Message param type design, why no default value for role in ChatCompletionSystemMessageParam?

[antont]

Hi, just wondering, types like ChatCompletionSystemMessageParam might be useful for creating messages benefiting from the strong types provided using Pydantic.

However, even pre-defined values don't have default values there, which kind of defeats the purpose.

I mean, it might be nice to say:

    messages_param = ChatCompletionSystemMessageParam(
        content="You are a helpful assistant."
    )

But that does not work, because the role does not have a default value, even though it is defined as a literal:

    role: Required[Literal["system"]]

Is this intentional, or perhaps an oversight wrt to how Pydantic 2 work? There that constant like field could be set to have a default value, or it could be a ClassVar, to have it there automatically. The default value would be like:

    role: Required[Literal["system"]] = "system"

[antont]

Ah I just learned the answer, when tried to subclass and fix this for myself: it's actually a TypedDict, not a Pydantic type, so it can't have default values like that.

[antont]

Ok so TypedDict does not work like that, so am using this. I guess the reason for TypedDict vs. Pydantic there is that people are used to writing dict literals with strings.

#class SystemMessage(ChatCompletionSystemMessageParam):
#    role: Required[Literal["system"]] = "system"
def system_message(content: str):
    return ChatCompletionSystemMessageParam(
        content=content,
        role="system"
    )

def user_message(content: str):
    return ChatCompletionUserMessageParam(
        content=content,
        role="user"
    )

[RobertCraigie]

Yes, if request params were also pydantic models then you would have to import a type whenever you needed to define a nested param type which we think would be annoyingly cumbersome.