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 with bidirectional relationships.
Continue readingJPA Pitfalls (3): Cascade Persist
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.
Continue readingJPA 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.
Developers Adopt Kotlin! Addressing your fears and Kotlin’s gains.
Every time I have used Kotlin instead of Java I enjoyed it and did not regret it. But somehow I still meet some reservations regarding Kotlin with both managers and sometimes developers.
This Post will address your fears as a (Java) developer regarding the use of Kotlin and elaborate a bit on what Kotlin will gain you. There is a similar post on this blog addressing managers (German version here) which will probably also be good reading for you.
Managers adopt Kotlin! Addressing your fears and Kotlin’s gains.
Every time I have used Kotlin instead of Java I enjoyed it and did not regret it. But somehow I still meet some reservations regarding Kotlin with both managers and sometimes developers.
This post will address your fears as a manager regarding the use of Kotlin and elaborate a bit on what Kotlin will gain you. There will be a similar post on this blog addressing developers that goes a bit more into technical details.
Angular & OpenId: a real world example
In theory it appears pretty easy to build the browser side of an application using OpenId Connect. Actually implementing it in a real world application has usually proven to be more difficult than that.
I would like to show you how to solve some of the real world problems beside the basic setup. First let me describe what I want to build:
- a single page app with Angular
- routing via the hash part of the url
- a forced login via OIDC
I will write about the following problems within building that app:
- What library to choose?
- Where and when to initialise that library?
- Angular and hash based routing
- How to handle errors?
- Some smaller miscellaneous problems
Part 1: GraphQL with Spring Boot, JPA and Kotlin
GraphQL is a query language for dynamic queries on linked data. In the GraphQL world, there are many tutorials and documentation that illustrate the concrete introduction to GraphQL. Since getting started requires a lot of explanation, regular tutorials usually have a simple setup, which does not reflect the real world complexity. If additional technologies are added or the complexity of the project increases, these “Hello World” examples are usually no longer so helpful.
This article introduces GraphQL on the technology Spring Boot with JPA and Kotlin. I also present some best practices which I have learned while I have worked with it. You can find the source code here: https://github.com/akquinet/kotlin-spring-graphql
Continue reading