sqlite3 #

Provides Dart bindings to SQLite via dart:ffi.

Using this library #

1. Make sure sqlite3 is available as a shared library in your environment (see supported platforms below).
2. Import package:sqlite3/sqlite3.dart.
3. Use sqlite3.open() to open a database file, or sqlite3.openInMemory() to open a temporary in-memory database.
4. Use Database.execute or Database.prepare to execute statements directly or by preparing them first.
5. Don't forget to close prepared statements or the database with dispose() if you no longer need it.

For a more complete example on how to use this library, see the example.

Supported platforms #

You can use this library on any platform where you can obtain a DynamicLibrary with symbols from sqlite3. In addition, this package experimentally supports the web through WebAssembly.

Here's how to use this library on the most popular platforms:

• Android: Flutter users can depend on the sqlite3_flutter_libs package to ship the latest sqlite3 version with their app.
• iOS: Contains a built-in version of sqlite that this package will use by default. When using Flutter, you can also depend on sqlite3_flutter_libs to ship the latest sqlite3 version with your app.
• Linux: Flutter users can depend on sqlite3_flutter_libs to ship the latest sqlite3 version with their app. Alternatively, or when not using Flutter, you can install sqlite3 as a package from your distributions package manager (like libsqlite3-dev on Debian), or you can manually ship sqlite3 with your app (see below).
• macOS: Contains a built-in version of sqlite that this package will use by default. Also, you can depend on sqlite3_flutter_libs if you want to include the latest sqlite3 version with your app.
• Windows: Flutter users can depend on sqlite3_flutter_libs to ship the latest sqlite3 version with their app. When not using Flutter, you need to manually include sqlite3 (see below).
• Web: See web support below.

On Android, iOS and macOS, you can depend on the sqlcipher_flutter_libs package to use SQLCipher instead of SQLite. Just be sure to never depend on both sqlcipher_flutter_libs and sqlite3_flutter_libs!

Manually providing sqlite3 libraries #

Instead of using the sqlite3 library from the OS, you can also ship a custom sqlite3 library along with your app. You can override the way this package looks for sqlite3 to instead use your custom library. For instance, if you release your own sqlite3.so next to your application, you could use:

import 'dart:ffi';
import 'dart:io';

import 'package:path/path.dart';
import 'package:sqlite3/open.dart';
import 'package:sqlite3/sqlite3.dart';

void main() {
  open.overrideFor(OperatingSystem.linux, _openOnLinux);

  final db = sqlite3.openInMemory();
  // Use the database
  db.dispose();
}

DynamicLibrary _openOnLinux() {
  final scriptDir = File(Platform.script.toFilePath()).parent;
  final libraryNextToScript = File(join(scriptDir.path, 'sqlite3.so'));
  return DynamicLibrary.open(libraryNextToScript.path);
}

Just be sure to first override the behavior and then use sqlite3.

Supported datatypes #

When binding parameters to queries, the supported types are ìnt, double, String, List<int> (for BLOB) and null. Result sets will use the same set of types. On the web (but only on the web), BigInt is supported as well.

WASM (web support) #

This package experimentally supports being used on the web with a bit of setup. The web version binds to a custom version of sqlite3 compiled to WebAssembly without Emscripten or any JavaScript glue code.

Setup #

To use this package on the web, you need:

• The sqlite3 library compiled as a WebAssembly module, available from the GitHub releases of this package. Note that, for this package, sqlite3 has to be compiled in a special way. Existing WebAssembly files from e.g. sql.js will not work with package:sqlite3/wasm.dart.
• A file system implementation, since websites can't by default access the host's file system. This package provides InMemoryFileSystem and an IndexedDbFileSystem implementation.

After putting sqlite3.wasm under the web/ directory of your project, you can open and use sqlite3 like this:

import 'package:http/http.dart' as http;
import 'package:sqlite3/common.dart';
import 'package:sqlite3/wasm.dart';

Future<WasmSqlite3> loadSqlite() async {
  final sqlite = await WasmSqlite3.loadFromUrl(Uri.parse('sqlite3.wasm'));
  final fileSystem = await IndexedDbFileSystem.open(dbName: 'my_app');
  sqlite.registerVirtualFileSystem(fileSystem, makeDefault: true);
  return sqlite;
}

The returned WasmSqlite3 has an interface compatible to that of the standard sqlite3 field in package:sqlite3/sqlite3.dart, databases can be opened in similar ways.

An example for such web folder is in example/web/ of this repo. To view the example, copy a compiled sqlite3.wasm file to web/sqlite3.wasm in this directory. Then, run dart run build_runner serve example:8080 and visit http://localhost:8080/web/ in a browser.

Another example/multiplatform/ uses common interface to sqlite3 on web and native platforms. To run this example, merge its files into a Flutter app.

Sharing code between web and a Dart VM #

The package:sqlite3/common.dart library defines common interfaces that are implemented by both the FFI-based native version in package:sqlite3/sqlite3.dart and the experimental WASM version in package:sqlite3/wasm.dart. By having shared code depend on the common interfaces, it can be used for both native and web apps.

Testing #

To run the tests of this package with wasm, either download the sqlite3.wasm file from the GitHub releases to example/web or compile it yourself (see compiling below).

To run tests on the Dart VM, Firefox and Chrome, use:

dart test -P full

Compiling #

Note: Compiling sqlite3 to WebAssembly is not necessary for users of this package, just grab the .wasm from the latest release on GitHub.

This section describes how to compile the WebAssembly modules from source. This uses a LLVM-based toolchain with components of the WASI SDK for C runtime components.

Setup

Linux

On Linux, you need a LLVM based toolchain capable of compiling to WebAssembly. On Arch Linux, the wasi-compiler-rt and wasi-libc packages are enough for this. On other distros, you may have to download the sysroot and compiler builtins from their respective package managers or directly from the WASI SDK releases.

With wasi in /usr/share/wasi-sysroot and the default clang compiler having the required builtins, you can setup the build with:

cmake -S assets/wasm -B .dart_tool/sqlite3_build --toolchain toolchain.cmake

macOS

On macOS, I'm installing cmake, llvm and binaryen through Homebrew. Afterwards, you can download the wasi sysroot and the compiler runtimes from the Wasi SDK project:

curl -sL https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/libclang_rt.builtins-wasm32-wasi-20.0.tar.gz | \
  tar x -zf - -C /opt/homebrew/opt/llvm/lib/clang/17*

curl -sS -L https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/wasi-sysroot-20.0.tar.gz | \
  sudo tar x -zf - -C /opt

Replace clang/17 with the correct directory if you're using a different version.

Then, set up the build with

cmake -Dwasi_sysroot=/opt/wasi-sysroot -Dclang=/opt/homebrew/opt/llvm/bin/clang -S assets/wasm -B .dart_tool/sqlite3_build --toolchain toolchain.cmake

Building

In this directory, run:

cmake --build .dart_tool/sqlite3_build/ -t output -j

The output target copies sqlite3.wasm and sqlite3.debug.wasm to example/web.

(Of course, you can also run the build in any other directory than .dart_tool/sqite3_build if you want to).

Customizing the WASM module #

The build scripts in this repository, which are also used for the default distribution of sqlite3.wasm attached to releases, are designed to mirror the options used by sqlite3_flutter_libs. If you want to use different options, or include custom extensions in the WASM module, you can customize the build setup.

To use regular sqlite3 sources with different compile-time options, alter assets/wasm/sqlite_cfg.h and re-run the build as described in compiling. Including additional extensions written in C is possible by adapting the CMakeLists.txt in assets/wasm.

A simple example demonstrating how to include Rust-based extensions is included in example/custom_wasm_build. The readme in that directory explains the build process in detail, but you still need the WASI/Clang toolchains described in the setup section.