pojo | dependency injection manager designed for Plain Old | Dependency Injection library

I have quite a few projects that is slowly being migrated from Java to Kotlin, but I'm facing a problem when changing from Java POJO to Kotlin data classes. Bean validation stops working in REST controllers. I have created a very simple project directly from https://start.spring.io to demonstrate the failure.

Many years of using Scala and still I don't know the right way to interoperate with Java. :(

To be honest, this is not something that I'm doing every day, but sometimes there is no other option (today is Firestore Java libraries).

My question today is about the proper way to instantiate POJOs that can have null values. At the end of the day, I always use something like the def toJavaLong(l: Option[Long]): java.lang.Long = if (l.isEmpty) l.get else null, but pretty sure that there is a better and elegant way.

Please, could you show me the path? I expect something like orNull working out of the box, but it is never the case.

I'm using Scala 2.13, but feel free to show alternatives to Scala 3 as well.

In the next example, I explain the errors that I have using orNull and getOrElse:

Pojo:

I have JSON like below

I am trying to use firebase-server-timestamp to show the user when he/she send their order to us.

The problem I encounter is, that the server-timestamp is showing a wrong time (e.g: Current time is 12:30, but timestamp shows 12:15). How is that possible?

I have a controller that accepts ObjectNode as @RequestBody.

That ObjectNode represents json with some user data

Given below code snippet, for each field of POJO class, is there a way to check if the type is an integer list or not? The real problem here is the type argument, since it's quite easy to check if it's a list via instanceof or isAssignableFrom.

Lines in main is what I have found so far, but it does not work for those types with more complex class hierarchy.

I've used Jackson for years, and I am not sure I ever faced this issue.

Using Jackson 2.12.5 in a Spring Boot 2.5.5 project, I have an object that I need to serialize. I have no issue with other fields, but these 2 fields are causing me problems :

Since onSaveInstanceState & onRestoreInstanceState can't be used to store/restore values after closed the app, I tried to use dataStore to solve it, but it dosen't work, here's my trying

DataStoreRepository

This question is somehow related to my last question, because it is the same project but now I am trying to go one more step forward.

So, in my previous question I only had one table; this time I have two tables: the new second table is supposed to contain related attributes for the rows of the first table, in a OneToMany relationship. So, I store a ForeignKey in the second table that would store the Row ID of the first table's related row (obviously).

The problem is this: the intention is creating both registers (parent and child) at the same time, using the same form, and ParentTable uses AUTO_INCREMENT for his PrimaryKey (AKA ID).

Due to how RoomDb works, I do the creation using a POJO: but after insertion, this POJO won't give me the auto-generated ID as far as I know... so, the only workaround I am able to imagine is, when submitting the form, first make the INSERT for the parent, then using one of the form's fields that created the parent to make some kind of "SELECT * FROM parent_table WHERE field1 LIKE :field1", retrieving the ID, and then use that ID to create the child table's POJO and perform the next INSERT operation. However I feel something's not right about this approach, the last time I implemented something similar this way I ended up with a lot of Custom Listeners and a callback hell (I still have nightmares about that).

About the Custom Listeners thing, it is the solution I ended up choosing for a different problem for a different project (more details about it in this old question). Taking a look to that old question might help adding some context about how misguided I am in MVVM's architecture. However, please notice the current question has nothing to do with WebServices, because the Database is purely local in the phone's app, no external sources.

However, I am wondering: isn't this overkill (I mean the INSERT parent -> SELECT parentID -> INSERT child thing)? Is it inevitable having to do it this way, or there is rather a more clean way to do so?

The "create method" in my Repository class looks like this: