如何将 PUT 卷曲映射到 CPP 卷曲?

How to map PUT curl into CPP Curlpp?

本文关键字：CPP 卷曲 映射 PUT      更新时间：2023-10-16

我想将下面的 curl(此 curl 在 Linux 终端中正常工作(映射/写入 cpp 代码：

curl -X PUT -u "abc" 
"https://api123.pl" 
-d 'symbol=EB&side=ri&quantity=3'

以下是使用 Curlpp 库的 CPP 代码：

#include <iostream>
#include <sstream>
#include <curlpp/cURLpp.hpp>
#include <curlpp/Easy.hpp>
#include <curlpp/Options.hpp>
using namespace curlpp::options;
using namespace std;
/*
curl -X PUT -u "abc" 
"https://api123.pl" 
-d 'symbol=EB&side=ri&quantity=3'
g++ name1.cpp -lcurl -lcurlpp -o name1 && ./name1
*/
string test(const std::string &url) {
try {
curlpp::Cleanup cleanup;
curlpp::Easy request;
request.setOpt<curlpp::Options::Url>(url);
request.setOpt(new curlpp::options::UserPwd("abc"));
request.setOpt(new curlpp::options::CustomRequest{"PUT"});
//    /*
//does not compile
std::list<std::string> postContent;
postContent.push_back("symbol:EB");
postContent.push_back("side:ri");
postContent.push_back("quantity:3");
request.setOpt(new curlpp::options::PostFields(postContent));
//    */     
std:stringstream content;
content << request;        
return content.str().c_str();
}
catch (const curlpp::RuntimeError &e) {
std::cout << "CURLpp runtime error: " << e.what() << std::endl;
}
catch (const curlpp::LogicError &e) {
std::cout << "CURLpp logic error: " << e.what() << std::endl;
}
throw std::string("Error");
}
int main(int, char **) {
try {
cout << test("https://api123.pl");
}
catch(curlpp::RuntimeError & e) {
std::cout << e.what() << std::endl;
}
catch(curlpp::LogicError & e)   {
std::cout << e.what() << std::endl;
}
return 0;
}

我在编译过程中遇到错误：

1.2putStackoverflow.cpp: In function ‘std::string getJSONAPIResultFromURL(const string&)’:
1.2putStackoverflow.cpp:31:67: error: no matching function for call to ‘curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>::OptionTrait(std::__cxx11::list<std::__cxx11::basic_string<char> >&)’
31 |         request.setOpt(new curlpp::options::PostFields(postContent));
|                                                                   ^
In file included from /usr/include/curlpp/Option.hpp:251,
from /usr/include/curlpp/Easy.hpp:31,
from 1.2putStackoverflow.cpp:4:
/usr/include/curlpp/Option.inl:129:1: note: candidate: ‘curlpp::OptionTrait<OptionType, opt>::OptionTrait() [with OptionType = std::__cxx11::basic_string<char>; CURLoption opt = CURLOPT_POSTFIELDS]’
129 | OptionTrait<OptionType, option>::OptionTrait()
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/curlpp/Option.inl:129:1: note:   candidate expects 0 arguments, 1 provided
/usr/include/curlpp/Option.inl:123:1: note: candidate: ‘curlpp::OptionTrait<OptionType, opt>::OptionTrait(typename curlpp::Option<OptionType>::ParamType) [with OptionType = std::__cxx11::basic_string<char>; CURLoption opt = CURLOPT_POSTFIELDS; typename curlpp::Option<OptionType>::ParamType = const std::__cxx11::basic_string<char>&]’
123 | OptionTrait<OptionType, option>::OptionTrait(typename Option<OptionType>::ParamType value)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/curlpp/Option.inl:123:85: note:   no known conversion for argument 1 from ‘std::__cxx11::list<std::__cxx11::basic_string<char> >’ to ‘curlpp::Option<std::__cxx11::basic_string<char> >::ParamType’ {aka ‘const std::__cxx11::basic_string<char>&’}
123 | OptionTrait<OptionType, option>::OptionTrait(typename Option<OptionType>::ParamType value)
|                                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
In file included from /usr/include/curlpp/Easy.hpp:31,
from 1.2putStackoverflow.cpp:4:
/usr/include/curlpp/Option.hpp:145:8: note: candidate: ‘curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>::OptionTrait(const curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>&)’
145 |  class OptionTrait : public Option<OptionType>
|        ^~~~~~~~~~~
/usr/include/curlpp/Option.hpp:145:8: note:   no known conversion for argument 1 from ‘std::__cxx11::list<std::__cxx11::basic_string<char> >’ to ‘const curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>&’
/usr/include/curlpp/Option.hpp:145:8: note: candidate: ‘curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>::OptionTrait(curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>&&)’
/usr/include/curlpp/Option.hpp:145:8: note:   no known conversion for argument 1 from ‘std::__cxx11::list<std::__cxx11::basic_string<char> >’ to ‘curlpp::OptionTrait<std::__cxx11::basic_string<char>, CURLOPT_POSTFIELDS>&&’

问题出在：

std::list<std::string> postContent;
postContent.push_back("symbol:EB");
postContent.push_back("side:ri");
postContent.push_back("quantity:3");
request.setOpt(new curlpp::options::PostFields(postContent));

编译程序：

g++ name1.cpp -lcurl -lcurlpp -o name1 && ./name1

我不知道如何使用curlpp编写代码将curl映射/写入curl到cpp中。谢谢你的帮助。

PostFields只是cURLpp::OptionTrait<std::string, cURL::CURLOPT_POSTFIELDS>的一个typedef，我在下面简化了事情。

如果您仔细阅读错误消息，它们会告诉您到底出了什么问题：

错误：调用 'curlpp：：OptionTrait<std：：__cxx11：：basic_string>， CURLOPT_POSTFIELDS>：：OptionTrait(std：：__cxx11：：

list<std：：__cxx11：：basic_string>>&('

这基本上是说你不能将std::list<std::string>传递给PostFields的构造函数。 错误详细信息中报告了 4 个候选构造函数，其中没有一个将std::list作为输入：

PostFields()
PostFields(const std::string&)
PostFields(const PostFields&)
PostFields(PostFields&&)

事实上，如果您阅读 cURLpp 文档，则无法从std::list创建PostFields。 根据CURLOPT_POSTFIELDScURL文档，这是有道理的：

将 char * 作为参数传递，指向要在 HTTP POST 操作中发送的完整数据。必须确保数据的格式设置为您希望服务器接收数据的方式。libcurl 不会以任何方式为您转换或编码。例如，Web 服务器可能假定此数据是 url 编码的。

CURLOPT_POSTFIELDS需要单个char*作为输入(cURLpp 使用std::string包装(，因此您必须将PUT数据作为单个 url 编码字符串传递，就像您在命令行上所做的那样，例如：

request.setOpt(new curlpp::Options::PostFields("symbol=EB&side=ri&quantity=3"));

你从哪里得到可以将std::list与PostFields一起使用的想法？

顺便说一句，根据 cURLpp 文档，在向curlpp::Easy对象添加选项时，您实际上不需要使用new：

curlpp::Easy request;
request.setOpt(curlpp::Options::Url(url));
request.setOpt(curlpp::Options::UserPwd("abc"));
request.setOpt(curlpp::Options::CustomRequest("PUT"));
request.setOpt(curlpp::Options::PostFields("symbol=EB&side=ri&quantity=3"));
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