Tag Archives: Spring Data

Warning, the following code example is suitable for a narrow range of use cases… but it’s strangely useful. When writing tests against Spring services or controllers, we may wish to mock the DAO layer completely. This can be achieved: @MockBean private MyDao myDao; And the mock dao is then wired into our services etc. However, there are situations where we’re ...

One of the main reasons I blog is to remind myself how easily one can use software development techniques to make bad decisions. I do it myself all the time… In a recent project, I was working with Spring Data which is able to create powerful CRUD operations over data sources if you just create an interface: interface FooRepository extends ...

Databases form an integral part of computer applications. With it comes considerable amount of database operations and the corresponding code. For huge applications which have large number of tables/entities, these operations or the code is repeated and duplicated to a large extent. Eventually a programmer would like to reduce this duplicate code. Spring framework took up the challenge and provided ...

Previously we set up two EntityManagers in the same application. One for the reads and one for the writes. Now it’s time to create our read repository. The read only repository will use the secondary read only EntityManager. In order to make it a read only repository, it is essential not to have any save and persist actions. 01 02 ...

Our previous setup works as expected. What we shall do now is to get one step further and configure two separate entity managers without affecting the functionality we achieved previously. The first step would be to set the default entity manager configuration to a primary one.This is the first step 01 02 03 04 05 06 07 08 09 10 ...

In our previous post we set up multiple PostgreSQL instances with the same data.Our next step would be to configure our spring project by using the both servers. As stated previously we shall use some of the code taken from the Spring Boot JPA post, since we use exactly the same database. This shall be our gradle build file 01 ...

This is a series of blog posts on our quest to increase our application’s performance by utilizing read replicas. For this project our goal is to set up our spring data application and use read repositories for writes and repositories based on read replicas for reads. In order to simulate this environment we shall use PostgreSQL instances through Docker. The ...

I have recently written several posts about Kotlin’s delegation. In doing so, I realised a useful way to apply it to Spring Data repositories. Which would allow Spring Data to continue sprinkling some magic while providing a route for customisation. The code shown in this post is in Kotlin, but is still relevant to Java. This post uses R2DBC, but ...

This post details a naive implementation of streaming updates from a database to any other components that are interested in that data. More precisely, how to alter a Spring Data R2DBC repository to emit events to relevant subscribers. A little bit of background knowledge of R2DBC and Spring will be helpful for this post. My previous writings, Asynchronous RDBMS access ...