How to use Middleware with CROW Blueprint

[manishjha5410]

I want to know how can i use middleware with crow_bp_route as i had seen the example of crow middleware there is a need to provide the middleware to crow:APP but is it even necessary ?

Suppose if i had 50 middleware which is separated across 10 blueprint, so mycrow app would be a lengthy very datatype so is there any way to provide middleware directly to blueprint instead of passing to crow::app.

Please answer @thedrow @gittiver

[manishjha5410]

See my whole point if we are just copying and pasting entire parameter of crow blueprint to crow app then why to use crow blueprint use crow app instead

[witcherofthorns]

Hi, yep, i agree with you, there is this slightly inconvenient thing, you constantly have to forward instance crow::app. Personally, i dont use my custom middleware for this, instead, i use simple methods declared in my middlewares.hpp (for example jwt verify), it's much more convenient 🤷‍♂️
P.s. It seems to me that this is unlikely to be corrected in any way, most likely, everything will remain as it is

[manishjha5410]

Hi what are the custom middlewares that you used can you tell me more about it

[witcherofthorns]

@manishjha5410 All the middleware I used ended with CORS or Cookie, i can’t share much experience, because basically, everything was placed in main.cpp, but if you really care, you could try defining crow app in one place, and passing it as a variable by reference

// app.hpp
#include<crow/app.h>
#include<crow/middlewares/cors.h>
#define CROW_APP crow::App<crow::CORSHandler>

well, yes, this is just an option, but it will help you not to constantly change variables everywhere if you add new middleware

[witcherofthorns]

in fact, in the working project I didn’t bother too much, everything is simple for me, I just have some kind of .hpp file that has a class/methods, and .cpp implementation files that I just call when I need it, here and that's all

// jwt.hpp
const std::string jwt_create_access(std::string uuid);
const std::string jwt_create_refresh(std::string uuid);

// jwt.cpp
const std::string jwt_create_access(std::string uuid){
    // your code
}
const std::string jwt_create_refresh(std::string uuid){
    // your code
}

// your auth route
CROW_BP_ROUTE(bp, "auth/update/access").methods(HTTPMethod::POST)([](const crow::request& req) {
    // get header (token) string from name "Refresh"
    // jwt verify your token
    // call jwt_create_access(uuid);
});

yes, I don’t use classes, because I don’t see much point in it, since everything is static anyway, and there’s actually not that much code

[witcherofthorns]

but if you want to use the middleware scheme from Сrow, you can check out this page

[manishjha5410]

Thanks for your approach but is it possible to define all the stuff in single cpp file does isnt it too chaotic personally i think it would create a mess. Okay do you know someone who can give me a glance of the crow workflow just for the middlewares if there exist no possible solution I would try to create one.

[witcherofthorns]

I don't quite understand what you mean, well, you can look at the Crow source code or all the available information on the Crow website, maybe it will help, idnt know

[manishjha5410]

Actually i was saying can someone help me for understanding the functionality of middleware, how they are link how they are used,etc in crow source code

[manishjha5410]

I will update my code accordingly

[witcherofthorns]

If middleware is used in your Route/Blueprint, then it occurs before Crow gives you the crow::req, the middleware is needed to do pre-checking, before passing along your custom route, this is just for convenience, that's all , there is no more magic here, I don’t know what else can be explained here 🤷‍♂️

[manishjha5410]

Okay so how is Crow Middleware works in crow:App how does the pre checking work didnt the middleware is called before the crow::App get the crow::req and why did @gittiver you closed this issue i had remaining some things to clear.

[gittiver]

Seems that not everything was clarified, so issue reopened.