I try to get all available collections from a MongoDB using POCO C++ driver. But I haven't found anything on web and tried using the createCommand() with selector("$query").add("listCollections", 1) without any success. It seems POCO does not have an implementation for querying all collections inside a db or does anybody know how to do this?
MongoDB driver itself has a command like getCollectionNames() but I can not find this inside POCO.
I tried using this snippet:
Poco::MongoDB::Database db("db_name");
auto command = db.createCommand();
command->selector().addNewDocument("$query").add("listCollections", 1);
Poco::MongoDB::ResponseMessage resp;
DBCONN.sendRequest(*command, resp);
I get a document back with:
Content: {"ok":0,"errmsg":"no such cmd: listCollections","bad cmd":{"$query":{"listCollections":1}}}
Related
I have a small C++ project and need to access a mySQL DB from it, so i have setup mySQL Connector for C++.
This is done on OS X 10.10, and i got no problems with the compilation/linking.
I have written a class for all the mysql stuff, and in the constructor i want to setup the connection to the db. However, this seems to be kinda hard.
Here is the relevant part from the class:
class mysql{
public:
mysql(std::string server, std::string user, std::string password);
private:
sql::mysql::MySQL_Driver *driver;
sql::Connection *con;
std::string last_error = "";
};
And here the implementation:
mysql::mysql(std::string server, std::string user, std::string password){
driver = sql::mysql::get_mysql_driver_instance();
try{
con = driver->connect(server, user, password);
last_error = "";
}
catch(sql::SQLException &e){
last_error = e.what();
}
}
However, when i create an object of that class like this:
mysql db("tcp://127.0.0.1:3306", "root", "secretsecret");
I then have this in my last_error string:
Unknown MySQL server host '???' (0)
The "host" sometimes differs even tho i dont change it in code. This seems like internally a different memory location is read out as it should be.
But even if i pass the connect() variables directly when i call it, i get this error. Same when saving those three variables internally in the mysql class and use those to call connect().
Anyone has an idea what could cause this? I have a similar implementation in a different project where this does work fine so im kinda confused :/
Here is a post that matches to your circumstances (The C++ connector works on linux and fails on OSX).
With using mysql logging/tracing or running it in debugger, you may be able to gather more information to report to mysql developers. You may have better luck.
After a long time of googeling i found this the most useful link: https://apple.stackexchange.com/questions/251290/weird-behaviour-of-mysql-connector-c-in-osx
Following the hints there, i recompiled the myscl c connector and then the mysql c++ connector (version 1.1.6 cause 1.1.7 caused a json error while compiling).
I also saw in the cmake logs of the c++ connector that Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ was used to compile the library.
So i used that one too for my compilation. It could be that this would work, tho im also including wxwisgeds in my project resulting in this error:
/usr/local/include/wx-3.0/wx/strvararg.h:30:18: fatal error: 'tr1/type_traits' file not found
#include <tr1/type_traits>
I found some hints for that one but they all just produced a massiv amount of new errors, so i stopped digging deeper here.
My best options would be to create two seperate programs, on to communicate with mysql and one to provide the gui and let them both communicate with each other either via sockets or files providing a very inefficient access to a mysql db.
Good luck to anyone who runs into the same thing..
I want my servlet to establish a connection with solr so as to perform query. using eclipse I have created a simple JSP file for the user to input their query, then it will call the doGet() method from the servlet. From the servlet i try to use solrj to connect with solr
my solrj code is as below.
HttpSolrServer solr = new HttpSolrServer("http://localhost:8983/solr");
SolrQuery query = new SolrQuery();
query.setQuery("sony digital camera");
query.addFilterQuery("cat:electronics","store:amazon.com");
query.setFields("id","price","merchant","cat","store");
query.setStart(0);
query.set("defType", "edismax");
QueryResponse response = solr.query(query);
SolrDocumentList results = response.getResults();
for (int i = 0; i < results.size(); ++i) {
System.out.println(results.get(i));
}
}
Its basically just simple code available online, there is no syntax error which means that the program detects the library files. However on run time the program returns classNotFoundException error.
This prompt me thinking whether i can implement solrj on servlet. Anyone can advise me where i can exactly use the solrj code? I think that the code is right but just that i implement solrj wrongly.
Thanks in advance!
The exception is saying that your runtime classpath is wrong.
Assuming you're running this class in a servlet container, most probably what you're missing is not a Java EE jar but instead has something to do with SolrJ.
Solrj has few dependencies: you can find them in the Solr distribution or if you have confidence with Apache Maven, you can use it for individuating those jars.
In any case, once you identified those libraries, you have to put them under WEB-INF/lib of your webapp
For a list of dependencies you can read here: http://mvnrepository.com/artifact/org.apache.solr/solr-solrj/4.10.3
I need to create a simple web service (being the "server"). The goal is to provide some data I do read in an Qt / C++ application as JSON data. Basically a JavaScript application in the browser shall read its data from the Qt app. It is usually a single user scenario, so the user runs a Google Maps application in her browser, while additional data come from the Qt application.
So far I have found these libs:
Qxt: http://libqxt.bitbucket.org/doc/0.6/index.html but being a newbie on C++/Qt I miss some examples. Added: I have found one example here
gSoap: http://www.cs.fsu.edu/~engelen/soap.html has more examples and documentation and also seems to support JSON
KD SOAP: http://www.kdab.com/kdab-products/kd-soap/ with no example as far as I can tell, docu is here
Qt features itself, but it is more about acting as a client: http://qt-project.org/videos/watch/qt-networking-web-services
Checking SO gives me basically links to the above libs
webservice with Qt with an example I do not really get.
How to Create a webservice by Qt
So basically I do have the following questions:
Which lib would you use? I want to keep it as simple as possible and would need an example.
Is there another (easy!) way to provide the JSON data to the JavaScript Web page besides the WebService?
-- Edit, remarks: ---
Needs to be application intrinsic. No web server can be installed, no extra run time can be used. The user just runs the app. Maybe the Qt WebKit could be an approach....
-- Edit 2 --
Currently checking the tiny web servers as of SO " Qt HTTP Server? "
As of my tests, currently I am using QtWebApp: http://stefanfrings.de/qtwebapp/index-en.html This is one of the answers of Edit 2 ( Qt HTTP Server? )
Stefan's small WebServer has some well documented code, is written in "Qt C++" and easy to use, especially if you have worked with servlets already. Since it can be easily integrated in my Qt project, I'll end up with an internal WebServer.
Some demo code from my JSON tests, showing that generating the JSON content is basically creating a QString.
void WebServiceController::service(HttpRequest& request, HttpResponse& response) {
// set some headers
response.setHeader("Content-Type", "application/json; charset=ISO-8859-1");
response.setCookie(HttpCookie("wsTest","CreateDummyPerson",600));
QString dp = WebServiceController::getDummyPerson();
QByteArray ba = dp.toLocal8Bit();
const char *baChar = ba.data();
response.write(ba);
}
If someone has easy examples with other libs to share, please let me know.
QByteArray ba = dp.toLocal8Bit();
const char *baChar = ba.data();
You don't need to convert the QByteArray to char array. Response.write() can also be called with a QByteArray.
By the way: qPrintable(dp) is a shortcut to convert from QString to char array.
I am trying to do a JSON Restful web service in C/C++.
I have tried Axis2/C and Staff, which work great for XML serialization/deserialization but not for JSON.
You might want to take a look at Casablanca introduced in Herb Sutter's blog.
there are a small number of libraries that support creating rest services with c, e.g. restinio:
#include <restinio/all.hpp>
int main()
{
restinio::run(
restinio::on_this_thread()
.port(8080)
.address("localhost")
.request_handler([](auto req) {
return req->create_response().set_body("Hello, World!").done();
}));
return 0;
}
try https://github.com/babelouest/ulfius great library to build C/C++ Restful APIs. can support all platforms: Linux, FreeBSD, Windows and others
Try ngrest. It's a simple but fast C++ RESTful JSON Web Services framework. It can be deployed on top of Apache2, Nginx or own simple http server.
Regarding Axis2/C with JSON. It's seems that official Axis2/C no longer maintained. So Axis2/C become obsolete (but still works).
JSON support for Axis2/C is available in axis2c-unofficial project.
There are an installation manuals on how to install Axis2/C with JSON support under Linux, Windows using binary package, Windows from source code.
You can try it with WSF Staff using Customers (REST) example in JSON mode (which is available from staff/samples/rest/webclient directory of staff source code).
You could look at ffead-cpp. Apart from providing support for json and restfull web services it also includes more features. This framework may be too heavy weight for your situation though.
For C++ web service, I am using the following stack:
ipkn/crow C++ micro web framework
nlohmann/json for json serialization/deserialization.
Take a look at Oat++
It has:
URL routing with URL-parameters mapping
Support for Swagger-UI endpoint annotations.
Object-Mapping with JSON support.
Example endpoint:
ENDPOINT("GET", "users/{name}", getUserByName, PATH(String, name)) {
auto userDto = UserDto::createShared();
userDto->name = name;
return createDtoResponse(Status::CODE_200, userDto);
}
Curl:
$ curl http://localhost:8000/users/john
{"name":"john"}
You may want to take a look at webcc.
It's a lightweight C++ HTTP client and server library for embedding purpose based on Boost.Asio (1.66+).
It's quite promising and actively being developed.
It includes a lot of examples to demonstrate how to create a server and client.
There is a JIRA project resolved the support of JSON in AXIS2/C .
I implemented in my project and I managed with the writer (Badgerfish convention) but still I am trying to manage with the reader.It seems more complicated managing with the stack in the memory.
JSON and JSONPath are supported for both C and C++ in gsoap with a new code generator and a new JSON API to get you started quickly.
Several JSON, JSON-RPC and REST examples are included. Memory management is automatic.
The code generator can be useful. Take for example the json.org menu.json snippet:
{ "menu": {
"id": "file",
"value": "File",
"popup": {
"menuitem": [
{"value": "New", "onclick": "CreateNewDoc()"},
{"value": "Open", "onclick": "OpenDoc()"},
{"value": "Close", "onclick": "CloseDoc()"}
]
}
}
}
The gsoap command jsoncpp -M menu.json generates this code to populate a JSON value:
value x(ctx);
x["menu"]["id"] = "file";
x["menu"]["value"] = "File";
x["menu"]["popup"]["menuitem"][0]["value"] = "New";
x["menu"]["popup"]["menuitem"][0]["onclick"] = "CreateNewDoc()";
x["menu"]["popup"]["menuitem"][1]["value"] = "Open";
x["menu"]["popup"]["menuitem"][1]["onclick"] = "OpenDoc()";
x["menu"]["popup"]["menuitem"][2]["value"] = "Close";
x["menu"]["popup"]["menuitem"][2]["onclick"] = "CloseDoc()";
Also reading parsed JSON values and JSONPath code can be generated by this tool.
EDIT
To clarify, the jsoncpp command-line code generator shows the API code to read and write JSON data by using a .json file as a template, which I found is useful to save time to write the API code to populate and extract JSON data. JSONPath query code can also be generated with this tool.
For web service in C, you can leverage library like ulfius, civetweb:
https://github.com/babelouest/ulfius
https://github.com/civetweb/civetweb/blob/master/docs/Embedding.md
For web service in C++, you can leverage library like libhv, restbed:
https://github.com/ithewei/libhv
https://github.com/Corvusoft/restbed
I'm trying to use the libcurl in a C/C++ application to post files to DropBox.
I would like to use the "/files (POST)" API as documented here...
https://www.dropbox.com/developers/reference/api#files-POST
I am having problems with properly authenticating (OAuth) this call. It is unclear to me how to properly create the authentication signature.
From some a sample I saw, it looked like they were reading in the whole file to create the HMAC-SHA1 encoding on. This seems problematic on large files.
Does anyone have experience or insight using this API or something similar?
I have just use the libouth and libcurl to get information from sina weibo. here is my example for you refer. you can also refer the liboauth test programmer in the tests dir, oauthtest.c
if (use_post)
{
req_url = oauth_sign_url2(test_call_uri, &postarg, OA_HMAC, NULL, c_key, c_secret, t_key, t_secret);
reply = oauth_http_post(req_url,postarg);
}
I suggest using BOOST ASIO . Makes uploading and downloading a breeze.