[BUG] file uploads not supported by the Rust generator

[qrilka]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

It's not clear how the project documents file upload support. But according to https://openapi-generator.tech/docs/generators/rust/ both File data type and FormMultipart are implemented. In practice the generated code contains just a TODO.
Side comment: file parameter becomes encoded as file: std::path::PathBuf which makes it impossible to use the generated code from WASM.

openapi-generator version

$ openapi-generator-cli --version
openapi-generator-cli 7.0.1

Also checked the latest templates in master

OpenAPI declaration file content or url

            "UploadRequest": {
                "properties": {
                    "file": {
                        "format": "binary",
                        "type": "string"
                    }
                },
                "required": [
                    "file"
                ],
                "type": "object"
            }

Generation Details

In the generated Rust code I see

    // TODO: support file upload for 'file' parameter

Reflecting the template

openapi-generator/modules/openapi-generator/src/main/resources/rust/reqwest/api.mustache

Line 269 in 783e68c

// TODO: support file upload for '{{{baseName}}}' parameter

Steps to reproduce

Create an endpoint with response body with "content": "multipart/form-data" and containing file parameter with format "binary", and type "string. Run Rust generator for this API spec.

Related issues/PRs

#16167

Suggest a fix

Create an explicit ticket about file support implementation and make it visible on the website that it's still missing.

[skyl]

Here is a spec that show the problem if it would be helpful
openapi.json

I have no idea if this might be helpful but it's what copilot says in the interface about that TODO line:

{{#supportAsync}}
let mut local_var_form = reqwest::multipart::Form::new();
{{#formParams}}
{{#isFile}}
if let Some(local_var_file_path) = {{{paramName}}} {
    match tokio::fs::File::open(local_var_file_path).await {
        Ok(file) => {
            let form_part = reqwest::multipart::Part::stream(file);
            local_var_form = local_var_form.part("{{{baseName}}}", form_part);
        },
        Err(err) => {
            return Err(Error::FileOpenError(err));
        }
    }
}
{{/isFile}}
{{/formParams}}
local_var_req_builder = local_var_req_builder.multipart(local_var_form);
{{/supportAsync}}

This is still a problem on 7.9.0 but I haven't tried main.

[vincent-herlemont]

For the implementation of this issue, what interface should we have?

• Should we keep the file path as input and read the file inside the function?
• Or should we pass a stream reader directly as a parameter?

[fage88]

Stream reader would be my preference

[wing328]

Should we keep the file path as input and read the file inside the function?

that's what i prefer as it will be a backward compatible change. otherwise, we will need an option for fallback.

[vincent-herlemont]

@wing328 Thanks for the guidance, I have started a PR here: #20242.