It's so wonderful to hear about crow, a web framework to develop web application with cpp.
github.com
A exampe from offical
#include "crow.h"
int main()
{
crow::SimpleApp app;
CROW_ROUTE(app, "/")([](){
return "Hello world";
});
app.port(18080).multithreaded().run();
}
route
crow define a macro CROW_ROUTE(app, url)
#ifdef CROW_MSVC_WORKAROUND
#define CROW_ROUTE(app, url) app.route_dynamic(url)
#else
#define CROW_ROUTE(app, url) app.route(url)
#endif
params
#include "crow.h"
int main()
{
crow::SimpleApp app;
CROW_ROUTE(app, "/")([](){
return "Hello world";
});
CROW_ROUTE(app,"/hello/")
([](int count){
if (count > 100)
return crow::response(400);
std::ostringstream os;
os << count << " bottles of beer!";
return crow::response(os.str());
});
CROW_ROUTE(app, "/params")
([](const crow::request& req){
std::ostringstream os;
os << "Params: " << req.url_params << "\n\n";
os << "The key 'foo' was " << (req.url_params.get("foo") == nullptr ? "not " : "") << "found.\n";
if(req.url_params.get("pew") != nullptr) {
double countD = boost::lexical_cast(req.url_params.get("pew"));
os << "The value of 'pew' is " << countD << '\n';
}
auto count = req.url_params.get_list("count");
os << "The key 'count' contains " << count.size() << " value(s).\n";
for(const auto& countVal : count) {
os << " - " << countVal << '\n';
}
return crow::response{os.str()};
});
app.port(18080).multithreaded().run();
}
json
#include "crow.h"
int main()
{
crow::SimpleApp app;
CROW_ROUTE(app, "/json")
([]{
crow::json::wvalue x;
x["message"] = "Hello, World!";
return x;
});
app.port(18080).run();
}
header
#include "crow.h"
int main()
{
crow::SimpleApp app;
CROW_ROUTE(app, "/")
([](const crow::request& req){
std::ostringstream os;
// ci_map req.header
os << "Headers Server: " << req.get_header_value("test") << "\n\n";
return req.get_header_value("test");
});
app.port(18080).run();
}
middleware
#include "crow.h"
#include
class ExampleLogHandler : public crow::ILogHandler {
public:
void log(std::string message, crow::LogLevel level) override {
// cerr << "ExampleLogHandler -> " << message;
}
};
struct ExampleMiddleware
{
std::string message;
ExampleMiddleware()
{
message = "foo";
}
void setMessage(std::string newMsg)
{
message = newMsg;
}
struct context
{
};
void before_handle(crow::request& req, crow::response& res, context& ctx)
{
CROW_LOG_DEBUG << " - MESSAGE: " << message;
}
void after_handle(crow::request& req, crow::response& res, context& ctx)
{
// no-op
}
};
int main()
{
crow::App app;
app.get_middleware().setMessage("hello");
app.route_dynamic("/")
([]{
return "Hello World!";
});
app.route_dynamic("/about")
([](){
return "About Crow example.";
});
// a request to /path should be forwarded to /path/
app.route_dynamic("/path/")
([](){
return "Trailing slash test case..";
});
// simple json response
app.route_dynamic("/json")
([]{
crow::json::wvalue x;
x["message"] = "Hello, World!";
return x;
});
app.route_dynamic("/hello/")
([](int count){
if (count > 100)
return crow::response(400);
std::ostringstream os;
os << count << " bottles of beer!";
return crow::response(os.str());
});
app.route_dynamic("/add//")
([](const crow::request& req, crow::response& res, int a, int b){
std::ostringstream os;
os << a+b;
res.write(os.str());
res.end();
});
// Compile error with message "Handler type is mismatched with URL paramters"
//CROW_ROUTE(app,"/another/")
//([](int a, int b){
//return crow::response(500);
//});
// more json example
app.route_dynamic("/add_json")
.methods(crow::HTTPMethod::POST)
([](const crow::request& req){
auto x = crow::json::load(req.body);
if (!x)
return crow::response(400);
auto sum = x["a"].i()+x["b"].i();
std::ostringstream os;
os << sum;
return crow::response{os.str()};
});
app.route_dynamic("/params")
([](const crow::request& req){
std::ostringstream os;
os << "Params: " << req.url_params << "\n\n";
os << "The key 'foo' was " << (req.url_params.get("foo") == nullptr ? "not " : "") << "found.\n";
if(req.url_params.get("pew") != nullptr) {
double countD = boost::lexical_cast(req.url_params.get("pew"));
os << "The value of 'pew' is " << countD << '\n';
}
auto count = req.url_params.get_list("count");
os << "The key 'count' contains " << count.size() << " value(s).\n";
for(const auto& countVal : count) {
os << " - " << countVal << '\n';
}
return crow::response{os.str()};
});
// ignore all log
crow::logger::setLogLevel(crow::LogLevel::DEBUG);
//crow::logger::setHandler(std::make_shared());
app.port(18080)
.multithreaded()
.run();
}
websocket
#include "crow.h"
#include
#include
#include
using namespace std;
vector msgs;
vector> ress;
void broadcast(const string& msg)
{
msgs.push_back(msg);
crow::json::wvalue x;
x["msgs"][0] = msgs.back();
x["last"] = msgs.size();
string body = crow::json::dump(x);
for(auto p:ress)
{
auto* res = p.first;
CROW_LOG_DEBUG << res << " replied: " << body;
res->end(body);
}
ress.clear();
}
// To see how it works go on {ip}:40080 but I just got it working with external build (not directly in IDE, I guess a problem with dependency)
int main()
{
crow::SimpleApp app;
crow::mustache::set_base(".");
CROW_ROUTE(app, "/")
([]{
crow::mustache::context ctx;
return crow::mustache::load("example_chat.html").render();
});
CROW_ROUTE(app, "/logs")
([]{
CROW_LOG_INFO << "logs requested";
crow::json::wvalue x;
int start = max(0, (int)msgs.size()-100);
for(int i = start; i < (int)msgs.size(); i++)
x["msgs"][i-start] = msgs[i];
x["last"] = msgs.size();
CROW_LOG_INFO << "logs completed";
return x;
});
CROW_ROUTE(app, "/logs/")
([](const crow::request& /*req*/, crow::response& res, int after){
CROW_LOG_INFO << "logs with last " << after;
if (after < (int)msgs.size())
{
crow::json::wvalue x;
for(int i = after; i < (int)msgs.size(); i ++)
x["msgs"][i-after] = msgs[i];
x["last"] = msgs.size();
res.write(crow::json::dump(x));
res.end();
}
else
{
vector> filtered;
for(auto p : ress)
{
if (p.first->is_alive() && chrono::steady_clock::now() - p.second < chrono::seconds(30))
filtered.push_back(p);
else
p.first->end();
}
ress.swap(filtered);
ress.push_back({&res, chrono::steady_clock::now()});
CROW_LOG_DEBUG << &res << " stored " << ress.size();
}
});
CROW_ROUTE(app, "/send")
.methods("GET"_method, "POST"_method)
([](const crow::request& req)
{
CROW_LOG_INFO << "msg from client: " << req.body;
broadcast(req.body);
return "";
});
app.port(40080)
//.multithreaded()
.run();
}