如何使用可选参数创建构造函数？ [英] How to create constructor with optional parameters?

问题描述

我有__construct（$参数）

pre $ public function __construct（$ nick）{
$ query = SELECT * FROM Users WHERE nick ='。$ nick。';
$ result = App :: runQuery（$ query）;
$ user = $ result-> fetch_object（）;

$ this-> id = $ user-> id;
$ this-> nick = $ user-> nick;
$ this->电子邮件= $ user->电子邮件;
$ this->密码= $ user->密码;
$ this-> birthDay = $ user-> birthDay;
$ this-> sex = $ user-> sex;
$ this-> about = $ user-> about;
$ this-> city = $ user-> city;
$ this-> photo = $ user-> photo;
$ this-> following = $ user-> following;
$ this-> followers = $ user-> followers;
$ this-> statu = $ user-> statu;






$ b现在我想要一个没有参数的默认构造函数这个：



  public function __construct（）{
 
 $ this-> id = NULL; 
 $ this-> nick = NULL; 
 $ this-> email = NULL; 
 $ this-> password = NULL; 
 $ this-> birthDay = NULL; 
 $ this-> sex = NULL; 
 $ this-> about = NULL; 
 $ this-> city = NULL; 
 $ this-> photo = NULL; 
 $ this-> following = NULL; 
 $ this-> followers = NULL; 
 $ this-> statu = NULL; 
 
} 
  

但是有些错误，我得到这样的错误：

 致命错误：无法在/Applications/MAMP/htdocs/xxx/Application/User.php上重新声明User :: __ construct（）第33行
  

如何使用两个带参数且不带参数的构造函数？

解决方案

非常感谢您的回答。

  public function __construct（$ nick）{
 if（$ nick！ = NULL）{//对于用户
 $ query =SELECT * FROM Users WHERE nick ='。$ nick。'; 
 $ result = App :: runQuery（$ query）; 
 $ user = $ result-> fetch_object（）; 
 
 $ this-> id = $ user-> id; 
 $ this-> nick = $ user-> nick; 
 $ this->电子邮件= $ user->电子邮件; 
 $ this->密码= $ user->密码; 
 $ this-> birthDay = $ user-> birthDay; 
 $ this-> sex = $ user-> sex; 
 $ this-> about = $ user-> about; 
 $ this-> city = $ user-> city; 
 $ this-> photo = $ user-> photo; 
 $ this-> following = $ user-> following; 
 $ this-> followers = $ user-> followers; 
 $ this-> statu = $ user-> statu; 
} else {// for null 
 $ this-> id = NULL; 
 $ this-> nick = NULL; 
 $ this-> email = NULL; 
 $ this-> password = NULL; 
 $ this-> birthDay = NULL; 
 $ this-> sex = NULL; 
 $ this-> about = NULL; 
 $ this-> city = NULL; 
 $ this-> photo = NULL; 
 $ this-> following = NULL; 
 $ this-> followers = NULL; 
 $ this-> statu = NULL; 
} 
 
} 
  

有效！

I have __construct($parameter)

public function __construct($nick) {
    $query = "SELECT * FROM Users WHERE nick='".$nick."'";
    $result = App::runQuery($query);
    $user = $result->fetch_object();

    $this->id = $user->id;
    $this->nick = $user->nick;
    $this->email = $user->email;
    $this->password = $user->password;
    $this->birthDay = $user->birthDay;
    $this->sex = $user->sex;
    $this->about = $user->about;
    $this->city = $user->city;
    $this->photo = $user->photo;
    $this->following = $user->following;
    $this->followers = $user->followers;
    $this->statu = $user->statu; 

}

And now I want to have a default constructor without parameters like this:

public function __construct() {

    $this->id = NULL;
    $this->nick = NULL;
    $this->email = NULL;
    $this->password = NULL;
    $this->birthDay = NULL;
    $this->sex = NULL;
    $this->about = NULL;
    $this->city = NULL;
    $this->photo = NULL;
    $this->following = NULL;
    $this->followers = NULL;
    $this->statu = NULL; 

}

But something is wrong and I get error like this:

Fatal error: Cannot redeclare User::__construct() in /Applications/MAMP/htdocs/xxx/Application/User.php on line 33

How can I have two constructors with parameters and without parameters at the same time?

解决方案

Thank you very much for your answer. I have solved the problem with my way.

public function __construct($nick) {
    if($nick != NULL) {//for user 
        $query = "SELECT * FROM Users WHERE nick='".$nick."'";
        $result = App::runQuery($query);
        $user = $result->fetch_object();

        $this->id = $user->id;
        $this->nick = $user->nick;
        $this->email = $user->email;
        $this->password = $user->password;
        $this->birthDay = $user->birthDay;
        $this->sex = $user->sex;
        $this->about = $user->about;
        $this->city = $user->city;
        $this->photo = $user->photo;
        $this->following = $user->following;
        $this->followers = $user->followers;
        $this->statu = $user->statu; 
    }else {//for null
        $this->id = NULL;
        $this->nick = NULL;
        $this->email = NULL;
        $this->password = NULL;
        $this->birthDay = NULL;
        $this->sex = NULL;
        $this->about = NULL;
        $this->city = NULL;
        $this->photo = NULL;
        $this->following = NULL;
        $this->followers = NULL;
        $this->statu = NULL;
    }

}

It works!

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