cpp-gui-postgres

A C++ desktop application with a Qt6 GUI that connects to a PostgreSQL database using libpqxx.

Project Structure

cpp-gui-postgres/
├── src/
│   └── main.cpp               # Entry point
├── gui/
│   ├── mainwindow.h
│   └── mainwindow.cpp         # Qt6 main window
├── database/
│   ├── db.h
│   └── db.cpp                 # PostgreSQL connection (libpqxx)
├── models/
│   └── user.h
├── repositories/
│   ├── userrepository.h
│   └── userrepository.cpp
├── services/
│   ├── userservice.h
│   └── userservice.cpp
├── config/
│   ├── env.h
│   └── env.cpp                # .env file loader
├── .env.example               # Environment variable template
├── CMakeLists.txt
└── .vscode/
    ├── c_cpp_properties.json
    └── settings.json

---

Setup

Configure Environment Variables

Copy the example env file and fill in your PostgreSQL credentials:

cp .env.example .env        # Linux / macOS
copy .env.example .env      # Windows (Command Prompt)

Edit .env:

DB_HOST=YOUR_DB_HOST
DB_PORT=YOUR_DB_PORT
DB_USER=YOU_DB_USER
DB_NAME=YOUR_DB_NAME
DB_PASSWORD=YOUR_DB_PASSWORD

---

Platform Setup

Linux

1. Install Required Tools

sudo apt install cmake g++ libpqxx-dev qt6-base-dev

2. Configure VS Code IntelliSense (optional)

Qt headers are typically located at /usr/include/x86_64-linux-gnu/qt6.

Open .vscode/c_cpp_properties.json and ensure includePath includes:

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/**",
                "/usr/include/x86_64-linux-gnu/qt6",
                "/usr/include/x86_64-linux-gnu/qt6/QtWidgets",
                "/usr/include/x86_64-linux-gnu/qt6/QtCore",
                "/usr/include/x86_64-linux-gnu/qt6/QtGui"
            ],
            "defines": [],
            "compilerPath": "/usr/bin/gcc",
            "cStandard": "c17",
            "cppStandard": "gnu++17",
            "intelliSenseMode": "linux-gcc-x64"
        }
    ],
    "version": 4
}

3. Build & Run

mkdir build
cd build
cmake ..
cmake --build .
./app

---

macOS (Homebrew)

1. Install Homebrew (if not already installed)

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

2. Install Required Tools

brew install cmake libpqxx qt

3. Configure VS Code IntelliSense (optional)

Find your Qt prefix path:

brew --prefix qt

Open .vscode/c_cpp_properties.json and update includePath (replace <qt-prefix> with the output above):

{
    "configurations": [
        {
            "name": "Mac",
            "includePath": [
                "${workspaceFolder}/**",
                "<qt-prefix>/include",
                "<qt-prefix>/include/QtWidgets",
                "<qt-prefix>/include/QtCore",
                "<qt-prefix>/include/QtGui"
            ],
            "defines": [],
            "compilerPath": "/usr/bin/clang",
            "cStandard": "c17",
            "cppStandard": "gnu++17",
            "intelliSenseMode": "macos-clang-x64"
        }
    ],
    "version": 4
}

4. Build & Run

mkdir build
cd build
cmake .. -DCMAKE_PREFIX_PATH=$(brew --prefix qt)
cmake --build .
./app

The -DCMAKE_PREFIX_PATH flag tells CMake where to find Qt since Homebrew doesn't install it to a system path.

---

Windows (MSVC / Visual Studio)

1. Install Prerequisites

• Visual Studio 2022 — select the "Desktop development with C++" workload during install
• CMake — check "Add CMake to system PATH" during install
• Qt6 — use the Qt Online Installer, select Qt 6.x.x > MSVC 2019/2022 64-bit
• PostgreSQL — includes headers and libpq needed by libpqxx
• libpqxx — must be built from source (see step 2)

2. Build libpqxx from Source

Open Developer Command Prompt for VS and run:

git clone https://github.com/jtv/libpqxx.git
cd libpqxx
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release -DPostgreSQL_ROOT="C:\Program Files\PostgreSQL\<version>"
cmake --build . --config Release
cmake --install . --prefix "C:\libpqxx"

Replace <version> with your installed PostgreSQL version (e.g., 16).

3. Build the Project

Open Developer Command Prompt for VS from the project root:

mkdir build
cd build
cmake .. ^
  -DCMAKE_PREFIX_PATH="C:\Qt\6.x.x\msvc2022_64" ^
  -Dpqxx_DIR="C:\libpqxx\lib\cmake\libpqxx" ^
  -DPostgreSQL_ROOT="C:\Program Files\PostgreSQL\<version>"
cmake --build . --config Release

Replace C:\Qt\6.x.x\msvc2022_64 with your actual Qt installation path.

4. Run the App

cd Release
app.exe

Make sure .env is placed one directory above the executable (build\.env) so the app can find it at ../.env.

5. Configure VS Code IntelliSense (optional)

Open .vscode/c_cpp_properties.json and update with your actual Qt and libpqxx paths:

{
    "configurations": [
        {
            "name": "Win32",
            "includePath": [
                "${workspaceFolder}/**",
                "C:/Qt/6.x.x/msvc2022_64/include",
                "C:/Qt/6.x.x/msvc2022_64/include/QtWidgets",
                "C:/Qt/6.x.x/msvc2022_64/include/QtCore",
                "C:/Qt/6.x.x/msvc2022_64/include/QtGui",
                "C:/libpqxx/include"
            ],
            "defines": ["_DEBUG", "UNICODE", "_UNICODE"],
            "windowsSdkVersion": "10.0.22621.0",
            "compilerPath": "cl.exe",
            "cStandard": "c17",
            "cppStandard": "c++17",
            "intelliSenseMode": "windows-msvc-x64"
        }
    ],
    "version": 4
}