ar2015 ar2015 - 3 months ago 20
Ajax Question

Ajax Json path not found

I am not bad in C++ but I have a terrible knowledge about web so please consider that the answer to this question will be simple.

I have found a C++ library for a webserver here on github.

It works fine when I enter http://localhost:8080/ in my browser to test its HTML page. I also have tested:

http://localhost:8080/info
http://localhost:8080/match/8796


They work fine too.

However, when I try to test its Ajax/Json, it does not work for me using the following code in my firefox browser console.

$.post( "json", {firstName: "John",lastName: "Smith",age: 25} );



not well-formed json:1:18 ---> Could not open path /json


I tried

$.post( "string", {firstName: "John",lastName: "Smith",age: 25} );


and received similar result.

Where am I doing mistake?




The C++ code in short, hosts a server on port 8080, responds to

server.resource["^/string$"]["POST"]
server.resource["^/json$"]["POST"]
server.resource["^/info$"]["GET"]
server.resource["^/work$"]["GET"]
server.default_resource["GET"]


The client examples are:

//Client examples
HttpClient client("localhost:8080");
auto r1=client.request("GET", "/match/123");
cout << r1->content.rdbuf() << endl;

string json_string="{\"firstName\": \"John\",\"lastName\": \"Smith\",\"age\": 25}";
auto r2=client.request("POST", "/string", json_string);
cout << r2->content.rdbuf() << endl;

auto r3=client.request("POST", "/json", json_string);
cout << r3->content.rdbuf() << endl;





http_examples.cpp [link]

#include "server_http.hpp"
#include "client_http.hpp"

//Added for the json-example
#define BOOST_SPIRIT_THREADSAFE
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>

//Added for the default_resource example
#include <fstream>
#include <boost/filesystem.hpp>
#include <vector>
#include <algorithm>

using namespace std;
//Added for the json-example:
using namespace boost::property_tree;

typedef SimpleWeb::Server<SimpleWeb::HTTP> HttpServer;
typedef SimpleWeb::Client<SimpleWeb::HTTP> HttpClient;

//Added for the default_resource example
void default_resource_send(const HttpServer &server, shared_ptr<HttpServer::Response> response,
shared_ptr<ifstream> ifs, shared_ptr<vector<char> > buffer);

int main() {
//HTTP-server at port 8080 using 1 thread
//Unless you do more heavy non-threaded processing in the resources,
//1 thread is usually faster than several threads
HttpServer server(8080, 1);

//Add resources using path-regex and method-string, and an anonymous function
//POST-example for the path /string, responds the posted string
server.resource["^/string$"]["POST"]=[](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
//Retrieve string:
auto content=request->content.string();
//request->content.string() is a convenience function for:
//stringstream ss;
//ss << request->content.rdbuf();
//string content=ss.str();

*response << "HTTP/1.1 200 OK\r\nContent-Length: " << content.length() << "\r\n\r\n" << content;
};

//POST-example for the path /json, responds firstName+" "+lastName from the posted json
//Responds with an appropriate error message if the posted json is not valid, or if firstName or lastName is missing
//Example posted json:
//{
// "firstName": "John",
// "lastName": "Smith",
// "age": 25
//}
server.resource["^/json$"]["POST"]=[](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
try {
ptree pt;
read_json(request->content, pt);

string name=pt.get<string>("firstName")+" "+pt.get<string>("lastName");

*response << "HTTP/1.1 200 OK\r\nContent-Length: " << name.length() << "\r\n\r\n" << name;
}
catch(exception& e) {
*response << "HTTP/1.1 400 Bad Request\r\nContent-Length: " << strlen(e.what()) << "\r\n\r\n" << e.what();
}
};

//GET-example for the path /info
//Responds with request-information
server.resource["^/info$"]["GET"]=[](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
stringstream content_stream;
content_stream << "<h1>Request from " << request->remote_endpoint_address << " (" << request->remote_endpoint_port << ")</h1>";
content_stream << request->method << " " << request->path << " HTTP/" << request->http_version << "<br>";
for(auto& header: request->header) {
content_stream << header.first << ": " << header.second << "<br>";
}

//find length of content_stream (length received using content_stream.tellp())
content_stream.seekp(0, ios::end);

*response << "HTTP/1.1 200 OK\r\nContent-Length: " << content_stream.tellp() << "\r\n\r\n" << content_stream.rdbuf();
};

//GET-example for the path /match/[number], responds with the matched string in path (number)
//For instance a request GET /match/123 will receive: 123
server.resource["^/match/([0-9]+)$"]["GET"]=[&server](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
string number=request->path_match[1];
*response << "HTTP/1.1 200 OK\r\nContent-Length: " << number.length() << "\r\n\r\n" << number;
};

//Get example simulating heavy work in a separate thread
server.resource["^/work$"]["GET"]=[&server](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> /*request*/) {
thread work_thread([response] {
this_thread::sleep_for(chrono::seconds(5));
string message="Work done";
*response << "HTTP/1.1 200 OK\r\nContent-Length: " << message.length() << "\r\n\r\n" << message;
});
work_thread.detach();
};

//Default GET-example. If no other matches, this anonymous function will be called.
//Will respond with content in the web/-directory, and its subdirectories.
//Default file: index.html
//Can for instance be used to retrieve an HTML 5 client that uses REST-resources on this server
server.default_resource["GET"]=[&server](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
const auto web_root_path=boost::filesystem::canonical("web");
boost::filesystem::path path=web_root_path;
path/=request->path;
if(boost::filesystem::exists(path)) {
path=boost::filesystem::canonical(path);
//Check if path is within web_root_path
if(distance(web_root_path.begin(), web_root_path.end())<=distance(path.begin(), path.end()) &&
equal(web_root_path.begin(), web_root_path.end(), path.begin())) {
if(boost::filesystem::is_directory(path))
path/="index.html";
if(boost::filesystem::exists(path) && boost::filesystem::is_regular_file(path)) {
auto ifs=make_shared<ifstream>();
ifs->open(path.string(), ifstream::in | ios::binary);

if(*ifs) {
//read and send 128 KB at a time
streamsize buffer_size=131072;
auto buffer=make_shared<vector<char> >(buffer_size);

ifs->seekg(0, ios::end);
auto length=ifs->tellg();

ifs->seekg(0, ios::beg);

*response << "HTTP/1.1 200 OK\r\nContent-Length: " << length << "\r\n\r\n";
default_resource_send(server, response, ifs, buffer);
return;
}
}
}
}
string content="Could not open path "+request->path;
*response << "HTTP/1.1 400 Bad Request\r\nContent-Length: " << content.length() << "\r\n\r\n" << content;
};

thread server_thread([&server](){
//Start server
server.start();
});

//Wait for server to start so that the client can connect
this_thread::sleep_for(chrono::seconds(1));

//Client examples
HttpClient client("localhost:8080");
auto r1=client.request("GET", "/match/123");
cout << r1->content.rdbuf() << endl;

string json_string="{\"firstName\": \"John\",\"lastName\": \"Smith\",\"age\": 25}";
auto r2=client.request("POST", "/string", json_string);
cout << r2->content.rdbuf() << endl;

auto r3=client.request("POST", "/json", json_string);
cout << r3->content.rdbuf() << endl;

server_thread.join();

return 0;
}

void default_resource_send(const HttpServer &server, shared_ptr<HttpServer::Response> response,
shared_ptr<ifstream> ifs, shared_ptr<vector<char> > buffer) {
streamsize read_length;
if((read_length=ifs->read(&(*buffer)[0], buffer->size()).gcount())>0) {
response->write(&(*buffer)[0], read_length);
if(read_length==static_cast<streamsize>(buffer->size())) {
server.send(response, [&server, response, ifs, buffer](const boost::system::error_code &ec) {
if(!ec)
default_resource_send(server, response, ifs, buffer);
else
cerr << "Connection interrupted" << endl;
});
}
}
}

Answer

I've tested as the below steps and it runs flawlessly.

Put this in a html file and run it from a browser:

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<script>
    $.post( "http://localhost:8080/json", 
      JSON.stringify({ firstName: "John", lastName: "Smith", age: 25 }) 
    );
</script>

Change line #53's function of http_examples.cpp to this:

server.resource["^/json$"]["POST"]=[](shared_ptr<HttpServer::Response> response, shared_ptr<HttpServer::Request> request) {
    try {
        ptree pt;
        read_json(request->content, pt);

        string name=pt.get<string>("firstName")+" "+pt.get<string>("lastName");

        *response << "HTTP/1.1 200 OK\r\nContent-Length: " << name.length() << "\r\n" 
                  << "Access-Control-Allow-Origin: *" << "\r\n\r\n" 
                  << name;
    }
    catch(exception& e) {
        *response << "HTTP/1.1 400 Bad Request\r\nContent-Length: " << strlen(e.what()) << "\r\n\r\n" << e.what();
    }
};

Then, recompile like this, and rerun:

Be sure to be in the project folder.

make && ./http_examples