Options Request - How to Setup

[paul-marquick]

Drogon is amazing, thank you for this.

I'm struggling to get OPTIONS request handling to work. I tried to set up an OPTIONS method using ADD_METHOD_TO similar to other methods, but I couldn't get it to work. Looking at the source code I see OPTIONS seems to be handled by the system / done automatically perhaps.
However, after studying the related source code, I'm still unable to work out how to set up an OPTIONS request.
Does anyone know how to get it to work or where I can find some more information?
Also, when viewing the source code I noticed that CORS seems to be related to the OPTIONS code, please could I have some information about the CORS set up too.

Thank you.

[alwaysvitorious]

Hi Paul.
I found the best solution to manage all OPTIONS requests from main.cc:

drogon::app()
        .registerPreRoutingAdvice(
            [](const drogon::HttpRequestPtr &req, drogon::FilterCallback &&stop,
               drogon::FilterChainCallback &&pass)
            {
              if (!req->path().starts_with("/api") ||
                  req->method() != drogon::Options)
              {
                pass();
                return;
              }

              auto resp = drogon::HttpResponse::newHttpResponse();
              resp->addHeader("Access-Control-Allow-Origin", "*");
              stop(resp);
            })
        .registerPostHandlingAdvice(
            [](const drogon::HttpRequestPtr &req,
               const drogon::HttpResponsePtr &resp)
            { resp->addHeader("Access-Control-Allow-Origin", "*"); });

Instead of registerPostHandlingAdvice you can also add the response headers to each individual response. If you need credentials remember to add them and set headers as needed.
From the blog of one of the maintainers:
https://clehaxze.tw/gemlog/2024/03-02-cors-on-the-drogon-web-framework.gmi
https://web.archive.org/web/20240420234225/https://clehaxze.tw/gemlog/2024/03-02-cors-on-the-drogon-web-framework.gmi

[paul-marquick]

Hi alwaysvitorious.

Thank you for this answer. I'm grateful for your time and effort. I have it working now and have learnt more about Drogon.

Many thanks
Paul.