Did you know that you can return a boolean value from a Spring Data JPA query? For instance, you may want to know whether or not an entity (i.e. database row) exists with a given value for a field. Surely one could simply return the row count and check if it is larger than zero, but… read more
With object-relational mapping (ORM) tools such as Hibernate, one usually modifies entities by first fetching them from the database, modifying some fields, and then persisting the entities again. This is a good approach in many cases, but in some scenarios this may not be desirable. For instance, if you want to update a collection of entities (i.e.… read more
I recently had a problem with one of my Spring Data JPA queries; for some reason, I was getting the following exception. query specified join fetching, but the owner of the fetched association was not present in the select list This seemed strange, because I had written a standard JPQL/HQL query that I knew worked.… read more
This is going to be a quick one. I just want to show you how one can define a bean in Spring Framework for multiple profiles. That is, the bean will be “active” if the active profile is one in a given list. This is for example useful if you want different beans to be available at… read more
Need to pass a date as a java.util.Date instance in a Spring MVC controller action? Then you have come to the right place. You might have tried the below approach and encountered a good old 404 Not Found error. @Controller public class CompanyController { @RequestMapping("/company/added-since/{since}") public String showAddedSince(@PathVariable("since") Date since) { return "companies-added-since"; } }… read more
If you are trying to bind a Spring MVC form to a bean, then you might have come across the below exception. Neither BindingResult nor plain target object for bean name ‘mybean’ available as request attribute Some tutorials claim that you can do like this: @Controller public class PersonController { @RequestMapping(value = "/person/add", method =… read more
Sometimes you may want to return an empty JSON object from a Spring Framework controller action, be it in a REST API or just a regular controller action. This could for example be the case if you are issuing an AJAX request from jQuery; if you specify the data type to be JSON, the success handler… read more