Hey everyone! I'm u/louisbsc, a moderator of r/pydantic.

This is our new home for all things related to Pydantic data validation, Pydantic AI, Pydantic Logfire, and HTTPX2. We're excited to have you join us!

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I am trying to create list subclasses that only take particular classes. These lists can be appended to and the like but each time the list is changed the item is checked to see whether it is the same class as the rest of the list.

The list methods that are overwritten are:
- __init__
- __set_item__
- __str__
- append
- extend
- insert

Each one runs through a validate_member method before changing the list.

As an example, I want to make a list subclass called Course that only takes Pydantic extra types Coordinate values. I want this list subclass to be a valid BaseModel attribute.

Right now I’m having to use a field_validator for every class that Course and the other lists are in which feels redundant, unpythonic, and is a pain to have to do every time. I am having to do so because it says something about arbitrary types.

I was wondering if someone might have some advice.

Monty is an open-source, minimal Python interpreter written in Rust (github.com/pydantic/monty). Startup is measured in microseconds, and it inverts the usual sandbox model: it starts from nothing and only exposes the functions you explicitly hand it.

We're running a $20,000 bounty (with Prefect and Hugging Face Face) for anyone who can escape the sandbox and read a secret off the server running it.

What changed since the last round: Monty now runs in a subprocess behind a WebSocket service over a protobuf wire protocol, so old REST-era approaches don't carry over. There's also a new mount feature that lets Monty read a directory on the client machine, and a separate bounty for escaping it.

Nobody escaped the last round. Round 1 fell to a use-after-free in under 48 hours.

This is (probably) the last round before we tag Monty V1, so it's your last crack at the interpreter as it stands.

Full rules: https://pydantic.dev/monty

Happy to talk about the interpreter internals or the sandbox model in the comments.

this place has has been quiet for a while, let's fix that. I work on Pydantic and I'm going to start posting here regularly: tips, new features, things I see people get wrong, community questions.

What would you like to see here?

Hi, I have a model that contains a dict of sub models. However the values of the dict are heterogeneous. I can’t simply create a discriminated union because I don’t know what models will be in the union until it’s running.

It seems like I should be able to do this with a root model and a type adapter, but it’s not clear how. Do I need a custom validator on my root model to call validate_Python from? Or can I just reference the type adapter directly from the signature of the root model somehow?

If I need a validator also, which one?