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Fetch the complete documentation index at: https://mintlify.com/MonishAMPT/fastroute-code/llms.txt

Use this file to discover all available pages before exploring further.

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Introduction

Route parameters allow you to capture dynamic values from URLs. Instead of defining a separate route for every possible value, you can use parameter placeholders that match a pattern and extract the values for use in your handlers.

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Basic Parameter Syntax

Parameters are defined using curly braces {paramName} in your route pattern: 
$r->get('/user/{id}', 'get_user');
This will match /user/123, /user/abc, /user/anything.

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Regex Validation

FastRoute allows you to specify regex patterns to validate parameters using the syntax {paramName:pattern}: 
$r->get('/user/{id:\d+}', 'get_user');
This will only match /user/123 (digits), but not /user/abc.

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Real-World Examples

Here are examples from the source code showing different parameter patterns:

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Multiple Parameters

Capture multiple dynamic values in a single route:
api.php
$r->get('/api/test/{id:\d+}/test/{id2:\d+}', 'getid');
This route matches URLs like /api/test/123/test/456, capturing:
  • id = 123
  • id2 = 456
Both parameters use \d+ pattern, which matches one or more digits.

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DELETE with Parameter

Use parameters with different HTTP methods:
api.php
$r->delete('/api/test/delete/{id:\d+}', 'delete');
This matches DELETE /api/test/delete/42 and captures id = 42.

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POST with Parameter

Combine parameters with POST requests:
api.php
$r->post('/api/test/{test:\d+}', 'postdata');
This matches POST /api/test/789 and captures test = 789.

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Accessing Parameters in Handlers

When a route with parameters is matched, FastRoute passes an array of parameters to your handler:
index.php
function getid($var){
    if (is_array($var)) {
        $id = $var['id'];
        $id2 = $var['id2'];
    }
    echo "given id: ".$id;
    echo "given id: ".$id2;
}
The parameter array uses parameter names as keys:
  • $var['id'] - First parameter
  • $var['id2'] - Second parameter

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Single Parameter Handler

index.php
function delete($var){
    echo $var['id'];
}

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With POST Data

Combine route parameters with POST body data:
index.php
function postdata($var){
    echo $var['test'];
    $data = json_decode(file_get_contents('php://input'), true);
    echo json_encode($data);
}
Always check if $var is an array before accessing parameters to avoid errors when routes have no parameters.

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Common Regex Patterns

PatternDescriptionExample
\d+One or more digitsMatches: 123, 45678
\w+One or more word charactersMatches: abc, test_123
[0-9]+One or more numbersMatches: 123, 999
[a-z]+One or more lowercase lettersMatches: hello, world
[a-zA-Z]+One or more lettersMatches: Hello, WORLD
.+One or more of any characterMatches: anything

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Parameter Examples

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User ID (Numeric Only)

$r->get('/user/{id:\d+}', 'get_user');
// Matches: /user/123
// Doesn't match: /user/abc

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Username (Alphanumeric)

$r->get('/profile/{username:[a-zA-Z0-9_]+}', 'get_profile');
// Matches: /profile/john_doe123
// Doesn't match: /profile/john-doe

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Slug (Letters, numbers, hyphens)

$r->get('/post/{slug:[a-z0-9-]+}', 'get_post');
// Matches: /post/my-first-post
// Doesn't match: /post/My_Post

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Multiple Parameters Example

Here’s a detailed breakdown of the multi-parameter route:
api.php
$r->get('/api/test/{id:\d+}/test/{id2:\d+}', 'getid');
Request: GET /api/test/42/test/99 Captured Parameters: 
[
    'id' => '42',
    'id2' => '99'
]
Handler:
index.php
function getid($var){
    if (is_array($var)) {
        $id = $var['id'];      // '42'
        $id2 = $var['id2'];    // '99'
    }
    echo "given id: ".$id;     // given id: 42
    echo "given id: ".$id2;    // given id: 99
}

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Optional Parameters

FastRoute doesn’t support optional parameters directly. Instead, define multiple routes: 
$r->get('/user/{id:\d+}', 'get_user');
$r->get('/user', 'get_all_users');
Define more specific routes before less specific ones to ensure proper matching.

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Best Practices

Use regex patterns to ensure parameters match expected formats. This prevents invalid data from reaching your handlers.
Name parameters based on what they represent: {userId}, {postId}, {categorySlug} instead of generic names like {id} or {name}.
Always verify $var is an array before accessing parameters to handle routes without parameters gracefully.
Use the simplest regex pattern that meets your requirements. Complex patterns are harder to maintain.

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Next Steps

Route Groups

Combine parameters with route groups

Route Dispatcher

Understand how parameters are passed to handlers

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