lazy-initialization – Page 2

How to solve the LazyInitializationException when using JPA and Hibernate

April 23, 2023 by Tarik

Hibernate 4.1.6 finally solves this issue: https://hibernate.atlassian.net/browse/HHH-7457 You need to set the hibernate-property hibernate.enable_lazy_load_no_trans=true Here’s how to do it in Spring: <bean id=”entityManagerFactory” class=”org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean”> <property name=”dataSource” ref=”myDataSource”/> <property name=”packagesToScan” value=”com.mycompany.somepackage”/> <property name=”jpaVendorAdapter” ref=”hibernateVendorAdapter”/> <property name=”jpaDialect” ref=”jpaDialect”/> <property name=”jpaProperties”> <props> <prop key=”hibernate.enable_lazy_load_no_trans”>true</prop> </props> </property> </bean> Voila; Now you don’t have to worry about LazyInitializationException while navigating … Read more

Solve Hibernate Lazy-Init issue with hibernate.enable_lazy_load_no_trans

April 9, 2023 by Tarik

The problem with this approach is that you can have the N+1 effect. Imagine that you have the following entity: public class Person{ @OneToMany // default to lazy private List<Order> orderList; } If you have a report that returns 10K of persons, and if in this report you execute the code person.getOrderList() the JPA/Hibernate will … Read more

Lazy field initialization with lambdas

April 7, 2023 by Tarik

Within your actual lambda, you can simply update the fooField with a new lambda, such as: class A<T>{ private Supplier<T> fooField = () -> { T val = expensiveInit(); fooField = () -> val; return val; }; public T getFoo(){ return fooField.get(); } } Again this solution is not thread-safe as is the .Net Lazy<T>, … Read more

Property initializers run before ‘self’ is available

March 21, 2023 by Tarik

As correctly pointed out by vadian you should create an init in such scenarios: class MyOwn { let myUser: User var life: Int init() { self.myUser = User(name: “John”, age: 100) self.life = myUser.age } } You can’t provide a default value for a stored property that depends on another instance property.

Does .net core dependency injection support Lazy

March 20, 2023 by Tarik

Here’s another approach which supports generic registration of Lazy<T> so that any type can be resolved lazily. services.AddTransient(typeof(Lazy<>), typeof(Lazier<>)); internal class Lazier<T> : Lazy<T> where T : class { public Lazier(IServiceProvider provider) : base(() => provider.GetRequiredService<T>()) { } }

How to implement thread-safe lazy initialization?

March 1, 2023 by Tarik

For singletons there is an elegant solution by delegating the task to the JVM code for static initialization. public class Something { private Something() { } private static class LazyHolder { public static final Something INSTANCE = new Something(); } public static Something getInstance() { return LazyHolder.INSTANCE; } } see http://en.wikipedia.org/wiki/Initialization_on_demand_holder_idiom and this blog post … Read more