Poem openapi Option<T> ToJSON & Type implementation mismatch

[Nahuel-M]

The ToJSON for an Option<T> is implemented as follows:

impl<T: ToJSON> ToJSON for Option<T> {
    fn to_json(&self) -> Option<Value> {
        match self {
            Some(value) => value.to_json(),
            None => Some(Value::Null),
        }
    }
}

This means { variable: null } is returned if it is a None in Rust.
However, the implementation of the Type trait for Option<T> simply passes all implementations to T, except for IS_REQUIRED, which is set to false. For example:

struct Test{
    field1: Option<String>,
}

leads to the following openapi spec:

"Test": {
        "type": "object",
        "required": [
        ],
        "properties": {
          "field1": {
            "type": "string"
          },
        }
      },

I believe this is a mismatch. The generated openapi spec suggests the field field1 either IS there and is a string, or isn't there at all, but the ToJSON impl will ensure the field is always there, but is possibly null.

As far as I can see there's two options (heh) here:

• Use the nullable annotation for options in the openapi spec
• Don't return Value::Null in the ToJSON impl of Option<T>, but return None

I'm interested in your thoughts!