http_client of cpprestsdk/casablanca

Question

I have api https://api.gm-system.net/api/authenticate/searchStaffs/searchText which return a list staff.

And here is my code to access this api using cpprestsdk with c++.

auto fileStream = std::make_shared<ostream>();

    // Open stream to output file.
    pplx::task<void> requestTask = fstream::open_ostream(U("results.html")).then([=](ostream outFile)
    {
        *fileStream = outFile;

        // Create http_client to send the request.
        http_client client(U("https://api.gm-system.net/api/authenticate/searchStaffs/michael"));


        return client.request(methods::GET);
    })

        // Handle response headers arriving.
        .then([=](http_response response)
    {
       ......
    }

This one if fine. But with that i just manually input the "michael" searchText.

How can I make it that it will accept any searchText something like this.

void MyTest(std::string searchText)
{
..... code here

// Create http_client to send the request.
http_client client(U("https://api.gm-system.net/api/authenticate/searchStaffs/" + searchText));

return client.request(methods::GET);

..... code here
}

I already tried this it won't work. Some problem with 'U' macro. From https://github.com/Microsoft/cpprestsdk/wiki/FAQ the discription of U macro is says:

The 'U' macro can be used to create a string literal of the platform type. If you are using a library causing conflicts with the 'U' macro, for example Boost.Iostreams it can be turned off by defining the macro '_TURN_OFF_PLATFORM_STRING' before including the C++ REST SDK header files.

If I point my cursor to U, the error says:

no operator "+" matches these operands operand types are; const wchar_t[57] + const std::string

I hope some can help me. Thanks.

Answer 1

Since

The C++ REST SDK uses a different string type dependent on the platform being targeted. For example for the Windows platforms utility::string_t is std::wstring using UTF-16, on Linux std::string using UTF-8.

you should use the utility::string_t class whenever it is required and don't mix it with std::string or const char * (and use the U macro when in need of a literal).

In other words, your function should accept an utility::string_t as its searchText argument (instead of std::string):

void MyTest(utility::string_t searchText)
{
    http_client client(U("https://api.gm-system.net/api/authenticate/searchStaffs/") + searchText);

    // etc ...

}

use it like this:

int main()
{

    utility::string_t searchText = U("Michael");
    MyTest(searchText);

    return 0;
}

If the function has to be called from a platform specific context, the corresponding std type can be used as the passed in argument type (i.e. use std::wstring on Windows):

std::wstring searchText = L"Michael";
MyTest(searchText);