DBAS.SQLite.Flutter

Flutter plugin that provides access to SQLite databases for Android, iOS, macOS, Linux, Windows and Web platforms.

Features

Cross-Platform Support

• Android - Native library integration
• iOS - xcframework with optimized performance
• macOS - xcframework for both development and production
• Linux - Native shared libraries
• Windows - DLL integration
• Web - WASM SQLite via dedicated Web Worker with OPFS persistence

Connection Pool (WAL Mode)

• openDb() automatically creates a C-level connection pool with 1 writer + 4 readers (configurable)
• WAL mode enables concurrent reads and writes
• Pool is fully transparent -- no API changes needed
• Reads automatically use pool readers; writes use the dedicated writer
• Falls back to single connection if pool creation fails or readerPoolSize = 0
• Native pool has mutex-protected reader acquire/release for thread safety

Thread Safety & Parallel Readers

• Writer lock: serializes all write operations (executeSql, transactions) on both web and native
• Independent readers: each executeReader call returns a DbasSqliteReader with its own pool connection -- multiple readers can be active simultaneously
• Pool readers are acquired non-blocking; if all are busy, the reader falls back to the writer connection
• Transactions hold the writer lock for their full duration
• Reads within a transaction use the writer connection to see uncommitted data
• Readers must be closed explicitly via reader.close() (or auto-closed when readRow() returns false) before the connection can be reused
• closeDb() automatically closes all active readers, then releases all locks and unblocks any pending operations -- no risk of use-after-free on lingering readers

Background FFI Worker (Native)

• All heavy FFI operations (executeSql, prepareQuery, readRow, openDb, closeDb) run on a dedicated background isolate
• Column data is pre-fetched into a Dart-side cache after each readRow -- getColumn* calls are synchronous reads from Dart memory, not FFI round-trips
• Bind operations remain synchronous on the main isolate for performance

True Streaming I/O (Web)

• attachStreamDb(stream): Streams a database to OPFS chunk by chunk via attachStreamBegin/attachStreamChunk/attachStreamEnd with ACK-based backpressure. The complete file is never buffered in Dart memory -- critical for large databases (500 MB+)
• getContent(): Streams the database from OPFS chunk by chunk. Supports both Transferable Streams (Chrome/Firefox) and chunked postMessage fallback (Safari)
• streamCopyDb(destDbName): Copies between OPFS files chunk by chunk

Database Operations

• Lifecycle

  • getInstance(dbName:) - Get singleton instance for a database
  • openDb({readerPoolSize}) - Open database with connection pool
  • closeDb() - Close database connection (automatically closes all active readers)
  • isOpened() - Check connection status
  • getAppDatabasePath() - Get platform-specific database path
  • databaseExists() - Check if the database file exists
  • dropDb() - Delete the database file (including WAL and SHM)

• Database Content

  • attachDb(bytes) - Attach a database from raw bytes
  • attachStreamDb(stream) - Attach a database from a byte stream
  • streamCopyDb(destDbName) - Stream-copy database to a new name
  • getContent() - Get the raw bytes of the database file

• SQL Execution

  • executeSql(sql, {params, nameParams}) - Execute DDL/DML statements with optional positional or named parameters
  • executeReader(sql, {params, nameParams}) - Prepare a SELECT query, returns an independent DbasSqliteReader

• Transactions

  • beginTransaction() - Begin a new transaction (idempotent)
  • commit() - Commit the current transaction (idempotent)
  • rollback() - Rollback the current transaction (idempotent)
  • transaction(action) - Execute an action within a transaction with automatic commit/rollback
  • isInTransaction - Check if a transaction is currently active

Data Retrieval (DbasSqliteReader)

• readRow() - Advance to next row (true if available, false and auto-closes when done)
• close() - Manually close the reader and release its connection
• Column Access (with nullable variants)
  • getColumnText(index) / getColumnNullableText(index) - Get string value
  • getColumnInt(index) / getColumnNullableInt(index) - Get integer value
  • getColumnBool(index) / getColumnNullableBool(index) - Get boolean value
  • getColumnDouble(index) / getColumnNullableDouble(index) - Get double value
  • getColumnDecimal(index) / getColumnNullableDecimal(index) - Get decimal value
  • getColumnDateTime(index) / getColumnNullableDateTime(index) - Get DateTime value
  • getColumnTime(index) / getColumnNullableTime(index) - Get Duration value
  • getColumnEnum<T>(index, values) / getColumnNullableEnum<T>(index, values) - Get enum value
  • getColumnBlob(index) / getColumnNullableBlob(index) - Get binary data
  • getColumnValue(index) - Get typed value based on SQLite column type
  • isColumnNull(index) - Check if column is NULL
  • getColumnType(index) - Get column data type
  • getColumnName(index) - Get column name
  • getColumnCount() - Get number of columns

Query Information

• getLastInsertedId() - Get last inserted row ID

Installation

Add to your pubspec.yaml:

dependencies:
  dbas_sqlite: ^2.4.1

Or install with the Dart CLI:

flutter pub add dbas_sqlite

Setup

Mobile & Desktop

No additional setup required. Native libraries are automatically bundled.

Web Setup

The WASM module and Web Worker are bundled as Flutter assets and loaded automatically by the plugin. No manual file copying or <script> tags needed.

The worker runs inside a dedicated Web Worker with OPFS persistence. Requires a modern browser with OPFS support (Chrome 86+, Firefox 111+, Safari 15.2+) served over HTTPS or localhost.

Usage

Basic Example

import 'package:dbas_sqlite/dbas_sqlite.dart';

// Get database instance
final db = await DbasSqlite.getInstance(dbName: 'myapp.db');

// Open database (creates pool with WAL mode)
await db.openDb();

// Create table
final createStmt = await db.prepareQuery('''
  CREATE TABLE IF NOT EXISTS users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    email TEXT UNIQUE,
    age INTEGER
  )
''');
try {
  await createStmt.executeSql();
} finally {
  await createStmt.close();
}

// Insert with positional parameters
final insertStmt = await db.prepareQuery(
  'INSERT INTO users (name, email, age) VALUES (?, ?, ?)',
);
try {
  await insertStmt.executeSql(params: ['John Doe', 'john@example.com', 30]);
  print('Inserted user with id: ${insertStmt.getLastInsertedId()}');
} finally {
  await insertStmt.close();
}

// Query data
final selectStmt = await db.prepareQuery('SELECT * FROM users WHERE age > ?');
try {
  final reader = await selectStmt.executeReader(params: [25]);
  try {
    while (await reader.readRow()) {
      final name = reader.getColumnText(0);
      final email = reader.getColumnNullableText(1);
      final age = reader.getColumnInt(2);
      print('$name ($email) - age: $age');
    }
  } finally {
    await reader.close();
  }
} finally {
  await selectStmt.close();
}

await db.closeDb();

Statement Reuse

A prepared statement can be executed many times with different params — the bind buffer is replayed against a fresh native handle on each call:

final stmt = await db.prepareQuery('INSERT INTO users (name) VALUES (?)');
try {
  for (final name in ['Alice', 'Bob', 'Carol']) {
    await stmt.executeSql(params: [name]);
  }
} finally {
  await stmt.close();
}

Named Parameters

final stmt = await db.prepareQuery(
  'INSERT INTO users (name, email, age) VALUES (:name, :email, :age)',
);
try {
  await stmt.executeSql(nameParams: {
    'name': 'Jane Smith',
    'email': 'jane@example.com',
    'age': 28,
  });
} finally {
  await stmt.close();
}

// By default, extra named parameters not present in the SQL are silently
// ignored (C#/SQLite behavior). To throw instead:
db.throwOnMissingNamedParams = true;

Rich Types

import 'package:decimal/decimal.dart';

// Supports Decimal, bool, DateTime, Duration, Enum and Blob
final insStmt = await db.prepareQuery(
  'INSERT INTO products (name, price, active) VALUES (?, ?, ?)',
);
try {
  await insStmt.executeSql(
    params: ['Widget', Decimal.parse('19.99'), true],
  );
} finally {
  await insStmt.close();
}

final selStmt = await db.prepareQuery('SELECT name, price, active FROM products');
try {
  final reader = await selStmt.executeReader();
  try {
    while (await reader.readRow()) {
      final name = reader.getColumnText(0);
      final price = reader.getColumnDecimal(1);
      final active = reader.getColumnBool(2);
      print('$name - \$$price (active: $active)');
    }
  } finally {
    await reader.close();
  }
} finally {
  await selStmt.close();
}

Transactions

// Automatic commit/rollback
await db.transaction((tx) async {
  final stmt = await tx.prepareQuery('INSERT INTO users (name) VALUES (?)');
  try {
    await stmt.executeSql(params: ['Alice']);
    await stmt.executeSql(params: ['Bob']);
  } finally {
    await stmt.close();
  }
});

// Manual control
await db.beginTransaction();
try {
  final stmt = await db.prepareQuery('INSERT INTO users (name) VALUES (?)');
  try {
    await stmt.executeSql(params: ['Alice']);
  } finally {
    await stmt.close();
  }
  await db.commit();
} catch (_) {
  await db.rollback();
  rethrow;
}

Connection Pool

// Default: 4 readers (WAL mode)
await db.openDb();

// Custom pool size
await db.openDb(readerPoolSize: 8);

// Single connection (no pool)
await db.openDb(readerPoolSize: 0);

Stream Copy

// Copy database to a backup
await db.streamCopyDb('myapp_backup.db');

Minimum Platform Versions

Platform	Minimum Version
Android	API 35
iOS	16.0
macOS	13.0 (Ventura)
Linux	x86_64
Windows	x86_64
Web	Modern browsers with OPFS support

Platform Notes

• iOS/macOS: Uses xcframework for optimal performance
• Android: Native library automatically included (NDK r29)
• Windows/Linux: Dynamic libraries bundled with app
• Web: WASM module runs in a dedicated Web Worker with OPFS persistence. All heavy operations are serialized through the worker — column data is cached in Dart memory after each readRow for synchronous access

License

This project is licensed under the terms specified in the LICENSE file.