Fatal error: Uncaught Error: Call to a member function prepare()

Question

我想在用户中添加信息session。我从数据库中获取这些数据，但我总是遇到这个错误：

Fatal error: Uncaught Error: Call to a member function prepare() on null in /web/htdocs/-----/home/classes/functions.php:10 Stack trace: #0 /web/htdocs/------/home/classes/functions.php(25): Functions->getInformazioni(11) #1 /web/htdocs/------/home/profile.php(11): Functions->dropInformazioni(11) #2 {main} thrown in /web/htdocs/---------/home/classes/functions.php on line 10

我用“-----”替换我的网站。

这是我的代码： profile.php

<?php
require(__DIR__.'/includes/config.php');
$title = 'F&S: Profilo';
require(__DIR__.'/layout/head.php');

//if not logged in redirect to login page
if (! $user->is_logged_in()){
    header('Location: index.php');
    exit();
}
$function->dropInformazioni($_SESSION['memberID']);
//include header template
require(__DIR__.'/layout/header.php');
?>
<div class="container">
    <div class="main-body">
          <div class="row gutters-sm">
            <div class="col-md-4 mb-3">
              <div class="card">
                <div class="card-body">
                  <div class="d-flex flex-column align-items-center text-center">
                    <img class="img-res" src="https://avatar.tobi.sh/<?php echo $_SESSION['email'];?>.svg?text=<?php echo (substr($_SESSION['name'], 0, 1)); echo (substr($_SESSION['surname'], 0, 1));?>" width="150">
                    <div class="mt-3">
                      <h4><?php echo $_SESSION['name']; ?> <?php echo $_SESSION['surname']; ?></h4>
                    </div>
                  </div>
                </div>
              </div>
            </div>
            <div class="col-md-8">
              <div class="card mb-3">
                <div class="card-body">
                  <div class="row">
                    <div class="col-sm-3">
                      <h6 class="mb-0">Full Name</h6>
                    </div>
                    <div class="col-sm-9 text-secondary">
                      Kenneth Valdez
                    </div>
                  </div>
                  <hr>
                  <div class="row">
                    <div class="col-sm-3">
                      <h6 class="mb-0">Email</h6>
                    </div>
                    <div class="col-sm-9 text-secondary">
                      fip@jukmuh.al
                    </div>
                  </div>
                  <hr>
                  <div class="row">
                    <div class="col-sm-3">
                      <h6 class="mb-0">Phone</h6>
                    </div>
                    <div class="col-sm-9 text-secondary">
                      (239) 816-9029
                    </div>
                  </div>
                  <hr>
                  <div class="row">
                    <div class="col-sm-3">
                      <h6 class="mb-0">Mobile</h6>
                    </div>
                    <div class="col-sm-9 text-secondary">
                      (320) 380-4539
                    </div>
                  </div>
                  <hr>
                  <div class="row">
                    <div class="col-sm-3">
                      <h6 class="mb-0">Address</h6>
                    </div>
                    <div class="col-sm-9 text-secondary">
                      Bay Area, San Francisco, CA
                    </div>
                  </div>
                  <hr>
                  <div class="row">
                    <div class="col-sm-12">
                      <a class="btn btn-info " href="#">Edit</a>
                    </div>
                  </div>
                </div>
              </div>
                </div>
              </div>



            </div>
          </div>
<?php
require(__DIR__.'/layout/footer.php');
?>

functions.php的一部分

private function getInformazioni($id) {
      try {
        $stmt = $this->$_db->prepare('SELECT memberID, name, surname, comune, provincia, via, prefisso_int, telefono FROM members WHERE memberID = '.$id.' AND active="Yes"');
        $stmt->execute(array('memberID' => $id));
        return $stmt->fetch();
      } catch (PDOException $e) {
        echo "$e";
      }


    }

    public function dropInformazioni($id) {
      $row = $this->getInformazioni($id);
      $_SESSION['name'] = $row['name'];
      $_SESSION['surname'] = $row['surname'];
    }

如果我将 classes 中的代码放入 profile.php 脚本同时工作如果我使用 php class 它会给我错误在标题中。我希望你能明白我说的话。抱歉我的英语不好。

Answer 1

您不小心使用了 variable variable。

查看此演示：

<?php

class myclass {
  public $foo = 'foo';
  public $bar = 'bar';

  function __construct() {
  }

  function myfunc($foo) {
    echo "foo = {$this->foo}\n";
    echo "bar = {$this->bar}\n";
    echo "variable '$foo' = {$this->$foo}\n";
  }
}

$m = new myclass();

$m->myfunc('foo');
$m->myfunc('bar');
$m->myfunc('baz');

输出：

foo = foo
bar = bar
variable 'foo' = foo
foo = foo
bar = bar
variable 'bar' = bar
foo = foo
bar = bar
PHP Warning:  Undefined property: myclass::$baz in p.php on line 13

Warning: Undefined property: myclass::$baz in p.php on line 13
variable 'baz' =

结论：当你引用一个class成员变量时，如果你想直接引用该变量，不要使用第二个$。如果要使用可变变量，只使用第二个 $。即成员变量的名称在字符串变量中。

Fatal error: Uncaught Error: Call to a member function prepare()

Fatal error: Uncaught Error: Call to a member function prepare()

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