Overly Broad Type Generated When Using "const"

Got a little nit in the type generation.

When I have a type in the OpenAPI schema that uses "const" like this:

"ConstModifier": {
    "type": "object",
    "properties": {
        "someConstant": {
            "type": "string",
            "const": "TheOnlyValidValue"
        },
    },
}

I get the following rust code:

#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct ConstModifier {
    #[serde(rename = "someConstant", skip_serializing_if = "Option::is_none")]
    pub some_constant: Option<String>,
}

The good news is that this works, in that I can call my API this way, but I'd expect it to be more tightly constrained. Rust doesn't have literal values the way Python or TS does and I'm not sure how other Rust libraries handle this... I imagine the better thing would be to emit an enum with only one option, so I'd end up constructing it something like:

let myModifier = ConstModifier {
   some_constant: Some(ConstModifierSomeConstantType::TheOnlyValidValue),
};

It certainly makes sense in our case (where the constant is a placeholder for expanding into an enum).

hrrm I'll take a look and see what I can come up with

Merge pull request #12 from gpu-cli/fix/issue-10-const-only-property

Awesome! I like it. It looks like this solved the issue for schemas, but not for when the "const" variable is used directly as an argument for an endpoint/operation. For instance, in "paths":

"/some/const/path/{the_constant}": {
    "get": {
        "summary": "DoSomeConstOperation",
        "operationId": "SomeConstOperation",
        "parameters": [
            {
                "name": "the_constant",
                "in": "path",
                "schema": {
                    "type": "string",
                    "const": "MyConstantValue"
                },
                "required": true,
            },
        ],
        "responses": {
            "200": {
                "description": "Success",
                "content": {
                    "application/json": {}
                }
            }
        }
    }
}

Generates this function signature:

pub async fn some_const_operation(
    &self,
    the_constant: impl AsRef<str>,
) -> Result<(), ApiOpError<serde_json::Value>> {
   // ... Stuff
}

Oh interesting- TBH I didn't realize that was an option lol ... Looking now

#13 fixes this

Nice! Thank you!

And I did say the API we're targeting is a little pathological 😅, haha...

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Overly Broad Type Generated When Using `"const"` #10

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Overly Broad Type Generated When Using "const" #10

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lightsofapollo commented on May 7, 2026

atom-mfeldkamp commented on May 8, 2026

lightsofapollo commented on May 8, 2026

lightsofapollo commented on May 8, 2026

atom-mfeldkamp commented on May 8, 2026

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Overly Broad Type Generated When Using `"const"` #10