RxJS Observable You have learned about the basics of Observables and Observers in the RxJS Building Blocks tutorial. In this article, I will discuss the various ways of creating Observables in rxjs and its technical details. As you know, the observable$ represents a lazy push-based collection. This can be a collection of any data or stream of events depending upon [...]
I mentioned the core components of RxJS in the introduction of RxJS page. As you know, the components are Observables, Observers, Operators, Subjects and Schedulers. These core components are nothing but the Building Blocks of RxjS. In this tutorial, you will learn how they work together to provide a powerful set of functionalities. Once you have a high-level understanding of [...]
Composite primary keys (Composite Identifier) typically used when mapping from legacy databases, where the primary key is comprised of several columns. In JPA, you have to make use of either of @EmbeddedId and @IdClass annotations to denote composite keys. Composite Identifiers are also known as Derived identities.
This is an advanced JPA tutorial with hibernate 5.x. JPA stands for Java Persistence API. It is the official java specification to work with an ORM tool. Learn JPA 2.2 with Hibernate 5.x in the right way and with a lot of code examples. Prerequisites Programming knowledge in Java.Basic knowledge of JDBC programming.JDK 8 installed on your system.Apache Maven 3.3 [...]
Advanced Docker tutorial is a complete docker tutorial with examples. This is a Zero to Hero series, to make you up and running with docker. I have created this tutorial to give you an in-depth understanding of docker and docker-compose. Docker provides a consistent way to develop, package, ship and run an application on almost any platform. You will learn [...]
Maven Tutorial - A complete tutorial with code examples. This tutorial is an advanced maven tutorial meant to make you a Hero in Apache maven. Apache Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project’s build, reporting, and documentation from a central piece of information. [...]
There are several ways JPA/Hibernate can generate primary keys for your entities. Remember, primary keys can be generated using one of the available 4 strategies. It is always advisable to use GenerationType.AUTO or GenerationType.SEQUENCE.
JPA must be annotated with @Entity and its id field should be annotated with @Id. There are several other optional annotations available, they will be discussed as part of Entity Mapping. JPA annotations can be placed on fields and/or on properties (getter/setter). You will learn Access Type in details in this section.
n object that hibernate/JPA can persist in the database and retrieve it back whenever needed is called an Entity. JPA manages various states of these entities. There are 4 states of an Object in JPA and these are New (Transient), Persistent (Managed), Detached (Unmanaged) and Removed (deleted).