Database - neowu/core-ng-project GitHub Wiki

Design

One design principle of coreng is not twisting underlying driver api but providing facility. So the general design of Database access is based on directly JDBC mapping. Allow user perceive how app interacts with DB via JDBC calls, this enables us not only precise control of performance and also adding advanced JDBC feature easier if needed.

Repository is mainly syntax sugar, helps to generate essential SQL statement via annotations.

Config

In module, to register entity

db().repository(Entity.class);

Then in other class, it can inject Repository via

@Inject
Respository<Entity> entityRepository;

Usage

Basic C.R.U.D Operations

The following entity class will be assumed:

@Table(name = "customer")
public class Customer {
    @PrimaryKey(autoIncrement = true)
    @Column(name = "id")
    public Long id;

    @NotNull
    @NotBlank
    @Column(name = "email")
    public String email;

    @NotNull
    @NotBlank
    @Column(name = "first_name")
    public String firstName;

    @NotBlank
    @Column(name = "last_name")
    public String lastName;

    @NotNull
    @Column(name = "updated_time")
    public LocalDateTime updatedTime;
}

Create record

To add a new record, instantiate an entity class and assign all properties and call Repository#insert method/

Customer customer = new Customer();
customer.email = request.email;
customer.firstName = request.firstName;
customer.lastName = request.lastName;
customer.updatedTime = LocalDateTime.now();
customer.id = customerRepository.insert(customer).get();

Update record

To update a record, load the entity from db

Customer customer = customerRepository.get(id).orElseThrow(() -> new NotFoundException("customer not found, id = " + id.toString()));

or instantiate an entity class and assign primary key manually

customer.id = id;

and then update it's properties accordingly:

customer.updatedTime = LocalDateTime.now();
customer.firstName = request.firstName;
if (request.lastName != null) {
    customer.lastName = request.lastName;
}
customerRepository.update(customer);

Delete record

To delete a record simply call Repository.delete method and provide primary key value:

customerRepository.delete(id);

Query usage

core-ng supports dynamic queries through Query interface, it defines useful methods like skip(), limit(), where(), fetch() and count(), see below example:

Query<Customer> query = customerRepository.select();
query.skip(request.skip)
     .limit(request.limit);
if (!Strings.isEmpty(request.email)) {
    query.where("email = ?", request.email);
}
if (!Strings.isEmpty(request.firstName)) {
     query.where("first_name like ?", Strings.format("{}%", request.firstName));
}
if (!Strings.isEmpty(request.lastName)) {
     query.where("last_name like ?", Strings.format("{}%", request.lastName));
}
result.customers = query.fetch().stream().map(this::view).collect(Collectors.toList());
result.total = query.count();
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