LuSyringe

Benefits

The main benefit is being able to separate your business code (classes) from the logic of the documentation and pydantic validation. For example, a class that serves as a response for an endpoint may look like this without LuSyringe:

class HealthResponse(BaseModel):
  ping: str = Field(..., example="pong")
  version: str = Field(..., example="1.0.0")

And that's not bad at first look, but the response class is tightly coupled of the logic of the validation + documentation offered by Pydantic and FastAPI. When dealing with inheritance, you may run into cases that the search for where the documentation is being defined is a bit harsh.

Well, with LuSyringe that's how the HealthReponse class would look.

from lusyringe import lusyringe

class HealthResponse(metaclass=lusyringe(health_response_docs)):
  ping: str
  version: str

Nice, isn't it? 🤩 . But hey, what about inheritance, what if I'm inheriting these fields from a base class, or what if this base class is inheriting these fields?

Hey, calm down. I solved all these things for you here, no need to worries 😝 , ah! I do type checking for you too, (but I also have a non-strict mode if you are adventurous) .

How it works

The usage is pretty simple 🥰 . You can define your docs object in the following manner:

from lusyringe import Prescription

health_response_docs = [
    Prescription(
        field='ping',
        type=str,
        doc=Field(..., example='Pong')
    ),
    Prescription(
        field='version',
        type=str,
        doc=Field(..., example='0.0.1')
    ),
]

Then you can pass your docs object to lusyringe, like this:

from lusyringe import lusyringe

# import your file
from ... import health_response_docs

class HealthResponse(metaclass=lusyringe(health_response_docs)):
  ping: str
  version: str

Cool, huh? I can throw some errors if you forget to define your fields in the class, or in a base class being inherited from 👮

NotImplementedError: f"Documentation for {field} with type {type_} was found,"
                     f"but field was not implemented in {class_name}"

So be a good developer and do not forget to declare your things. But hey! Remember when I called you adventurous? Yeah, I have a little surprise for you:

class HealthResponse(metaclass=lusyringe(health_response_docs, strict=False)):
  pass

What!? What does the strict mean? Well, basically I'll allow your recklessness in don't defining the fields, so I'll do it for you 🙄 . But I'll get mad if you declare something with the wrong type! So be in line.

ValueError: f"Tried to apply type {applied_type} to already defined {field}"
            f"of type {existent_type}"

Installing

Initially this will only be available for the folks at Luizalabs 😇 . But if you are from here, you can just:

pip install lusyringe

If you have our pypi