pydantic not working

[MominIqbal-1234]

Caused by:
ModuleNotFoundError: No module named 'pydantic_core._pydantic_core'
Error: Build command for component spin-templete failed with status Exited(1)

[dicej]

Thanks for reporting this, @MominIqbal-1234. Would you mind providing instructions for reproducing this issue?

[karthik2804]

@dicej I have reproduced it. pydantic relies on pydantic_core which has native rust code, therefore we need to get a build from wasi-wheels.

@MominIqbal-1234, Since pypi does not have builds for wasi yet you will have build it manually. There is a list of python packages with the appropriate makefiles to build to wasi at https://github.com/dicej/wasi-wheels/

The steps should be something like

git clone https://github.com/dicej/wasi-wheels/
cd wasi-wheel
make

With that step, all the packages will be built. you can then extract the pydantic_core.tar.gz and place it in your app directory. Once that is done, the app should build.

The directory structure

tree .
$ tree -L 2
.
├── README.md
├── __pycache__
│   └── app.cpython-312.pyc
├── app.py
├── app.wasm
├── pydantic_core
│   ├── __init__.py
│   ├── __pycache__
│   ├── _pydantic_core.cpython-312-wasm32-wasi.so
│   ├── _pydantic_core.pyi
│   ├── core_schema.py
│   └── py.typed
├── requirements.txt
├── spin.toml
└── venv
    ├── bin
    ├── include
    ├── lib
    └── pyvenv.cfg

I did not test a complicated example but this example compiled and I was able to run it successfully.

import datetime
from typing import Tuple
from spin_sdk.http import IncomingHandler, Request, Response

from pydantic import BaseModel

class Delivery(BaseModel):
    timestamp: datetime.datetime


class IncomingHandler(IncomingHandler):
    def handle_request(self, request: Request) -> Response:

        timestamp = datetime.datetime(2020, 1, 2, 3, 4, 5)

        m = Delivery(timestamp=timestamp)
        print(repr(m.timestamp))

        return Response(
            200,
            {"content-type": "text/plain"},
            bytes("Hello from Python!", "utf-8")
        )

[dicej]

Thanks for digging into this @karthik2804. This is a good reminder that we should start publishing pre-built artifacts for all supported packages in the wasi-wheels repo.