D 語言的 ORM 框架：HibernateD

HibernateD 是 D 語言的 ORM 框架，類似 Java 的 Hibernate，示例代碼：

import hibernated.core;

// Annotations of entity classes
class User {
    long id;
    string name;
    Customer customer;
    @ManyToMany // cannot be inferred, requires annotation
    LazyCollection!Role roles;
}
class Customer {
    int id;
    string name;
    // Embedded is inferred from type of Address
    Address address;

Lazy!AccountType accountType; // ManyToOne inferred

User[] users; // OneToMany inferred

this() {
    address = new Address();
}

}
@Embeddable
class Address {
    string zip;
    string city;
    string streetAddress;
}
class AccountType {
    int id;
    string name;
}
class Role {
    int id;
    string name;
    @ManyToMany // w/o this annotation will be OneToMany by convention
    LazyCollection!User users;
}
// create metadata from annotations
EntityMetaData schema = new SchemaInfoImpl!(User, Customer, AccountType, 
                                 T1, TypeTest, Address, Role, GeneratorTest);
// setup DB connection factory
MySQLDriver driver = new MySQLDriver();
string url = MySQLDriver.generateUrl("localhost", 3306, "test_db");
string[string] params = MySQLDriver.setUserAndPassword("testuser", "testpasswd");
DataSource ds = ConnectionPoolDataSourceImpl(driver, url, params);
// create session factory
Dialect dialect = new MySQLDialect();
SessionFactory factory = new SessionFactoryImpl(schema, dialect, ds);
scope(exit) factory.close();
// Create schema if necessary
{
// get connection
Connection conn = ds.getConnection();
scope(exit) conn.close();
// create tables if not exist
factory.getDBMetaData().updateDBSchema(conn, false, true);
}
// Now you can use HibernateD
// create session
Session sess = factory.openSession();
scope(exit) sess.close();
// use session to access DB
// read all users using query
Query q = sess.createQuery("FROM User ORDER BY name");
User[] list = q.list!User();
// create sample data
Role r10 = new Role();
r10.name = "role10";
Role r11 = new Role();
r11.name = "role11";
Customer c10 = new Customer();
c10.name = "Customer 10";
User u10 = new User();
u10.name = "Alex";
u10.customer = c10;
u10.roles = [r10, r11];
sess.save(r10);
sess.save(r11);
sess.save(c10);
sess.save(u10);
// load and check data
User u11 = sess.createQuery("FROM User WHERE name=:Name").
                           setParameter("Name", "Alex").uniqueResult!User();
assert(u11.roles.length == 2);
assert(u11.roles[0].name == "role10" || u11.roles.get()[0].name == "role11");
assert(u11.roles[1].name == "role10" || u11.roles.get()[1].name == "role11");
assert(u11.customer.name == "Customer 10");
assert(u11.customer.users.length == 1);
assert(u11.customer.users[0] == u10);
assert(u11.roles[0].users.length == 1);
assert(u11.roles[0].users[0] == u10);
// remove reference
u11.roles.get().remove(0);
sess.update(u11);
// remove entity
sess.remove(u11);</pre>

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