mysql_client

Native MySQL client written in Dart for Dart

See example directory for examples and usage

Tested with:

• MySQL Percona Server 5.7 and 8 versions
• MariaDB 10 version

Roadmap

• [x] Auth with mysql_native_password
• [x] Basic connection
• [x] Connection pool
• [x] Query placeholders
• [x] Transactions
• [x] Prepared statements (real, not emulated)
• [x] SSL connection
• [x] Auth using caching_sha2_password (default since MySQL 8)
• [x] Iterating large result sets
• [x] Typed data access
• [ ] Send data in binary form when using prepared stmts (do not convert all into strings)
• [x] Multiple resul sets

Usage

Create connection pool

final pool = MySQLConnectionPool(
  host: '127.0.0.1',
  port: 3306,
  userName: 'your_user',
  password: 'your_password',
  maxConnections: 10,
  databaseName: 'your_database_name', // optional,
);

Or single connection

final conn = await MySQLConnection.createConnection(
  host: "127.0.0.1",
  port: 3306,
  userName: "your_user",
  password: "your_password",
  databaseName: "your_database_name", // optional
);

// actually connect to database
await conn.connect();

Warning By default connection is secure. If you don't want to use SSL (TLS) connection, pass secure: false

Query database

var result = await pool.execute("SELECT * FROM book WHERE id = :id", {"id": 1});

Print result

  for (final row in result.rows) {
    print(row.assoc());
  }

There are two groups of methods to access column data. First group returns result as strings. Second one (methods starting with typed prefix) performs conversion to specified type.

F.e.:

row.colAt(0); // returns first column as String
row.typedColAt<int>(0); // returns first column as int 

Look at example/main_simple_conn.dart for other ways of getting column data, including typed data access.

Prepared statements

This library supports real prepared statements (using binary protocol).

Prepare statement

var stmt = await conn.prepare(
  "INSERT INTO book (author_id, title, price, created_at) VALUES (?, ?, ?, ?)",
);

Execute with params

await stmt.execute([null, 'Some book 1', 120, '2022-01-01']);
await stmt.execute([null, 'Some book 2', 10, '2022-01-01']);

Deallocate prepared statement

await stmt.deallocate();

Transactions

To execute queries in transaction, you can use transactional() method on connection or pool object Example:

await pool.transactional((conn) async {
  await conn.execute("UPDATE book SET price = :price", {"price": 300});
  await conn.execute("UPDATE book_author SET name = :name", {"name": "John Doe"});
});

In case of exception, transaction will roll back automatically.

Iterating large result sets

In case you need to process large result sets, you can use iterable result set. To use iterable result set, pass iterable = true, to execute() or prepare() methods. In this case rows will be ready as soon as they are delivered from the network. This allows you to process large amount of rows, one by one, in Stream fashion.

When using iterable result set, you need to use result.rowsStream.listen instead of result.rows to get access to rows.

Example:

// make query (notice third parameter, iterable=true)
var result = await conn.execute("SELECT * FROM book", {}, true);

result.rowsStream.listen((row) {
  print(row.assoc());
});

Multiple statements queries

This library supports multiple statements in query() method. If your query contains multiple statements, result will contain next property, which will point to the next result set.

IResulSet class implements Iterable interface, so you can iterate throw all result sets using for..in loop.

Multple statements are not supported for prepared statements and iterable result sets.

For example:

final resultSets = await conn.execute(
  "SELECT 1 as val_1_1; SELECT 2 as val_2_1, 3 as val_2_2",
);

assert(resultSets.next != null);

for (final result in resultSets) {
  // for every result set
  for (final row in result.rows) {
    // for every row in result set
    print(row.assoc());
  }
}

Tests

To run tests execute

dart test

Error handling

This library throws tree types of exceptions: MySQLServerException, MySQLClientException and MySQLProtocolException. See api reference for description of each type.

When exception is thrown, connection can be left in connected or closed state.

As a general rule, if cause of exception is MySQL server error packet, connection will be left in connected state and can be reused. If cause of exception is logical error, such as unexpected packet or something inside parsing of mysql protocol, connection will be closed and can not be used anymore.

It's up to developer to check connection state after catching exception. Inside your catch block, you can check connection status using conn.connected getter and decide what to do next.

Troubleshooting

There is separate logging branch of mysql_client. This branch will stay in sync with main branch of this repository, with one main difference - it has logging enabled.

If you have issues, you can temporary switch to logging branch, run your app with --enable-asserts and check log messages.

Here is how you can switch to logging branch in your pubspec.yaml file:

 mysql_client: 
    git: 
      url: https://github.com/zim32/mysql.dart.git
      ref: logging

Don't forget to switch back again, when you're done with debugging.

Support the author 🇺🇦

If you like this project and want to support the author, you can donate me via paypal donations service.