This blog article is part of a “series of blog articles” about common pitfalls using JPA and ways to avoid them. In this article, we describe issues of EM.persist with respect to relationships.
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JPA Pitfalls (2): List or Set Relationship
This blog article is part of a “series of blog articles” about common pitfalls using JPA and ways to avoid them. In this article, we describe the difference between a set or list relationship.
Continue readingJPA Pitfalls (1): Serialized Collection
This blog article is part of a “series of blog articles” about common pitfalls using JPA and ways to avoid them. In this article, we describe, how easily a relation mapped as collection ends up as a blob.
Continue readingJPA Pitfalls – a Series of Serious JPA Obstacles
Most of our Java-based web-applications store their data in a relational database such as Oracle, PostgreSQL, MySQL, MariaDB or MS SQLServer. The standard way to access and modify the data is using an object-relational mapping as specified by the Java Persistence API (JPA). Over the years JPA has become a mature specification and there are a couple of JPA implementations with strong support such as Hibernate, EclipseLink, OpenJPA and DataNucleus. However, day-to-day project experience demonstrates there are number of pitfalls you might run into when using JPA.
To avoid stumbling into the same pitfall again and again, we collected them with their solutions and presented these pairs of problems and solutions. This is a start of a series of blog articles each describing a pitfall and a way to circumvent it.
Java Optional and Kotlin Nullable
We are using Kotlin and Spring Boot in one of our projects. This includes Spring Boot Jpa Repositories. We are using a CrudRepository that provides basic functionalities like save(), delete(), findById() etc. This library is written in Java, hence method signatures look like this:
Optional<T> findById(ID var1); Using this API out of the box would force us to deal with cumbersome Java Optionals. Since we are implementing in Kotlin we would like to use Kotlin Nullables instead and as it turned out we can achieve this very easily.
Continue readingGUI Transactions with the FRP Framework Sodium
Sodium is an implementation of Functional Reactive programming (FRP) with some nice features. One of these is the support of transactions in the GUI layer. I had quite some discussions with my colleagues on what this actually means and if such a transaction concept is useful or not. In this article I sum up my current insights and opinions about transactions in Sodium.
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Efficient Docker images for Spring Boot applications
Using fat JARs within Docker images wastes storage. I’ll demonstrate how to do better when using Spring Boot and Maven.
No more ifs – an application of functional programming in Java
Java 8 introduced with Optional a functional datatype that enables the developer to work with optional values without nested if-statements. This can simplify your code a lot.
Navigating Vaadin 8
Hurray! Vaadin 8 has finally been released and comes up with a bunch of new features. Maybe the most important one is a new data binding concept. But the feature I’m discussing here is support for the HTML5 History API.
