mysql - Flutter dart 不是常量表达式，意外的内核标记错误

Question

我正在使用 Flutter 制作一个简单的应用程序，并想连接到 mysql 数据库。我用作飞镖代码驱动程序的插件在这里。

但是，我收到以下错误：

    [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter ( 4789): 'package:sqljocky5/src/buffered_socket.dart': error: Not a constant expression: unexpected kernel tag InvalidExpression (19)
E/flutter ( 4789): #0      Connection.connect (package:sqljocky5/src/connection.dart:124:20)
E/flutter ( 4789): <asynchronous suspension>

捕获错误会产生相同的错误：

I/flutter ( 4789): opening connection
I/flutter ( 4789): connection open
I/flutter ( 4789): running example
I/flutter ( 4789): dropping tables
I/flutter ( 4789): 'package:sqljocky5/src/buffered_socket.dart': error: Not a constant expression: unexpected kernel tag InvalidExpression (19)

用于实例化连接的方法是从驱动程序的 github 示例中复制的：

class Example {
  ConnectionPool pool;

  Example(this.pool);

  Future run() async {
    // drop the tables if they already exist
    await dropTables();
    print("dropped tables");
    // then recreate the tables
    await createTables();
    print("created tables");
    // add some data
    await addData();
    // and read it back out
    await readData();
  }

  Future dropTables() {
    print("dropping tables");
    var dropper = new TableDropper(pool, ['pets', 'people']);
    return dropper.dropTables();
  }

  Future createTables() {
    print("creating tables");
    var querier = new QueryRunner(pool, [
      'create table people (id integer not null auto_increment, '
          'name varchar(255), '
          'age integer, '
          'primary key (id))',
      'create table pets (id integer not null auto_increment, '
          'name varchar(255), '
          'species text, '
          'owner_id integer, '
          'primary key (id),'
          'foreign key (owner_id) references people (id))'
    ]);
    print("executing queries");
    return querier.executeQueries();
  }

  Future addData() async {
    var query =
        await pool.prepare("insert into people (name, age) values (?, ?)");
    print("prepared query 1");
    var parameters = [
      ["Dave", 15],
      ["John", 16],
      ["Mavis", 93]
    ];
    await query.executeMulti(parameters);

    print("executed query 1");
    query = await pool
        .prepare("insert into pets (name, species, owner_id) values (?, ?, ?)");

    print("prepared query 2");
    parameters = [
      ["Rover", "Dog", 1],
      ["Daisy", "Cow", 2],
      ["Spot", "Dog", 2]
    ];
//          ["Spot", "D\u0000og", 2]];
    await query.executeMulti(parameters);

    print("executed query 2");
  }

  Future readData() async {
    print("querying");
    var result =
        await pool.query('select p.id, p.name, p.age, t.name, t.species '
            'from people p '
            'left join pets t on t.owner_id = p.id');
    print("got results");
    return result.forEach((row) {
      if (row[3] == null) {
        print("ID: ${row[0]}, Name: ${row[1]}, Age: ${row[2]}, No Pets");
      } else {
        print(
            "ID: ${row[0]}, Name: ${row[1]}, Age: ${row[2]}, Pet Name: ${row[3]}, Pet Species ${row[4]}");
      }
    });
  }
}

main() async {
  // OptionsFile options = new OptionsFile('connection.options');
  String user = "root";
  String password = "password";
  int port = 3306;
  String db = "db1";
  String host = "localhost";

  // create a connection
  print("opening connection");
  var pool = new ConnectionPool(
      host: host, port: port, user: user, password: password, db: db, max: 1);
  print("connection open");
  // create an example class
  var example = new Example(pool);
  // run the example
  print("running example");
  await example.run();
  // finally, close the connection
  print("K THNX BYE!");
  pool.closeConnectionsNow();
}

我怀疑这可能与 Dart 2 最近包含在 Flutter 中有关，这破坏了该驱动程序。我想尝试修复这个插件，但我不确定从哪里开始以及错误的确切含义。

标签： mysqldartflutter