Support for frozen dataclasses

[Sheemap]

Is your feature request related to a problem? Please describe.
Not really a problem per say. But many of our current models are frozen dataclasses. We try to keep them immutable by default. But unfortunately theres not a flag for it when generating through this tool.

We will probably still explore generating these just as not frozen to start, so not really a blocker. But it would be awesome if we could bring that in soon.

Describe the solution you'd like
It seems like it would be straightforward to utilize the already available --enable-faux-immutability flag.

Describe alternatives you've considered
Could add another flag of --frozen-dataclasses or similar.

Additional context
Nothin that I can think of. If I have time I will try to get a PR up if desired :)

[Iddodo]

My team could also use the addition of such feature (more in the context of Pydantic dataclasses, but I suspect that those would be related).

[JakeSummers]

Hey @Sheemap and @Iddodo ,

I am curious what you are trying to do.

When I generate PydanticV2 models, with the --enable-faux-immutability flag, I get frozen dataclasses:

class MyTHing(BaseModel):
    model_config = ConfigDict(
        extra="allow",
        frozen=True,
    )
    ...

[Sheemap]

Hi @JakeSummers, In this case specifically we're talking about python's dataclasses module. Which you can generate by passing --output-model-type dataclasses.dataclass. Which gives you this

@dataclass
class MyTHing:
    ...

Theres a frozen param you can pass to the decorator to lock all the fields, making it immutable. But datamodel-code-generator doesn't support this currently.

@dataclass(frozen=True)
class MyTHing:
    ...

This second one is what I'm specifically trying to accomplish

[koxudaxi]

@Sheemap
Thank you for bringing this up! I completely agree that having frozen dataclasses would be really useful. We have many users who prefer immutable data structures, so this would be a great addition. When you have time, feel free to submit a PR - either leveraging the existing flag or adding a new one. I'd be happy to review and help get it merged.