Question

我正在尝试为一个项目学习Wt，现在我正在尝试学习数据库的一部分。

我一开始就被困住了。我试图从dbo教程（在网站http://www.webtoolkit.eu/wt/doc/tutorial/dbo/tutorial.html#_installing_tt_wt_dbo_tt中有一个教程）中学习它，这是Wt包中的示例（tutorial1.C）

我在ubuntu中使用Qt编译器（5.）。我已经构建了Wt :: Dbo库，正如它在网站教程（上面链接）中所说的那样。问题是它仍然会出现错误;

找不到lGL
collect2：ld返回1退出状态

以下是Wt中的代码（直接从tutorial1.C复制）

/*
 * Copyright (C) 2010 Emweb bvba, Kessel-Lo, Belgium.
 *
 * See the LICENSE file for terms of use.
 */

/*****
 * This file is part of the Wt::Dbo tutorial:
 * http://www.webtoolkit.eu/wt/doc/tutorial/dbo/tutorial.html
 *****/

#include <Wt/Dbo/Dbo>
#include <Wt/Dbo/backend/Sqlite3>
#include <string>

namespace dbo = Wt::Dbo;

/*****
 * Dbo tutorial section 2. Mapping a single class
 *****/

class User {
public:
  enum Role {
    Visitor = 0,
    Admin = 1,
    Alien = 42
  };

  std::string name;
  std::string password;
  Role        role;
  int         karma;

  template<class Action>
  void persist(Action& a)
  {
    dbo::field(a, name,     "name");
    dbo::field(a, password, "password");
    dbo::field(a, role,     "role");
    dbo::field(a, karma,    "karma");
  }
};

void run()
{
  /*****
   * Dbo tutorial section 3. A first session
   *****/

  /*
   * Setup a session, would typically be done once at application startup.
   *
   * For testing, we'll be using Sqlite3's special :memory: database. You
   * can replace this with an actual filename for actual persistence.
   */
  dbo::backend::Sqlite3 sqlite3(":memory:");
  sqlite3.setProperty("show-queries", "true");
  dbo::Session session;
  session.setConnection(sqlite3);

  session.mapClass<User>("user");

  /*
   * Try to create the schema (will fail if already exists).
   */
  session.createTables();

  {
    dbo::Transaction transaction(session);

    User *user = new User();
    user->name = "Joe";
    user->password = "Secret";
    user->role = User::Visitor;
    user->karma = 13;

    dbo::ptr<User> userPtr = session.add(user);
  }

  /*****
   * Dbo tutorial section 4. Querying objects
   *****/

  {
    dbo::Transaction transaction(session);

    dbo::ptr<User> joe = session.find<User>().where("name = ?").bind("Joe");

    std::cerr << "Joe has karma: " << joe->karma << std::endl;

    dbo::ptr<User> joe2 = session.query< dbo::ptr<User> >
      ("select u from user u").where("name = ?").bind("Joe");
  }

  {
    dbo::Transaction transaction(session);

    typedef dbo::collection< dbo::ptr<User> > Users;

    Users users = session.find<User>();

    std::cerr << "We have " << users.size() << " users:" << std::endl;

    for (Users::const_iterator i = users.begin(); i != users.end(); ++i)
      std::cerr << " user " << (*i)->name
        << " with karma of " << (*i)->karma << std::endl;
  }

  /*****
   * Dbo tutorial section 5. Updating objects
   *****/

  {
    dbo::Transaction transaction(session);

    dbo::ptr<User> joe = session.find<User>().where("name = ?").bind("Joe");

    joe.modify()->karma++;
    joe.modify()->password = "public";
  }

  {
    dbo::Transaction transaction(session);
    dbo::ptr<User> joe = session.find<User>().where("name = ?").bind("Joe");
    if (joe)
      joe.remove();
  }

  {
    dbo::Transaction transaction(session);

    dbo::ptr<User> silly = session.add(new User());
    silly.modify()->name = "Silly";
    silly.remove();
  }

}

int main(int argc, char **argv)
{
  run();
}

提前致谢

Answer 1

由于.pro文件，似乎出现问题。我不知道它是如何工作的但是当我第一次实现它时替换了pro文件时问题就消失了（从另一个.pro文件复制粘贴，只需要很少的修改，最后一个也不应该有任何差别。一）。

Answer 2

首先，您需要了解Qt不是编译器。它是跨平台应用程序和GUI开发的框架。我相信，你可能也在使用Qt Creator这是一个IDE。实际的编译器可能是gcc，clang，msvc或其他一些。链接错误表明您将其构建为gui应用程序。添加＆＃39; CONFIG - = qt＆＃39;在您的专业文件中将解决问题。或者，在创建新项目时，选择Non-Qt Project-＆gt; Plain C ++ Application。

Wt数据库Wt :: Dbo

2 个答案: