Re: [Cppcms-users] Compile error: traits is not a template

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I don't remember exact API from the head, try - there are plenty ways to do stuff 

http://cppcms.com/wikipp/en/page/cppcms_1x_json

For example, this works..

        std::vector<booster::shared_ptr<int> > vals;
        vals.push_back(booster::shared_ptr<int>( new int(1)));
        vals.push_back(booster::shared_ptr<int>( new int(2)));

        cppcms::json::value v;
        v["x"]=cppcms::json::array();
        cppcms::json::array &a = v["x"].array();

        a.resize(vals.size());

        for(size_t i = 0;i<vals.size();i++)
                a[i] = *vals[i];

        std::cout << v << std::endl;

Also if you don't want to do copy... use cppcms::json::value::swap

That not that hard :-)

Artyom Beilis
--------------
CppCMS - C++ Web Framework:   http://cppcms.com/
CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/

>________________________________
> From: 陈抒 <csf...@gm...>
>To: Artyom Beilis <art...@ya...>; cpp...@li... 
>Sent: Saturday, September 1, 2012 4:26 PM
>Subject: Re: [Cppcms-users] Compile error: traits is not a template
> 
>
>Also, when I said deep copy, I mean the following codes:
>
>
>for(size_t i = 0;i<in.values_.size();i++)
>  a[i]=*in.values_[i];
>
>
>
>陈抒 
>Best regards
>http://blog.csdn.net/sheismylife
>
>
>
>On Sat, Sep 1, 2012 at 9:24 PM, 陈抒 <csf...@gm...> wrote:
>
>I tried you codes the first time. It can't be compiled.
>>
>>
>>$ make
>>Scanning dependencies of target cppweb
>>[  3%] Building CXX object bin/CMakeFiles/cppweb.dir/groups.cpp.o
>>In file included from /home/chenshu/work/kaimei/cppweb/src/groups.cpp:1:0:
>>/home/chenshu/work/kaimei/cppweb/include/groups.h: In static member function ‘static void cppcms::json::traits<kaimei::groups>::set(cppcms::json::value&, const kaimei::groups&)’:
>>/home/chenshu/work/kaimei/cppweb/include/groups.h:39:60: error: invalid initialization of non-const reference of type ‘cppcms::json::array& {aka std::vector<cppcms::json::value>&}’ from an rvalue of type ‘void’
>>make[2]: *** [bin/CMakeFiles/cppweb.dir/groups.cpp.o] Error 1
>>make[1]: *** [bin/CMakeFiles/cppweb.dir/all] Error 2
>>make: *** [all] Error 2
>>
>>
>>line 39 is :
>>cppcms::json::array &a=v.at("values",cppcms::json::array());
>>
>>
>>I upgraded CppCMS to latest version, also read your API document.
>>It seems your 'at' member function return 'void'
>>
>>陈抒 
>>Best regards
>>http://blog.csdn.net/sheismylife
>>
>>
>>
>>On Sat, Sep 1, 2012 at 9:15 PM, Artyom Beilis <art...@ya...> wrote:
>>
>>You hadn't read my code correctly
>>>
>>>
>>>cppcms::json::array &a=v.at("values",cppcms::json::array());
>>>
>>>
>>>a is a reference and you fill it.
>>>
>>>
>>>Anyway read the cppcms::json::value reference documentation for further details
>>>
>>> 
>>>Artyom Beilis
>>>--------------
>>>CppCMS - C++ Web Framework:   http://cppcms.com/
>>>CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/
>>>
>>>
>>>
>>>>________________________________
>>>> From: 陈抒 <csf...@gm...>
>>>>To: Artyom Beilis <art...@ya...>; cpp...@li... 
>>>>Sent: Saturday, September 1, 2012 3:32 PM
>>>>
>>>>Subject: Re: [Cppcms-users] Compile error: traits is not a template
>>>> 
>>>>
>>>>
>>>>I changed your codes a bit. 
>>>>namespace cppcms {
>>>>  namespace json {
>>>>
>>>>
>>>>    template<>
>>>>      struct traits<kaimei::groups> {
>>>>
>>>>
>>>>      static void set(value &v, kaimei::groups const& in) {
>>>>v.set("size", in.size());
>>>>cppcms::json::array a;
>>>>a.resize(in.values_.size());
>>>>for(size_t i = 0; i < in.values_.size(); i++) {
>>>>  a[i]=*in.values_[i];
>>>>}
>>>>v.set("values", a);
>>>>      }
>>>>    };
>>>>
>>>>
>>>>  }
>>>>}
>>>>
>>>>
>>>>Two issues:
>>>>1. This way is not efficient, a lot of deep copy would occur when copying vector from array.
>>>>My original way is very simple, create a stringstream object, groups object converts all member variables into string, append them to stringstream. It does not looks elegant, but faster. 
>>>>2. It doesn't work. I got an exception:
>>>>cppcms::json::bad_cast:  error converting from object
>>>>
>>>>
>>>>陈抒 
>>>>Best regards
>>>>http://blog.csdn.net/sheismylife
>>>>
>>>>
>>>>
>>>>On Sat, Sep 1, 2012 at 5:41 PM, Artyom Beilis <art...@ya...> wrote:
>>>>
>>>>Because shared_ptr<group> is not specialized for traits...
>>>>>
>>>>>You need manually create an array and sets its memebers.i.e
>>>>>
>>>>>Something like that:
>>>>>
>>>>>cppcms::json::array &a=v.at("values",cppcms::json::array());
>>>>>a.resize(in.values_.size());
>>>>>for(size_t i = 0;i<in.values_.size();i++)
>>>>>  a[i]=*in.values_[i];
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>Artyom Beilis
>>>>>--------------
>>>>>CppCMS - C++ Web Framework:   http://cppcms.com/
>>>>>CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/
>>>>>
>>>>>
>>>>>
>>>>>>________________________________
>>>>>> From: 陈抒 <csf...@gm...>
>>>>>>To: Artyom Beilis <art...@ya...>; cpp...@li...
>>>>>>Sent: Saturday, September 1, 2012 10:05 AM
>>>>>>Subject: Re: [Cppcms-users] Compile error: traits is not a template
>>>>>
>>>>>>
>>>>>>
>>>>>>Thank you. But I see new error.
>>>>>>groups.h file:
>>>>>>
>>>>>>
>>>>>>#ifndef __GROUPS_H
>>>>>>#define __GROUPS_H
>>>>>>
>>>>>>
>>>>>>#include <vector>
>>>>>>#include <boost/shared_ptr.hpp>
>>>>>>#include "group.h"
>>>>>>
>>>>>>
>>>>>>namespace kaimei{
>>>>>>
>>>>>>
>>>>>>  class groups{
>>>>>>  public:
>>>>>>    typedef std::vector<boost::shared_ptr<group> >::iterator iterator;
>>>>>>    typedef std::vector<boost::shared_ptr<group> >::const_iterator const_iterator;
>>>>>>
>>>>>>
>>>>>>    void add(boost::shared_ptr<group> g);
>>>>>>
>>>>>>
>>>>>>    bool empty() const;
>>>>>>
>>>>>>
>>>>>>    unsigned int size() const;
>>>>>>
>>>>>>
>>>>>>    std::string json_string() const;
>>>>>>    
>>>>>>    friend class cppcms::json::traits<kaimei::groups>;
>>>>>>
>>>>>>
>>>>>>  private:
>>>>>>    std::vector<boost::shared_ptr<kaimei::group> > values_;
>>>>>>  };
>>>>>>
>>>>>>
>>>>>>}
>>>>>>
>>>>>>
>>>>>>namespace cppcms {
>>>>>>  namespace json {
>>>>>>
>>>>>>
>>>>>>    template<>
>>>>>>      struct traits<kaimei::groups> {
>>>>>>
>>>>>>
>>>>>>      static void set(value &v, kaimei::groups const& in) {
>>>>>>v.set("size", in.size());
>>>>>>v.set("values", in.values_);
>>>>>>      }
>>>>>>    };
>>>>>>
>>>>>>
>>>>>>  }
>>>>>>}
>>>>>>
>>>>>>
>>>>>>#endif
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>error message:
>>>>>>  3%] Generating ../../src/view/welcome.cpp, ../../src/view/home.cpp, ../../src/view/gprs_message.cpp, ../../src/view/gprs_manager.cpp, ../../src/view/gprs_password.cpp, ../../src/view/gprs_log.cpp, ../../src/view/register_client.cpp, ../../src/view/gprsConfig.cpp, ../../src/view/login.cpp, ../../src/view/group_management.cpp
>>>>>>[  6%] Building CXX object bin/CMakeFiles/cppweb.dir/groups.cpp.o
>>>>>>In file included from /home/chenshu/work/kaimei/cppweb/include/group.h:5:0,
>>>>>>                 from /home/chenshu/work/kaimei/cppweb/include/groups.h:6,
>>>>>>                 from /home/chenshu/work/kaimei/cppweb/src/groups.cpp:1:
>>>>>>/usr/include/cppcms/json.h: In member function ‘void cppcms::json::value::set_value(const T&) [with T = boost::shared_ptr<kaimei::group>]’:
>>>>>>/usr/include/cppcms/json.h:604:5:   instantiated from ‘static void cppcms::json::traits<std::vector<T> >::set(cppcms::json::value&, const std::vector<T>&) [with T = boost::shared_ptr<kaimei::group>]’
>>>>>>/usr/include/cppcms/json.h:247:4:   instantiated from ‘void cppcms::json::value::set_value(const T&) [with T = std::vector<boost::shared_ptr<kaimei::group> >]’
>>>>>>/usr/include/cppcms/json.h:316:4:   instantiated from ‘cppcms::json::value::value(const T&) [with T = std::vector<boost::shared_ptr<kaimei::group> >]’
>>>>>>/usr/include/cppcms/json.h:352:4:   instantiated from ‘void cppcms::json::value::set(const char*, const T&) [with T = std::vector<boost::shared_ptr<kaimei::group> >]’
>>>>>>/home/chenshu/work/kaimei/cppweb/include/groups.h:39:28:   instantiated from here
>>>>>>/usr/include/cppcms/json.h:247:4: error: incomplete type ‘cppcms::json::traits<boost::shared_ptr<kaimei::group> >’ used in nested name specifier
>>>>>>make[2]: *** [bin/CMakeFiles/cppweb.dir/groups.cpp.o] Error 1
>>>>>>make[1]: *** [bin/CMakeFiles/cppweb.dir/all] Error 2
>>>>>>make: *** [all] Error 2
>>>>>>
>>>>>>
>>>>>>陈抒
>>>>>>Best regards
>>>>>>http://blog.csdn.net/sheismylife
>>>>>>
>>>>>>
>>>>>>
>>>>>>On Sat, Sep 1, 2012 at 2:34 PM, Artyom Beilis <art...@ya...> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>But I got error when compiling another class. It has group.h and group.cpp file.
>>>>>>>>
>>>>>>>>
>>>>>>>>#ifndef __GROUP_H
>>>>>>>>#define __GROUP_H
>>>>>>>>
>>>>>>>>
>>>>>>>>#include <string>
>>>>>>>>
>>>>>>>>
>>>>>>>>namespace kaimei{
>>>>>>>>...
>>>>>>>
>>>>>>>}
>>>>>>>>
>>>>>>>>
>>>>>>>>namespace cppcms {
>>>>>>>>  namespace json {
>>>>>>>>    template<>
>>>>>>>>      struct traits<kaimei::group> {
>>>>>>>>...
>>>>>>>>      }
>>>>>>>>  }
>>>>>>>>}
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> [snip]
>>>>>>>
>>>>>>>>
>>>>>>>>I am not good at template programming. Why did this happen?
>>>>>>>>
>>>>>>>
>>>>>>>You can't specialize undefined struct - you need to include <cppcms/json.h>
>>>>>>>header. It provides the original traits struct and than you specialize it for
>>>>>>>your type of class
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>陈抒
>>>>>>>>Best regards
>>>>>>>>http://blog.csdn.net/sheismylife
>>>>>>>>
>>>>>>>
>>>>>>>Regards,
>>>>>>>Artyom
>>>>>>>
>>>>>>>
>>>>>>>------------------------------------------------------------------------------
>>>>>>>Live Security Virtual Conference
>>>>>>>Exclusive live event will cover all the ways today's security and
>>>>>>>threat landscape has changed and how IT managers can respond. Discussions
>>>>>>>will include endpoint security, mobile security and the latest in malware
>>>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>>>_______________________________________________
>>>>>>>Cppcms-users mailing list
>>>>>>>Cpp...@li...
>>>>>>>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>>>>>>>
>>>>>>
>>>>>>------------------------------------------------------------------------------
>>>>>>Live Security Virtual Conference
>>>>>>Exclusive live event will cover all the ways today's security and
>>>>>>threat landscape has changed and how IT managers can respond. Discussions
>>>>>>will include endpoint security, mobile security and the latest in malware
>>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>>_______________________________________________
>>>>>>Cppcms-users mailing list
>>>>>>Cpp...@li...
>>>>>>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>>>>>>
>>>>>>
>>>>>> 
>>>>>
>>>>>------------------------------------------------------------------------------
>>>>>Live Security Virtual Conference
>>>>>Exclusive live event will cover all the ways today's security and
>>>>>threat landscape has changed and how IT managers can respond. Discussions
>>>>>will include endpoint security, mobile security and the latest in malware
>>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>>_______________________________________________
>>>>>Cppcms-users mailing list
>>>>>Cpp...@li...
>>>>>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>>>>>
>>>>
>>>>------------------------------------------------------------------------------
>>>>Live Security Virtual Conference
>>>>Exclusive live event will cover all the ways today's security and 
>>>>threat landscape has changed and how IT managers can respond. Discussions 
>>>>will include endpoint security, mobile security and the latest in malware 
>>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>>_______________________________________________
>>>>Cppcms-users mailing list
>>>>Cpp...@li...
>>>>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>>>>
>>>>
>>>>
>>>------------------------------------------------------------------------------
>>>Live Security Virtual Conference
>>>Exclusive live event will cover all the ways today's security and
>>>threat landscape has changed and how IT managers can respond. Discussions
>>>will include endpoint security, mobile security and the latest in malware
>>>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>>>_______________________________________________
>>>Cppcms-users mailing list
>>>Cpp...@li...
>>>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>>>
>>>
>>
>
>------------------------------------------------------------------------------
>Live Security Virtual Conference
>Exclusive live event will cover all the ways today's security and 
>threat landscape has changed and how IT managers can respond. Discussions 
>will include endpoint security, mobile security and the latest in malware 
>threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
>_______________________________________________
>Cppcms-users mailing list
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>https://lists.sourceforge.net/lists/listinfo/cppcms-users
>
>
> 