agron2017 / httpclient

Qt6/C++ library that wraps the QNetworkAccessManager class and simplifies performing HTTP requests in Qt by supporting both synchronous and asynchronous APIs.

httpclient

Introduction

httpclient Qt6/C++ library that wraps the QNetworkAccessManager class and simplifies performing HTTP requests in Qt by supporting both synchronous and asynchronous APIs.

Table of Contents

• Introduction
• Classes
  • NetworkException
  • HttpClient
• Functions
  • writeFile
  • imageFromBytes
• Usage
  • Syncronous APIs
  • Asyncronous APIs
• Linking with CMAKE

Classes

NetworkException

Custom exception thrown when synchronous network calls fail. The caller must catch this exception to avoid segmentation faults.

Public Methods

• NetworkException(int statusCode, const QString &message):
  • Constructs a new NetworkException object.
• int getStatusCode() const:
  • Gets the status code of the response.
• const char *what() const noexcept:
  • Virtual override for the std::exception.

HttpClient

Wrapper class around the QNetworkAccessManager to simplify performing HTTP requests in Qt.

Public Methods

• HttpClient(QObject *parent = nullptr):
  • Constructs a new HttpClient object.
• HttpClient(QObject *parent, const QMap<QString, QString> &headers):
  • Constructs a new HttpClient object with parent and default HTTP headers.
• virtual ~HttpClient():
  • Destroys the HttpClient object.
• static void setRootCA(QString certPath):
  • Sets the Root CA certificate.
• static void setBearerToken(const QString &jwtToken):
  • Sets the Bearer Token for authentication.
• void get(const QString &url) noexcept:
  • Performs a GET request asynchronously.
• void post(const QString &url, const QByteArray &data) noexcept:
  • Performs a POST request asynchronously.
• void put(const QString &url, const QByteArray &data) noexcept:
  • Performs a PUT request asynchronously.
• void patch(const QString &url, const QByteArray &data) noexcept:
  • Performs a PATCH request asynchronously.
• void del(const QString &url) noexcept:
  • Performs a DELETE request asynchronously.
• QByteArray get_sync(const QString &url):
  • Performs a synchronous GET request and blocks until the response arrives.
• QByteArray post_sync(const QString &url, const QByteArray &data):
  • Performs a synchronous POST request and blocks until the response arrives.
• QByteArray put_sync(const QString &url, const QByteArray &data):
  • Performs a synchronous PUT request and blocks until the response arrives.
• QByteArray patch_sync(const QString &url, const QByteArray &data):
  • Performs a synchronous PATCH request and blocks until the response arrives.
• QByteArray del_sync(const QString &url):
  • Performs a synchronous DELETE request and blocks until the response arrives.

Signals

• success(const QByteArray &data):
  • Signal emitted when an asynchronous network call succeeds.
• error(const QString &errorString):
  • Signal emitted when an asynchronous network call fails.

Private Slots

• onReplyFinished():
  • Slot for internal use to process network replies.

Functions

writeFile

Writes data to a file.

Parameters

• const QString &path:
  • The path of the file to write.
• const QByteArray &data:
  • The data to write.

imageFromBytes

Creates a QImage from a byte array.

Parameters

• const QByteArray &data: The byte array containing image data.

Header File

httpclient.h

Usage

Asyncronous APIs

#include <QJsonDocument>
#include <QJsonObject>
#include <QTextStream>
#include <iostream>

#include <httpclient/httpclient.h>

int main(int argc, char* argv[]) {
    QCoreApplication app(argc, argv);

    QMap<QString, QString> headers;
    headers.insert("Content-Type", "application/json");

    // Create an instance of the HttpClient
    HttpClient httpClient(nullptr, headers);

    // Make a GET request
    QString url = "https://api.mysite.com/api/login";

    QJsonObject jsonObject;
    jsonObject.insert("username", "");
    jsonObject.insert("password", "");

    QJsonDocument jsonDoc(jsonObject);
    QByteArray jsonData = jsonDoc.toJson();
    httpClient.post(url, jsonData);

    // Connect signals from the HttpClient
    QObject::connect(&httpClient, &HttpClient::success, [](const QByteArray& data) {
        QTextStream(stdout) << data << "\n";
    });

    QObject::connect(&httpClient, &HttpClient::error, [](const QString& errorString) {
        QTextStream(stderr) << errorString << "\n";
    });

    // Get verified user
    url = "https://api.mysite.com/api/verify-user";
    httpClient.setBearerToken("JWT TOKEN HERE");
    httpClient.get(url);

    HttpClient client2;
    client2.get("https://mysite.com/logo.png");

    QObject::connect(&client2, &HttpClient::success, [](const QByteArray& data) {
        writeFile("logo.png", data);
    });
    return app.exec();
}

Syncronous APIs

#include <QJsonDocument>
#include <QJsonObject>
#include <QTextStream>
#include <iostream>

#include <httpclient/httpclient.h>

int main(int argc, char* argv[]) {
    QCoreApplication app(argc, argv);

    QMap<QString, QString> headers;
    headers.insert("Content-Type", "application/json");

    // Create an instance of the HttpClient
    HttpClient httpClient(nullptr, headers);

    // Make a GET request
    QString url = "https://api.mysite.com/api/login";

    QJsonObject jsonObject;
    jsonObject.insert("username", "");
    jsonObject.insert("password", "");

    QJsonDocument jsonDoc(jsonObject);
    QByteArray jsonData = jsonDoc.toJson();

    QByteArray data;

    try {
        data = httpClient.post_sync(url, jsonData);
        QTextStream(stdout) << data << "\n";
    } catch (const std::exception& e) {
        std::cerr << e.what() << '\n';
    }

    try {
        // Get verified user
        url = "https://api.mysite.com/api/verify-user";
        httpClient.setBearerToken("token here");
        data = httpClient.get_sync(url);
        QTextStream(stdout) << data << "\n";
    } catch (const std::exception& e) {
        std::cerr << e.what() << '\n';
    }

    try {
        HttpClient client2;
        data = client2.get_sync("https://mysite.com/logo.png");
        writeFile("logo-sync.png", data);
    } catch (const std::exception& e) {
        std::cerr << e.what() << '\n';
    }
    return app.exec();
}

Linking with CMAKE

cmake_minimum_required(VERSION 3.2)

project(application LANGUAGES CXX)
include(GNUInstallDirs)

find_package(httpclient REQUIRED)

add_executable(app main.cpp)
target_link_libraries(app PRIVATE httpclient::httpclient)