Entitymanager merge not updating database
Make sure to use DQL to fetch-join all the parts of the object-graph that you need as efficiently as possible. By applying the persist operation on some entity, that entity becomes MANAGED, which means that its persistence is from now on managed by an Entity Manager.As a result the persistent state of such an entity will subsequently be properly synchronized with the database when method on an entity does NOT cause an immediate SQL INSERT to be issued on the database.I write articles especially for Java, Python and Asp. Doctrine does NEVER touch the public API of methods in your entityclasses (like getters and setters) nor the constructor method.You can still access the associated properties author and comments and the associated objects they contain. Instead of passing you back a real Author instance and a collection of comments Doctrine will create proxy instances for you.Only if you access these proxies for the first time they will go through the Entity Manager and load their state from the database.If you want to update the record in the table you should take the latest version record from the database and update it.
The life cycle of entities are managed in persistence context.
Instead, it uses reflection to get/set data from/to your entity objects. Take the following example, where you find an article with the headline "Hello World" with the ID 1234: In this case the Article is accessed from the entity manager twice, but modified in between.
When Doctrine fetches data from DB and saves it back, any code put in your get/set methods won't be implicitly taken into account. Their identity has a conceptual meaning inside your domain. Doctrine 2 realizes this and will only ever give you access to one instance of the Article with ID 1234, no matter how often do you retrieve it from the Entity Manager and even no matter what kind of Query method you are using (find, Repository Finder or DQL).
This lazy-loading process happens behind the scenes, hidden from your code.
See the following code: Traversing the object graph for parts that are lazy-loaded will easily trigger lots of SQL queries and will perform badly if used to heavily.So in this document we can see when this error occur and how to resolve it. In this maven file we can configure dependencies for jpa, hibernate, java, database etc. Three packages, one for entity, one for Business logic, one for Application testing.