Serializing @property

Question

• OS: Linux(Ubuntu 18)
• Python version 3.7.4 (tags/v3.7.4:e09359112e, Jul 8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)]
• Pydantic version 1.0

I’ve pored over the documentation and issue and can’t seem to find an example for serializing members other than class attributes.

class Rectangle(BaseModel):
    width: int
    length: int

    @property
    def area(self) -> int:
        return self.width * self.length

r = Rectangle(width=10, length=5)

print(r.json())

# What I'd like to see:
{ "width": 10, "length": 5, "area": 50 }

I’d also think that properties without setters would default to readOnly on the schema side as well.

It did seem there was a way to get something close to what I’m after via ORM mode and masking a property on the ORM model, but I’d hate to need to create a class just to contain properties.

Going over BaseModel._calculate_keys it seems BaseModel will not yield what I’m after.

Still, I’m hoping that it’s just been a long day and I overlooked something 😃

[bradodarb]

I wonder if implementing something like the schema/field as a decorator would be a good approach?

class Rectangle(BaseModel):
    width: bool
    length: int

    @property
    @field(title='Area')
    def area(self) -> int:
        return self.width * self.length

And on init, the internal fields dict could grab attributes that have the decorator and act accordingly.

I’d say the property above would set to readOnly on the schema output.

Could possibly used on methods to support writeOnly ?

I’d be happy to get a PR going with some guidance if this feature is desired by others (esp the property serializtion, not so much the method)

[PrettyWood]

Hey everyone I took some time to work again on computed fields to add some validation and also support the syntax suggested by @JosXa. You can have a full example of what’s possible in the description of #2625 or in the doc that I just wrote. I’m really looking for feedback. Since Samuel is currently overwhelmed, the more it’s tested and approved beforehand the more confident we can be when the review is done. Have a great weekend! Thanks 🙏