Fetching Objects with PDO

PDO can hydrate query results as objects rather than associative arrays.

The examples focus on the operation itself, including the important distinction: FETCH_ASSOC returns arrays; FETCH_OBJ returns anonymous objects.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Before You Start

The examples use PHP 8.2+ features where shown. Database snippets require the corresponding PDO driver, demo tables, and credentials configured outside source code.

Example 1: Basic Use

FETCH_OBJ creates stdClass instances. Typed mapping should be explicit when application invariants matter.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->query("SELECT id, email FROM users ORDER BY id LIMIT 3");
while ($row = $stmt->fetch(PDO::FETCH_OBJ)) { echo $row->email . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 2: Checking Behavior

FETCH_OBJ creates stdClass instances. Typed mapping should be explicit when application invariants matter. FETCH_OBJ still returns objects regardless of the query ordering.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->query("SELECT id, email FROM users WHERE active=1 ORDER BY email LIMIT 4");
while ($row = $stmt->fetch(PDO::FETCH_OBJ)) { echo $row->email . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 3: Practical Example

FETCH_OBJ creates stdClass instances. Typed mapping should be explicit when application invariants matter. FETCH_OBJ still returns objects regardless of the query ordering.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->query("SELECT id, email FROM users ORDER BY email LIMIT 2");
while ($row = $stmt->fetch(PDO::FETCH_OBJ)) { echo $row->email . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Important Behavior and Edge Cases

FETCH_CLASS constructor/typing behavior requires attention; mapping deliberately is often clearer.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• PDO can hydrate query results as objects rather than associative arrays.
• FETCH_CLASS constructor/typing behavior requires attention; mapping deliberately is often clearer.
• FETCH_ASSOC returns arrays; FETCH_OBJ returns anonymous objects.

Use Fetching Objects with PDO when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.