Request Routing and Controllers: Core Concepts for Modern PHP Web Development

Build the mental model

Request Routing and Controllers focuses on this learner need: Map an incoming URL or navigation action to the correct handler or screen, preserve parameters, and define not-found or unauthorized behavior. Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence.

Track the changing state and identify the evidence that makes that state observable.

Identify the parts and boundaries

In Request Routing and Controllers, route pattern. Parameters. Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence.

1. 1

   Route pattern.

2. 2

   Parameters.

3. 3

   Handler/screen mapping.

4. 4

   404 and access behavior.

Trace one concrete case

Choose one realistic input for Request Routing and Controllers and trace it using this path lens: Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence. Predict the result before running the example, then compare prediction with evidence.

If the prediction fails, identify the assumption before changing the implementation.

REQUEST ROUTING AND CONTROLLERS
===============================
1. Route pattern.
2. Parameters.
3. Handler/screen mapping.
4. 404 and access behavior.
Evidence: the relevant output, test, log, query result, or rendered state for Request Routing and Controllers

Read the concept map, predict one concrete result, then compare that prediction with the module example or native tool.

A module-specific concept trace connecting core decisions to observable evidence.

practice/\n├── README.md\n├── request-routing-and-controllers-concept-map.txt\n└── evidence/\n    └── expected-result.txt

Compare a nearby alternative

For Request Routing and Controllers, compare the shown mechanism with a nearby alternative. Use this technical point—Handler/screen mapping.—inside this path context: Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence.

State the tradeoff in your own words.

Explain it back with evidence

Summarize Request Routing and Controllers without reading the example. Explain the input or state, operation or decision, and result through this implementation lens: Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence.

For Request Routing and Controllers, use this evidence standard: the relevant output, test, log, query result, or rendered state for Request Routing and Controllers. Interpret the evidence through this path context: Use Composer-managed PHP application boundaries, PSR-style HTTP requests and handlers, templates, PDO-backed domain data, validation, sessions/passwords, PHPUnit feedback, and deployment/security configuration as concrete evidence.

Common mistakes to avoid

• Route order or pattern conflict.
• Parameter type mismatch.
• Wrong base path.
• Missing 404 handling.