JPATag ArchiveSubscribe

FetchMode in Spring Data JPA 1. Introduction In this short tutorial, we’ll take a look at different FetchMode values we can use in the @org.hibernate.annotations.Fetch annotation. 2. Setting up the Example As an example, we’ll use the following Customer entity with just two properties – an id and a set… Continue Reading spring-data-jpa-fetchmode

Customizing the Result of JPA Queries with Aggregation Functions 1. Overview While Spring Data JPA can abstract the creation of queries to retrieve entities from the database in specific situations, we sometimes need to customize our queries, such as when we add aggregation functions. In this tutorial, we’ll focus on… Continue Reading jpa-queries-custom-result-with-aggregation-functions

Mapping a Single Entity to Multiple Tables in JPA 1. Introduction JPA makes dealing with relational database models from our Java applications less painful. Things are simple when we map every table to a single entity class. But, sometimes we have reasons to model our entities and tables differently: When… Continue Reading jpa-mapping-single-entity-to-multiple-tables

JPA Annotation for the PostgreSQL TEXT Type 1. Introduction In this quick tutorial, we’ll explain how to manage the PostgreSQL TEXT type using the annotations defined by the JPA specification. 2. The TEXT Type in PostgreSQL When working with PostgresSQL we may, periodically, need to store a string with an… Continue Reading jpa-annotation-postgresql-text-type

Default Column Values in JPA 1. Introduction In this tutorial, we’ll look into default column values in JPA. We’ll learn how to set them in as a default property in the entity as well as directly in the SQL table definition. 2. While Creating an Entity The first way to… Continue Reading jpa-default-column-values

One-to-One Relationship in JPA 1. Introduction In this tutorial, we’ll have a look at different ways of creating one-to-one mappings in JPA. We’ll need a basic understanding of the Hibernate framework, so please check out our Guide to Hibernate 5 with Spring for extra background. Further reading: Overview of JPA/Hibernate Cascade Types… Continue Reading jpa-one-to-one

Fixing the JPA error “java.lang.String cannot be cast to Ljava.lang.String;” 1. Introduction Of course, we’d never suppose that we can cast a String to a String array in Java: java.lang.String cannot be cast to [Ljava.lang.String; But, this turns out to be a common JPA error. In this quick tutorial, we’ll show how this comes… Continue Reading jpa-error-java-lang-string-cannot-be-cast

Criteria API – An Example of IN Expressions 1. Overview We often come across problems where we need to query entities based on whether a single-valued attribute is a member of a given collection. In this tutorial, we’ll learn how to solve this problem with the help of the Criteria API. 2.… Continue Reading jpa-criteria-api-in-expressions

Mapping Entitiy Class Names to SQL Table Names with JPA 1. Introduction In this short tutorial, we’ll learn how to set SQL table names using JPA. We’ll cover how JPA generates the default names and how to provide custom ones. 2. Default Table Names The JPA default table name generation… Continue Reading jpa-entity-table-names