如何将libpqxx库添加到cmake中？

Question

我正在开发我的C++简单项目。在CMakelists.txt中遇到了一个关键性的问题，我无法正确地链接libpqxx库。

我正在使用：

• C++17
• CMake 3.10
• Ubuntu 16.04
• CLion

这是我的CMakelists.txt文件：

cmake_minimum_required(VERSION 3.10)
project(myserver)

set(CMAKE_CXX_STANDARD 17)

find_package(Boost)
IF (Boost_FOUND)
   include_directories(${Boost_INCLUDE_DIR})
endif()

link_directories(/usr/local/lib)
include_directories(/usr/local/include)

file(GLOB_RECURSE SOURCE_FILES "src/*.cpp")

add_executable(myserver ${SOURCE_FILES})

TARGET_LINK_LIBRARIES(myserver  ${LIBRARIES})

- user name

Answer 1

我找到了解决方案。

cmake_minimum_required(VERSION 3.10)

project(myserver)

set(CMAKE_CXX_STANDARD 17)

find_package(Boost)
if(Boost_FOUND)
    include_directories(${Boost_INCLUDE_DIR})
endif()

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lpqxx -lpq")

set(PQXX /usr/local/include/pqxx)

find_library(PQXX_LIB pqxx)
find_library(PQ_LIB pq)

file(GLOB_RECURSE SOURCE_FILES "src/*.cpp")

add_executable(myserver ${SOURCE_FILES})

TARGET_LINK_LIBRARIES(myserver ${PQXX_LIB} ${PQ_LIB})

- user name

---

在这种情况下使用find包是否更好？我有一个类似的问题，我在另一个问题中发布了它。https://stackoverflow.com/questions/56696047/how-can-i-avoid-linking-directly-to-library-files-in-cmake/56696113#56696113。建议使用一个查找文件。你为什么没有在这里这样做呢？ - Stewart

Answer 2

使用CMake的libpqxx示例，无需在CMake中构建libpqxx

设置环境

1. 安装CMake

cd ~
wget https://github.com/Kitware/CMake/releases/download/v3.14.5/cmake-3.14.5.tar.gz
tar xf cmake-3.14.5.tar.gz
cd cmake-3.14.5
./bootstrap --parallel=10
make -j4
sudo make -j4 install

2. 安装 libpqxx

cd ~
git clone https://github.com/jtv/libpqxx.git
./configure
make -j4
sudo make install

如何构建

mkdir build
cd build
cmake ..
cmake --build .

如何运行

./main

Opened database successfully: postgres

Project

CMakeLists.txt

cmake_minimum_required (VERSION 3.10)
project(example VERSION 1.0.0 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

add_executable(main main.cpp)

target_link_libraries(main -lpqxx -lpq)

main.cpp

#include <iostream>
#include <pqxx/pqxx>

using namespace std;
using namespace pqxx;

int main(int argc, char *argv[])
{
    try
    {
        connection C("dbname = postgres user = postgres password = mysecretpassword \
      hostaddr = 127.0.0.1 port = 5433");
        if (C.is_open())
        {
            cout << "Opened database successfully: " << C.dbname() << endl;
        }
        else
        {
            cout << "Can't open database" << endl;
            return 1;
        }
    }
    catch (const std::exception &e)
    {
        cerr << e.what() << std::endl;
        return 1;
    }
}

使用CMake构建libpqxx示例

环境设置

1. 安装CMake

cd ~
wget https://github.com/Kitware/CMake/releases/download/v3.14.5/cmake-3.14.5.tar.gz
tar xf cmake-3.14.5.tar.gz
cd cmake-3.14.5
./bootstrap --parallel=10
make -j4
sudo make -j4 install

如何构建

mkdir build
cd build
cmake ..
cmake --build .

如何运行

./main

Opened database successfully: postgres

Project

CMakeLists.txt

include(FetchContent)

cmake_minimum_required (VERSION 3.10)
project(example VERSION 1.0.0 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

FetchContent_Declare(
  libpqxx
  GIT_REPOSITORY https://github.com/jtv/libpqxx.git
  GIT_TAG a6b1d60e74c1427c8ac2324b85cd4a0dc2068332
)
set(PQXX_LIBRARIES pqxx_static)

FetchContent_MakeAvailable(libpqxx)

add_executable(main main.cpp)

target_link_libraries(main "${PQXX_LIBRARIES}")

main.cpp

#include <iostream>
#include <pqxx/pqxx>

using namespace std;
using namespace pqxx;

int main(int argc, char *argv[])
{
    try
    {
        connection C("dbname = postgres user = postgres password = mysecretpassword \
      hostaddr = 127.0.0.1 port = 5433");
        if (C.is_open())
        {
            cout << "Opened database successfully: " << C.dbname() << endl;
        }
        else
        {
            cout << "Can't open database" << endl;
            return 1;
        }
    }
    catch (const std::exception &e)
    {
        cerr << e.what() << std::endl;
        return 1;
    }
}

源代码：使用cmake的libpqxx示例

- sun1211