Crow/index.md at c5d00f784bcd5b7fd911bb95a746e72568d571c2

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A Fast and Easy to use microframework for the web.

Description

Crow is a C++ microframework for running web services. It uses routing similar to Python's Flask which makes it easy to use. It is also extremely fast, beating multiple existing C++ frameworks as well as non C++ frameworks.

Features

Easy Routing (similar to flask).
Type-safe Handlers.
Blazingly fast (see this benchmark and this benchmark).
Built in JSON support.
Mustache based templating library (crow::mustache).
Header only library (single header file available).
Middleware support for extensions.
HTTP/1.1 and Websocket support.
Multi-part request and response support.
Uses modern C++ (11/14)

Still in development

HTTP/2 support

Documentation

Available here.

Examples

Hello World

#define CROW_MAIN
#include "crow.h"

int main()
{
    crow::SimpleApp app;

    CROW_ROUTE(app, "/")([](){
        return "Hello world";
    });

    app.port(18080).multithreaded().run();
}

JSON Response

CROW_ROUTE(app, "/json")
([]{
    crow::json::wvalue x;
    x["message"] = "Hello, World!";
    return x;
});

Arguments

CROW_ROUTE(app,"/hello/<int>")
([](int count){
    if (count > 100)
        return crow::response(400);
    std::ostringstream os;
    os << count << " bottles of beer!";
    return crow::response(os.str());
});

Handler arguments type check at compile time

// Compile error with message "Handler type is mismatched with URL paramters"
CROW_ROUTE(app,"/another/<int>")
([](int a, int b){
    return crow::response(500);
});

Handling JSON Requests

CROW_ROUTE(app, "/add_json")
.methods("POST"_method)
([](const crow::request& req){
    auto x = crow::json::load(req.body);
    if (!x)
        return crow::response(400);
    int sum = x["a"].i()+x["b"].i();
    std::ostringstream os;
    os << sum;
    return crow::response{os.str()};
});

More examples can be found here.

Setting Up / Building