Support for exploded query parameters

[jon-smith]

Hello, I've been using this library for rust code generation and I've found it much better than the alternatives.

However, I've ran into an issue with some openapi specs I'm using that have exploded query parameters. Is there a plan to support these?

Currently exploded query parameters map to Option<impl AsRef<str>>, with the string being added to the query directly (not 'exploded').

Here's a minimal example:

{
  "openapi": "3.0.3",
  "info": {
    "title": "Exploded Query Param Repro",
    "version": "1.0.0"
  },
  "paths": {
    "/widgets": {
      "get": {
        "operationId": "findWidgets",
        "parameters": [
          {
            "name": "filter",
            "in": "query",
            "style": "form",
            "explode": true,
            "schema": {
              "type": "object",
              "properties": {
                "color": {
                  "type": "string"
                }
              }
            }
          }
        ],
        "responses": {
          "200": {
            "description": "OK"
          }
        }
      }
    }
  }
}

This creates the rust code below:

impl HttpClient {
    /// `GET /widgets`
    pub async fn find_widgets(
        &self,
        filter: Option<impl AsRef<str>>,
    ) -> Result<(), ApiOpError<serde_json::Value>> {
        let request_url = format!("{}{}", self.base_url, "/widgets");
        let mut req = self.http_client.get(request_url);
        {
            let mut query_params: Vec<(&str, String)> = Vec::new();
            if let Some(v) = filter {
                query_params.push(("filter", v.as_ref().to_string()));
            }
            if !query_params.is_empty() {
                req = req.query(&query_params);
            }
        }
        ...

This gives a request like GET /widgets?filter=<whatever-string-the-caller-passed>, where I would expect the form GET /widgets?color=red.

With support, the generated function could be:

 pub async fn find_widgets(
        &self,
        filter:  Option<Filter>, // generated struct for the inline object schema
    ) 

or

 pub async fn find_widgets(
        &self,
        color:  Option<String>, 
        // Other params in the filter
    ) 

If this is of interest and not planned I could make a PR.

Thanks

[lightsofapollo]

Definitely want to support this- it's a breaking change for anyone upgrading the generator so It will be in 0.6.0 which I am working on now