SQLHELPER

Description

SQLHelper is a library used as a DB abstraction for java. To map DB table into java objects

SQLHelper takes care of relations between table and bind java objects based on that relation.

It supports transactions and caching.

Usage

@Table("address") //sql table name
public class Address {

    @PrimaryKey
    @Property(name="id", type = SQLTypes.Long) //name is the column
    private Long id;

    @Property(name="full_address")
    private String fullAddress;

    @OneToOne(targetEntity = Customer.class, inverserdBy = "customer_id")
    //table address has column customer_id referencing customer table.
    private Customer customer;

    //setters and getters
}

@Table("customer")
public class Customer {

    @PrimaryKey
    @Property(name = "id", type = SQLTypes.Long)
    private Long id;

    @Property(name = "firstname")
    private String firstName;

    @Property(name = "lastname")
    private String lastName;

    @OneToOne(targetEntity = Address.class, mappedBy = "customer_id")
    private Address address;

    @OneToMany(targetEntity = PhoneNumber.class, mappedBy="customer_id")
    private List<PhoneNumber> phoneNumbers;

    //setters and getters
}

Initialization of instance

to create an object of your class use:

Customer c = EntityManager.GetInstance().GetRepository(Customer.class).create();

Setters and Getters

if you call : customer.setAddress(address);, automatically address.getCustomer() will be equal to customer

and that is valid for all relations: one to one one to many many to one many to many

As of examples:

Customer c = EntityManager.GetInstance().GetRepository(Customer.class).create();
Address a = EntityManager.GetInstance().GetRepository(Address.class).create();
c.setAddress(a);
assertTrue(a.getCustomer() != null);
PhoneNumber p = EntityManager.GetInstance().GetRepository(PhoneNumber.class).create();
p.setCustomer(c);
assertTrue(c.getPhoneNumbers().size() == 1);
p.setCustomer(null);
assertTrue(c.getPhoneNumbers().size() == 0);
c.getPhoneNumbers().add(p);
assertTrue(p.getCustomer() != null);

Transactions

Starting Transaction

To begin a transaction use:

    EntityManager.GetInstance().beginTransaction();

Persistance

To persist objects call:

 EntityManager.GetInstance().persist(object);

To delete objects:

EntityManager.GetInstance().remove(object);

To commit:

EntityManager.GetInstance().commit();

To create savepoint:

Savepoint sp = EntityManager.GetInstance().setSavePoint();

To rollback:

EntityManager.GetInstance().rollBack(sp); //Rollback to SAVEPOINT
//OR
EntityManager.GetInstance().rollBack();