mastodonpp/examples/example09_nlohmann_json.cpp

149 lines
4.6 KiB
C++

/* This file is part of mastodonpp.
* Copyright © 2020 tastytea <tastytea@tastytea.de>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
// Get the last 4 public statuses of an instance and process them with
// nlohmann-json. <https://github.com/nlohmann/json>
#if __has_include("mastodonpp.hpp")
# include "mastodonpp.hpp" // We're building mastodonpp.
#else
# include <mastodonpp/mastodonpp.hpp> // We're building outside mastodonpp.
#endif
// Don't compile if nlohmann-json can't be found.
#if __has_include(<nlohmann/json.hpp>)
# include <nlohmann/json.hpp>
#include <cstdlib>
#include <iostream>
#include <string>
#include <string_view>
#include <vector>
namespace masto = mastodonpp;
using json = nlohmann::json;
using std::exit;
using std::cout;
using std::cerr;
using std::to_string;
using std::string_view;
using std::vector;
void handle_error(const masto::answer_type &answer);
int main(int argc, char *argv[])
{
const vector<string_view> args(argv, argv + argc);
if (args.size() <= 1)
{
cerr << "Usage: " << args[0] << " <instance hostname>\n";
return 1;
}
try
{
// Initialize Instance and Connection.
masto::Instance instance{args[1], {}};
masto::Connection connection{instance};
// Get the last 4 public statuses of the instance.
auto answer{connection.get(masto::API::v1::timelines_public,
{
{"limit", "4"},
{"local", "true"}
})};
if (answer)
{
// Parse JSON string.
auto statuses{json::parse(answer.body)};
for (const auto &status : statuses)
{
// Extract the info we want and print it.
const auto acct{status["account"]["acct"].get<string_view>()};
const auto content{status["content"].get<string_view>()};
const auto id{status["id"].get<string_view>()};
cout << acct << " wrote status " << id << ": \n";
cout << " " << content.substr(0, 76) << "\n";
// Print tags if there are any.
const auto tags{status["tags"]};
if (!tags.empty())
{
cout << " Tags: ";
for (const auto &tag : tags)
{
cout << '#' << tag["name"].get<string_view>() << " ";
}
cout << '\n';
}
// Print the number of attachments.
const auto n_attachments{status["media_attachments"].size()};
if (n_attachments > 0)
{
cout << " " << n_attachments << " attachment";
if (n_attachments > 1)
{
cout << "s";
}
cout << ".\n";
}
}
}
else
{
handle_error(answer);
}
}
catch (const masto::CURLException &e)
{
// Only libcurl errors that are not network errors will be thrown.
// There went probably something wrong with the initialization.
cerr << e.what() << '\n';
}
catch (const nlohmann::detail::exception &e)
{
cerr << "JSON exception: " << e.what() << '\n';
}
}
void handle_error(const masto::answer_type &answer)
{
if (answer.curl_error_code == 0)
{
// If it is no libcurl error, it must be an HTTP error.
cerr << "HTTP status: " << answer.http_status << '\n';
}
else
{
// Network errors like “Couldn't resolve host.”.
cerr << "libcurl error " << to_string(answer.curl_error_code)
<< ": " << answer.error_message << '\n';
}
exit(1);
}
#else
#include <iostream>
int main()
{
std::cout << "Example could not be compiled "
"because nlohmann-json was not found.\n";
}
#endif // __has_include(<nlohmann/json.hpp>)