Question

我一直在编写PHP代码已有一段时间了，但最近才说过要掌握OOP方法，并且我试图弄清楚应用程序中某些东西的位置。

我已经编写了以下代码，这是一个数据映射器，用于在我的应用程序中处理来自数据库的团队信息，但我对应该在何处/如何申请感到困惑我的业务逻辑/规则。

例如，如果调用teamMapper类中的delete方法，那么只有当该团队没有参与任何匹配时，才应该继续运行SQL以从数据库中删除该团队。如果不违反任何OOP规则或使课程难以进行单元测试，我将如何进行此操作？

我搜索了这个很多但是到目前为止无济于事，我看到的所有数据映射器都只有删除命令的SQL语句而没有关于是否可以实际执行操作的逻辑或不。

我想我可以通过构造函数方法将一个MatchesMapper实例注入我的TeamMapper类中，然后继续运行像$ this-＆gt; matchesMapper-＆gt; hasMatches（$ team_id）这样的命令，或者使用静态方法一个单独的类做同样的事情，但这样做的正确方法是什么？

非常感谢任何帮助，谢谢。

interface TeamMapperInterface
{
    public function findById($id);
    public function insert(TeamInterface $team);
    public function update(TeamInterface $team);
    public function delete($id);
    public function isTeamByName($name);
}

class TeamMapper implements TeamMapperInterface {

private $db;

public function __construct($db)
{
    // Assign the database connection to a variable which can be used throughout the class
    $this->db = $db;
}

/**
 * Find By Id
 *
 * This function retrieves a team's information from the database and returns it as an object of "team".
 *
 * @param $id
 * @return null|Team
 */
public function findById($id)
{
    // Prepare an SQL statement for attempting to retrieve the team's information from the database
    $sql = 'SELECT `id`, `name`, `country`, `league`, `active` FROM `#` WHERE `id` = ? LIMIT 1';

    // Execute the SQL statement
    $query = $this->db->query($sql, array($id));

    // Check to see whether the database query returned a record or not
    if(is_object($query) === false || $query->num_rows() == 0)
    {
        // Return null as either the database query failed or no record could be found for the given id
        return null;
    }

    // If a team was found then attempt to load it into an a new instance of the team class
    return $this->loadTeam($query->row_array());
}

/**
 * Insert
 *
 * This function takes a team interface object and inserts it into the database.
 *
 * @param TeamInterface $team
 * @return mixed
 * @throws Exception
 */
public function insert(TeamInterface $team)
{
    // Verify that all of the variables in the object passed to this function have been set before attempting to insert the data into the database
    if(is_null($team->getName()) || is_null($team->getCountry()) || is_null($team->getLeague()) || is_null($team->getActive()))
    {
        // Throw an exception because a certain event happened
        throw new Exception('The team\'s information is incomplete and therefore cannot be added to the database.');
    }

    // Check to see if there is already a team in the database with the given name
    if($this->isTeamByName($team->getName()))
    {
        // Throw an exception because a certain event happened
        throw new Exception('The team name specified already exists in the database.');
    }

    // Prepare an SQL statement for inserting the team's information into the database
    $sql = 'INSERT INTO `#` (`id`, `name`, `country`, `league`, `active`) VALUES (?,?,?,?,?)';

    // Execute the SQL statement and then return whether it was successful or not
    return $this->db->query($sql, array('', $team->getName(), $team->getCountry(), $team->getLeague(), $team->getActive()));
}

/**
 * Update
 *
 * This function takes a team interface object and uses it to update the relevant information on the database.
 *
 * @param TeamInterface $team
 * @return mixed
 * @throws Exception
 */
public function update(TeamInterface $team)
{
    // Todo!
}

/**
 * Delete
 *
 * This function delete's a team from the database using the id specified.
 *
 * @param $id
 * @return mixed
 * @throws Exception
 */
public function delete($id)
{
    // Determine if the variable passed to this function was an instance of team interface instead of the expected integer for the id
    if($id instanceof TeamInterface)
    {
        $id = $id->getId();
    }

    // The team can only be deleted if it doesn't have any matches assigned to it
    if(MatchesMapper::numMatchesByTeam($id) > 0)
    {
        // Throw an exception because a certain event happened
        throw new Exception('The team can only be deleted when it doesn\'t have any matches assigned to it.');
    }

    // Prepare an SQL statement for deleting the team's information from the database
    $sql = 'DELETE FROM `#` WHERE `id` = ?';

    // Execute the SQL statement and then return whether it was successful or not
    return $this->db->query($sql, array($id));
}

/**
 * Is Team By Name
 *
 * This function queries the database to determine whether a team exists for a given name
 *
 * @param $name
 * @return bool
 */
public function isTeamByName($name)
{
    // Prepare an SQL statement for checking whether a team already exists in the database
    $sql = 'SELECT `id` FROM `#` WHERE `name` = ? LIMIT 1';

    // Execute the SQL statement
    $query = $this->db->query($sql, array($name));

    // Return the relevant result depending on whether a team was found or not
    return ($query->num_rows() == 1) ? true : false;
}

/**
 * Load Team
 *
 * This function takes an array containing some information about a given team and returns it as an object of "team"
 *
 * @param array $row
 * @return Team
 */
private function loadTeam(array $row)
{
    // Create a new object to hold the information for the team
    $team = new Team($row['name'], $row['country'], $row['league'], $row['active']);

    // Set the team's id as this can't be done through the constructor method of the team class
    $team->setId($row['id']);

    // Return the new team object
    return $team;
}
}

Answer 1

如果存在依赖记录，您可以使用InnoDB外键约束来停止删除。特别是RESTRICT。

请参阅： http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html

数据映射器中的依赖关系/业务逻辑（PHP - OOP）

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