queries

Using InstantBuilder

The recommended way to use queries in widgets:

InstantBuilder(
  query: {
    'todos': {
      'where': {'userId': currentUserId},
    },
  },
  builder: (context, result) {
    if (result.isLoading) {
      return const CircularProgressIndicator();
    }


    if (result.hasError) {
      return Text('Error: ${result.error}');
    }


    final todos = result.data!['todos'] as List;
    return TodosList(todos: todos);
  },
)

Using InstantBuilderTyped

For better type safety, use the typed version:

InstantBuilderTyped<List<Map<String, dynamic>>>(
  query: {'todos': {}},
  transformer: (data) {
    final todos = (data['todos'] as List).cast<Map<String, dynamic>>();
    // Apply client-side sorting or filtering if needed
    todos.sort((a, b) => b['createdAt'].compareTo(a['createdAt']));
    return todos;
  },
  builder: (context, todos) {
    return ListView.builder(
      itemCount: todos.length,
      itemBuilder: (context, index) => TodoTile(todo: todos[index]),
    );
  },
)

One-time Queries

For non-reactive queries that execute once:

// Execute query once and get result
final result = await db.queryOnce({'todos': {}});


if (result.hasData) {
  final todos = result.data!['todos'] as List;
  print('Found ${todos.length} todos');
}

Complex Queries

Multiple Conditions

Combine multiple where conditions:

final complexQuery = db.query({
  'todos': {
    'where': {
      'completed': false,
      'priority': {'\$in': ['high', 'urgent']},
      'dueDate': {'\$lte': DateTime.now().millisecondsSinceEpoch},
      'assignee': {'\$neq': null},
    },
  },
});

Nested Conditions

Use logical operators for complex conditions:

final nestedQuery = db.query({
  'todos': {
    'where': {
      '\$or': [
        {'priority': 'urgent'},
        {
          '\$and': [
            {'priority': 'high'},
            {'dueDate': {'\$lte': DateTime.now().millisecondsSinceEpoch}},
          ],
        },
      ],
    },
  },
});

Query Performance

Indexing

Ensure your frequently queried fields are indexed in your InstantDB schema:

// This will perform better if 'userId' is indexed
final userTodos = db.query({
  'todos': {
    'where': {'userId': currentUserId},
  },
});

Pagination

Use limit and offset for large datasets:

final page1 = db.query({
  'todos': {
    '\$': {
      'limit': 20,
      'offset': 0,
    },
  },
});


final page2 = db.query({
  'todos': {
    '\$': {
      'limit': 20,
      'offset': 20,
    },
  },
});

Error Handling

Handle query errors gracefully:

InstantBuilder(
  query: {'todos': {}},
  errorBuilder: (context, error) {
    return Column(
      children: [
        const Icon(Icons.error, color: Colors.red),
        Text('Failed to load todos: $error'),
        ElevatedButton(
          onPressed: () {
            // Retry logic
          },
          child: const Text('Retry'),
        ),
      ],
    );
  },
  builder: (context, result) {
    // Success case
    final todos = result.data!['todos'] as List;
    return TodosList(todos: todos);
  },
)

Next Steps

Learn more about advanced querying features: