亚洲国产日韩欧美一区二区三区,精品亚洲国产成人av在线,国产99视频精品免视看7,99国产精品久久久久久久成人热,欧美日韩亚洲国产综合乱

Table of Contents
How to Use PDO Connection in Other Classes?
Understanding the Puzzling Error
Resolving the Issue
A Comprehensive Example
Home Backend Development PHP Tutorial How to Properly Use a PDO Connection Across Multiple Classes in PHP?

How to Properly Use a PDO Connection Across Multiple Classes in PHP?

Dec 21, 2024 am 12:50 AM

How to Properly Use a PDO Connection Across Multiple Classes in PHP?

How to Use PDO Connection in Other Classes?

Understanding the Puzzling Error

An error message stating "Uncaught Error: Call to undefined method Database::prepare()" may arise when attempting to use a PDO connection in a separate class. This error stems from a misunderstanding of how object-oriented programming (OOP) interconnects objects.

Resolving the Issue

1. Rethink Your Database Class:
The existing Database class serves no meaningful purpose. Instead, focus on creating a wrapper class if it extends PDO's functionality.

2. Establish a Central Database Connection:
Instantiate a standalone $db object using PDO or your enhanced database class. This single connection will serve as the cornerstone for all future database activities.

3. Pass the Connection as a Constructor Parameter:
Every class requiring database access should receive the $db connection as a constructor argument. This approach guarantees seamless access to the database throughout your entire application.

A Comprehensive Example

Consider the following improved codebase:

database.php:

$host = '127.0.0.1';
$db   = 'test';
$user = 'root';
$pass = '';
$charset = 'utf8';

$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$opt = [
    \PDO::ATTR_ERRMODE            => \PDO::ERRMODE_EXCEPTION,
    \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
    \PDO::ATTR_EMULATE_PREPARES   => false,
];
$pdo = new \PDO($dsn, $user, $pass, $opt);

user.php:

class User {
    /* Properties */
    private $conn;

    /* Get database access */
    public function __construct(\PDO $pdo) {
        $this->conn = $pdo;
    }

    /* List all users */
    public function getUsers() {
        return $this->conn->query("SELECT username, usermail FROM user")->fetchAll();
    }
}

app.php:

include 'database.php';
$user = new User($pdo);
$list = $user->getUsers();

foreach($list as $test) {
    echo $test["username"],"\n";
}

This refined codebase exemplifies the correct usage of PDO connections in multiple classes, ensuring error-free operation and elegant coding practices.

The above is the detailed content of How to Properly Use a PDO Connection Across Multiple Classes in PHP?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

php regex for password strength php regex for password strength Jul 03, 2025 am 10:33 AM

To determine the strength of the password, it is necessary to combine regular and logical processing. The basic requirements include: 1. The length is no less than 8 digits; 2. At least containing lowercase letters, uppercase letters, and numbers; 3. Special character restrictions can be added; in terms of advanced aspects, continuous duplication of characters and incremental/decreasing sequences need to be avoided, which requires PHP function detection; at the same time, blacklists should be introduced to filter common weak passwords such as password and 123456; finally it is recommended to combine the zxcvbn library to improve the evaluation accuracy.

PHP Variable Scope Explained PHP Variable Scope Explained Jul 17, 2025 am 04:16 AM

Common problems and solutions for PHP variable scope include: 1. The global variable cannot be accessed within the function, and it needs to be passed in using the global keyword or parameter; 2. The static variable is declared with static, and it is only initialized once and the value is maintained between multiple calls; 3. Hyperglobal variables such as $_GET and $_POST can be used directly in any scope, but you need to pay attention to safe filtering; 4. Anonymous functions need to introduce parent scope variables through the use keyword, and when modifying external variables, you need to pass a reference. Mastering these rules can help avoid errors and improve code stability.

How to handle File Uploads securely in PHP? How to handle File Uploads securely in PHP? Jul 08, 2025 am 02:37 AM

To safely handle PHP file uploads, you need to verify the source and type, control the file name and path, set server restrictions, and process media files twice. 1. Verify the upload source to prevent CSRF through token and detect the real MIME type through finfo_file using whitelist control; 2. Rename the file to a random string and determine the extension to store it in a non-Web directory according to the detection type; 3. PHP configuration limits the upload size and temporary directory Nginx/Apache prohibits access to the upload directory; 4. The GD library resaves the pictures to clear potential malicious data.

Commenting Out Code in PHP Commenting Out Code in PHP Jul 18, 2025 am 04:57 AM

There are three common methods for PHP comment code: 1. Use // or # to block one line of code, and it is recommended to use //; 2. Use /.../ to wrap code blocks with multiple lines, which cannot be nested but can be crossed; 3. Combination skills comments such as using /if(){}/ to control logic blocks, or to improve efficiency with editor shortcut keys, you should pay attention to closing symbols and avoid nesting when using them.

Tips for Writing PHP Comments Tips for Writing PHP Comments Jul 18, 2025 am 04:51 AM

The key to writing PHP comments is to clarify the purpose and specifications. Comments should explain "why" rather than "what was done", avoiding redundancy or too simplicity. 1. Use a unified format, such as docblock (/*/) for class and method descriptions to improve readability and tool compatibility; 2. Emphasize the reasons behind the logic, such as why JS jumps need to be output manually; 3. Add an overview description before complex code, describe the process in steps, and help understand the overall idea; 4. Use TODO and FIXME rationally to mark to-do items and problems to facilitate subsequent tracking and collaboration. Good annotations can reduce communication costs and improve code maintenance efficiency.

How Do Generators Work in PHP? How Do Generators Work in PHP? Jul 11, 2025 am 03:12 AM

AgeneratorinPHPisamemory-efficientwaytoiterateoverlargedatasetsbyyieldingvaluesoneatatimeinsteadofreturningthemallatonce.1.Generatorsusetheyieldkeywordtoproducevaluesondemand,reducingmemoryusage.2.Theyareusefulforhandlingbigloops,readinglargefiles,or

Quick PHP Installation Tutorial Quick PHP Installation Tutorial Jul 18, 2025 am 04:52 AM

ToinstallPHPquickly,useXAMPPonWindowsorHomebrewonmacOS.1.OnWindows,downloadandinstallXAMPP,selectcomponents,startApache,andplacefilesinhtdocs.2.Alternatively,manuallyinstallPHPfromphp.netandsetupaserverlikeApache.3.OnmacOS,installHomebrew,thenrun'bre

Learning PHP: A Beginner's Guide Learning PHP: A Beginner's Guide Jul 18, 2025 am 04:54 AM

TolearnPHPeffectively,startbysettingupalocalserverenvironmentusingtoolslikeXAMPPandacodeeditorlikeVSCode.1)InstallXAMPPforApache,MySQL,andPHP.2)Useacodeeditorforsyntaxsupport.3)TestyoursetupwithasimplePHPfile.Next,learnPHPbasicsincludingvariables,ech

See all articles