Allow computed fields (and methods) to be provided with `create_model()`

[Viicos]

Initial Checks

• [x] I have searched Google & GitHub for similar requests and couldn't find anything
• [x] I have read and followed the docs and still think this feature is missing

Description

As per https://github.com/pydantic/pydantic/issues/11708 and https://github.com/pydantic/pydantic/discussions/7760.

Affected Components

• [ ] Compatibility between releases
• [ ] Data validation/parsing
• [ ] Data serialization - .model_dump() and .model_dump_json()
• [ ] JSON Schema
• [ ] Dataclasses
• [ ] Model Config
• [ ] Field Types - adding or changing a particular data type
• [ ] Function validation decorator
• [ ] Generic Models
• [ ] Other Model behaviour - model_construct(), pickling, private attributes, ORM mode
• [ ] Plugins and integration with other tools - mypy, FastAPI, python-devtools, Hypothesis, VS Code, PyCharm, etc.

[karta9821]

@Viicos

Hi, I did some additional investigation.

After the change pydantic/pydantic#11032, which caused the issue, it turns out that PydanticDescriptorProxy objects are now stored in __annotations__.

As a result, it's no longer possible to iterate over them during the DecoratorInfos.build call. Hope this helps a bit ;)

[esad-pomelo]

I just ran into this. Did anyone come up with a hotfix that worked for them?

[commonism]

A possible fix - make the annotation declaration optional:

https://github.com/pydantic/pydantic/blob/2e7cddb6a7600311c4a29763efd55596a826edde/pydantic/main.py#L1742-L1746

     annotations[f_name] = f_def[0] 
     fields[f_name] = f_def[1] 
 else: 
     annotations[f_name] = f_def 

            if f_def[0]:
                annotations[f_name] = f_def[0]
            fields[f_name] = f_def[1]
        else:
            annotations[f_name] = f_def

I've copied create_model to include this.

https://github.com/commonism/aiopenapi3/blob/167c51068c8a59126d03ab3193d72d610d3dcbd9/aiopenapi3/pydanticv2.py#L38-L116

It defines fields without annotation instead of using None as annotation. I use it for properties.

[Viicos]

As a workaround that can be used with the current create_model() function, anything can be passed to __validators__ (it is used directly to update the class namespace).

I think we'll add a new parameter (something like __namespace_updates__ or similar), and we may deprecate __validators__ in favor of this one.

[commonism]

As it's too late for 2.12, any chance for 2.13?