MapStruct VS config

Currently using .NET and ASP.NET for the API of a project that I'm working on, overall it's a pretty lovely experience, especially with the JetBrains Rider as my IDE. Having worked with Java in the enterprise in the past, it feels like a more focused and sometimes more coherent experience (vs the more decentralized nature of Java), that now thankfully runs fine on Linux as well, don't even need to hope that Mono is good enough anymore.

Entity Framework Core is great, the way how they fetch related data is straightforwards: https://learn.microsoft.com/en-us/ef/core/querying/related-d...

I also really like the ability to use split queries, when needed: https://learn.microsoft.com/en-us/ef/core/querying/single-sp...

You can even scaffold your entity mappings from an existing database and manage database migrations separately (which I feel is a must unless you want to pour hours upon hours into learning yet another JPA-like), it's nice when something like that exists in a given ecosystem: https://blog.jetbrains.com/dotnet/2022/01/31/entity-framewor...

Some of the stuff in the ecosystem is also really nice, like using ActionBlocks from Dataflow for simple queues and task scheduling is very easy to get started with and pretty pleasant: https://learn.microsoft.com/en-us/dotnet/api/system.threadin...

Honestly, most of the docs that I've come across are rather pleasant and there's plenty of code examples to be had and even LLMs have enough codebases out there to be trained on and give decent output, in addition to the regular autocomplete in the IDE.

Even some third party stuff like CsvHelper is really well put together: https://joshclose.github.io/CsvHelper/getting-started/#insta...

That said, I've had issues where trying to deserialize incoming JSON requests ([FromBody]) lead to the whole object being null, due to it not matching the fields 1:1 or violating some nullability constraint, however that happened without a clear error message or as much as a warning in the logs, which felt insane and wasn't very discoverable. Now I just use JObject as the parameter and deserialize at the top of the controller method.

I've also run into some ecosystem issues where the OpenAPI codegen was a bit lacking and wouldn't actually generate code that works, but maybe that's because the spec was bad: https://openapi-generator.tech/docs/generators/csharp

I could also not get AutoMapper (https://docs.automapper.org/en/stable/index.html) working satisfactorily, so for now I'm stuck writing mappers by hand with said autocomplete sometimes doing it for me. There were issues with the runtime being unable to register the mappers or something like that, it was a while ago. Overall it felt like the MapStruct library in Java did everything better: https://mapstruct.org/

On the other hand, I haven't had any of the Spring Boot DI related headaches (needing @Lazy sometimes) with ASP.NET, things there seem way more straightforwards and you clearly define whether something should be a Singleton or Scoped and the rest... just gets out of your way and works.

Sadly, there have been very hard to track down cases where I try to do a _dbContext.Add(someEntity) and then when I do a save with just the fields in that one entity changed, the performance absolutely seems to slow down to a crawl. Adding _dbContext.ChangeTracker.AutoDetectChangesEnabled = false seemed to help, but I am still not entirely sure what lead to that behavior, the temp directory on my Linux box also started filling up very rapidly, yet the logs had nothing of use, definitely seems like something I'd need to investigate properly.

Overall, .NET and its ecosystem is pretty good in most cases. And .NET being used in gamedev is also cool, for those who care about that sort of thing, I wonder why jMonkeyEngine never really took off.

In Java (woof..) we have MapStruct (https://mapstruct.org/). Anything like that in Python? I think maybe the Sqlalchemy mapping in Litestar2 is the closest I've seen.

Done right i can look something like mapstruct for example. But like any other feature you need to get a feeling for when it's a good idea to use it.

We are using mapstruct but it sucks when you have protobuf :/

You all beat me to MapStruct and Testcontainers. Honorable mention to RxJava, which I use in Desktop apps.

For the mapping, I'm using Mapstruct, I got the instance example from their examples they use INSTANCE as constant.

Now update your code so that no entities are passed to/from the domain layer and that no objects are passed to/from the domain layer. You'll look at me as though I'm nuts, but you will thank me later. Look at things like http://immutables.github.io/ and https://mapstruct.org/

When my pairing partner and I ran into this use case, we were initially stumped. Even our combined Google Fu efforts were not turning up a good solution. However, we eventually discovered a PR for MapStruct that seemed to be the solution to our issues! But, of course, if it were that simple, I would not be writing this now. The SubClassMapping annotation provided by that PR, while quite helpful, requires specific Mapping annotations for every field on the subclass. We wanted a more elegant solution.

Just use MapStruct...

I don‘t understand why HOCON (https://github.com/lightbend/config/blob/main/HOCON.md) isn‘t used more often (at least for configuration use cases). It‘s a superset of JSON, has comments, multiline strings, optional quotes, replacement syntax. We use it at many places, and it‘s as nice at it can get.

HOCON is a great human-readable alternative to JSON. It's a superset of JSON with lots of cool features that make it both more readable and easier to use.

Here's a rundown of HOCON's main features: https://github.com/lightbend/config#features-of-hocon

"Typesafe Config" is the library generally used to read configuration files in HOCON format, which this library introduced. It's commonly used in essentially OOP/imperative Scala contexts, including Akka and its ecosystem.

Interesting!

For my own servers I use an internal tool that integrates apps with systemd. You point it at the output of your build system and a config file, and it produces a deb that contains systemd unit files and which registers/starts the server on install/reboot/upgrade, as a regular debian package would. Then it uploads it to the server via sftp and installs it using apt, so dependencies are resolved. As part of the build process it can download and bundle language runtimes (I use it with a JVM), it scans native binaries to find packages that the app should depend on, and you can define your config including package metadata like dependencies and systemd units using the HOCON language [1].

Upshot is you can go from a Gradle or Maven build to a running server with a few lines of config. Oh and it can build debs from any OS, so you can push from macOS and Windows too. If your server needs to depend on e.g. Postgres, you just add that dependency in your config and it'll be up and running after the push.

It also has features to turn on DynamicUser and other sandboxing features. I think I'll experiment with socket activation next, and then bundled BorgBackup.

Net/net it's pretty nice. I haven't tried with containers because many language ecosystems don't seem to really need them for many use cases. If your build tool knows how to download your language runtime and bundle it sans container by just setting up paths correctly, then going without means you can rely on your Linux distribution to keep things up to date with security patches in the background, it means networking works as you'd expect (no accidentally opened firewall ports!) and so on. SystemD knows how to configure resource isolation/cgroups and kernel sandboxing, so if you need those you can just write that into your build config and it's done. Or not, as you wish.

With a deployment tool to automate builds/pushes, systemd to supervise processes and a big beefy dedicated machine to let you scale up, I wonder how much value the container part is really still providing if you don't need the full functionality of Kubernetes.

[1] https://github.com/lightbend/config/blob/main/HOCON.md

Other similar standards: TOML, HOCON

I've also used HOCON pretty extensively for config, and it is better than both YAML and JSON for config with moderate to high complexity.