php - PDO : Getting Error : Call to a member function prepare() on a non-object

Question

这个问题已经有答案了:

Reference - What does this error mean in PHP? (38 个回答)

已关闭 6 年前。

运行时 dbconfig.php (如下所述)出现错误:

PHP Fatal error:  Call to a member function prepare() on a non-object in Class.crud.php on line 13
PHP Stack trace:
PHP   1. {main}() dbconfig.php:0
PHP   2. crud->create() dbconfig.php:16

文件: dbconfig.php

<?php
   $db_host = "localhost";
   $db_user = "root";
   $db_pass = "95111991";
   $db_name = "php_pdo_db";

   try{
       $db_con = new PDO("mysql:host={$db_host}; dbname = {$db_name}",$db_user,$db_pass);
       $db_con->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
   }
   catch (PDOException $e){
       echo $e->getMessage();
   }
   include_once 'Class.crud.php';

   $crud = new crud($db_con);
?>

文件: Class.crud.php

<?php
 class crud
 {
     private $db;

     function _construct($db_con)
     {
         $this->db = $db_con;
     }
     public function create($fname,$lname,$email)
     {
         try{
             $stmt = $this->db->prepare("INSERT INTO tbl_user(Firstname,Lastname,Email) VALUES (:fname,:lname, :email)");
             $stmt ->bindparam(":fname", $fname);
             $stmt ->bindparam(":lname", $lname);
             $stmt ->bindparam(":email", $email);
             $stmt->execute();
             return true;
         }catch (PDOException $e){
             echo $e->getMessage();
             return false;
         }
     }
     public function getID($id){
         $stmt = $this->db->prepare("SELECT * FROM tbl_user WHERE ID = :id");
         $stmt->execute(array(":id"=>$id));
         $editRow=$stmt->fetch(PDO::FETCH_ASSOC);
         return $editRow;
     }
     public function update($id,$fname,$lname,$email)
     {
         try{
             $stmt=$this->db->prepare("UPDATE tbl_user SET Firstname = :fname,
                                  Lastname = :lname, Email = :email WHERE ID = :id");
             $stmt->bindparam(":fname",$fname);
             $stmt->bindparam(":lname",$lname);
             $stmt->bindparam(":email",$email);
             $stmt->bindparam(":id",$id);
             $stmt->execute();

             return true;
         }catch (PDOException $e){
             echo $e -> getMessage();
             return false;
         }
     }
     public function delete($id)
     {
         $stmt = $this->db->prepare("DELETE FROM tbl_user WHERE ID = :id");
         $stmt->bindparam(":id",$id);
         $stmt->execute();
         return true;
     }

     /* paging */
     public function dataview($query)
     {
         //global $db_con
         $stmt = $this->db->prepare($query);
         $stmt->execute();

         if($stmt->rowCount()>0){
             while($row=$stmt->fetch(PDO::FETCH_ASSOC))
             {
                 ?>
                  <tr>
                    <td><?php print($row['ID']); ?></td>
                    <td><?php print($row['Firstname']); ?></td>
                    <td><?php print($row['Lastname']); ?></td>
                    <td><?php print($row['Email']); ?></td>
                    <td align = "center">
                       <a href = "edit_data.php?edit_id=<?php print($row['ID']); ?>"><i class = "glyphicon glyphicon-edit"></i></a>
                    </td>
                    <td align = "center">
                       <a href = "delete_data.php?delete_id=<?php print($row['ID']); ?>"><i class = "glyphicon glyphicon-remove-circle"></i></a>
                    </td>
                    </tr>
                    <?php
             }
         }
         else{
             ?>
                  <tr>
                     <td>Nothing here...</td>
                  </tr>
                  <?php
         }
     }
     public function paging($query,$records_per_page)
     {
         $starting_position = 0;
         if(isset($_GET["page_no"]))
         {
             $starting_position = ($_GET["page_no"]-1)*$records_per_page;
         }
         $query2 = $query." limit $starting_position, $records_per_page";
         return $query2;
     }
     public function paginglink($query,$records_per_page)
     {
         $self = $_SERVER['PHP_SELF'];

         $stmt = $this->db->prepare($query);
         $stmt->execute();

         $total_no_of_records = $stmt->rowCount();

         if($total_no_of_records > 0){
             ?><ul class = "pagination"><?php
             $total_no_of_page = ceil($total_no_of_records/$records_per_page);
             $current_page = 1;
             if(isset($_GET["page_no"]))
             {
                 $current_page = $_GET["page_no"];
             }
             if($current_page != 1)
             {
                 $previous = $current_page-1;
                 echo "<li><a href = '".$self."?page_no=1'>First</a></li>";
                 echo "<li><a href = '".$self."?page_no=".$previous."'>Previous</a></li>";
             }
             for($i = 1; $i <= $total_no_of_page; $i++)
             {
                 if($i == $current_page)
                 {
                     echo "<li><a href = '".$self."?page_no=".$li."' style = 'color:red;'>".$i."</a></li>";
                 }
                 else{
                     echo "<li><a href = '".$self."?page_no=".$i."'>".$i."</a></li>";
                 }
             }
             if($current_page != $total_no_of_page)
             {
                 $next = $current_page+1;
                 echo "<li><a href = '".$self."?page_no=".$next."'>Next</a></li>";
                 echo "<li><a href = '".$self."?page_no=".$total_no_of_page."'>Last</a></li>";
             }
             ?></ul><?php
         }
     }
     /* paging */
 }
?>

如何解决此错误？

Answer 1

在您的class crud中，您已经编写了:

 function _construct($db_con)

使用__construct代替_construct

 function __construct($db_con)