PHP curl_multi_add_handle() Function: Usage and Examples

Adds a configured easy handle to a multi-transfer handle. This guide demonstrates its use in PHP code and explains when the result or side effect needs extra checks.

What It Does

Adds a configured easy handle to a multi-transfer handle.

Syntax and Parameters

The examples below show a real call to curl_multi_add_handle with suitable arguments. Read the function call in context: its connection, handle, input data or other prerequisites are created before use.

Requirements: cURL extension; HTTP client and transfer-handling tools.

Example 1: Core Behavior

The first case demonstrates the precise handle or result type.

<?php
$mh = curl_multi_init();
$handles = [];
foreach (['health', 'catalog'] as $path) {
    $ch = curl_init('https://api.example.test/' . $path);
    curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER => true, CURLOPT_TIMEOUT => 4]);
    curl_multi_add_handle($mh, $ch);
    $handles[] = $ch;
}
echo "Added " . count($handles) . " handles: " . (int) ($mh instanceof CurlMultiHandle);

Observe the returned value or changed resource state. A successful function call can still require additional checks before a higher-level operation is considered successful.

Example 2: Alternative or Failure Case

The second case checks behavior under a different configuration or request.

<?php
$mh = curl_multi_init();
$handles = [];
foreach (['health', 'catalog'] as $path) {
    $ch = curl_init('https://api.example.test/' . $path);
    curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER => true, CURLOPT_TIMEOUT => 5]);
    curl_multi_add_handle($mh, $ch);
    $handles[] = $ch;
}
echo "Added " . count($handles) . " handles: " . (int) ($mh instanceof CurlMultiHandle);

Compare the different inputs, environment assumptions or result checks. Do not use a transport-level success value as proof that all business-level requirements were met.

Practical Example: Applying the Rule

The practical case shows how to inspect the operation outcome instead of assuming success.

<?php
$mh = curl_multi_init();
$handles = [];
foreach (['health', 'catalog'] as $path) {
    $ch = curl_init('https://api.example.test/' . $path);
    curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER => true, CURLOPT_TIMEOUT => 6]);
    curl_multi_add_handle($mh, $ch);
    $handles[] = $ch;
}
echo "Added " . count($handles) . " handles: " . (int) ($mh instanceof CurlMultiHandle);

In an application, convert low-level failures into controlled responses and log only non-sensitive diagnostic context.

Important Behavior and Edge Cases

Adding a handle does not itself execute a request; drive the event loop afterward.

TLS validation, bounded timeouts and a destination allowlist are essential for network requests involving potentially untrusted targets.

Comparison with Related Functions or Patterns

Common Beginner Mistakes

Key Takeaways

• Adds a configured easy handle to a multi-transfer handle.
• Adding a handle does not itself execute a request; drive the event loop afterward.
• curl_multi_exec advances every handle registered in the multi stack.

Select this API or pattern based on its documented behavior and the trust boundaries in your own application, and test all external integrations against their actual deployments.