Global middleware in Laravel - Step-by-Step Execution

Concept Flow - Global middleware

Request enters Laravel

↓

Global Middleware runs

↓

Controller or Route executes

↓

Response generated

↓

Global Middleware runs on Response

↓

Response sent to client

Global middleware runs automatically on every HTTP request before and after the main route or controller handles it.

Execution Sample

Laravel

<?php
// app/Http/Kernel.php
protected $middleware = [
    \App\Http\Middleware\CheckForMaintenanceMode::class,
];

This code registers a global middleware that runs on every request to check if the app is in maintenance mode.

Execution Table

Step	Action	Middleware State	Request/Response	Notes
1	Request enters Laravel	No middleware run yet	Incoming HTTP Request	Start of request lifecycle
2	Global middleware CheckForMaintenanceMode runs	Middleware checks app status	Request passed through middleware	Middleware can block or allow request
3	Controller or Route executes	Middleware passed	Controller processes request	Main app logic runs
4	Response generated by controller	Middleware passed	Response object created	Response ready to send
5	Global middleware runs on Response	Middleware can modify response	Response passed back through middleware	Middleware can add headers or modify content
6	Response sent to client	Middleware finished	Final HTTP Response sent	Request lifecycle ends

💡 Response sent to client, request lifecycle complete

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
Request	Raw HTTP request	Checked for maintenance mode	Passed to controller	Passed back through middleware	Sent to client
Response	None	None	Created by controller	Modified by middleware	Final response sent

Key Moments - 3 Insights

Why does global middleware run on every request?

Because it is registered in the $middleware array in Kernel.php, Laravel automatically runs it for all requests as shown in execution_table steps 2 and 5.

Can global middleware stop a request before it reaches the controller?

Yes, as seen in step 2, middleware can block the request (for example, if the app is in maintenance mode) and prevent controller execution.

Does global middleware run on the response as well as the request?

Yes, step 5 shows middleware running on the response to modify it before sending to the client.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the controller process the request?

A Step 2

B Step 5

C Step 3

D Step 6

💡 Hint

Check the 'Action' column in execution_table row 3.

At which step does the global middleware check if the app is in maintenance mode?

A Step 1

B Step 2

C Step 4

D Step 5

💡 Hint

Look at the 'Middleware State' column in execution_table row 2.

If the middleware blocked the request at step 2, what would happen next?

A Response is generated immediately by middleware

B Controller runs anyway

C Request is sent to client without response

D Middleware runs again on response

💡 Hint

Refer to key_moments about middleware blocking requests before controller.

Concept Snapshot

Global middleware runs on every HTTP request in Laravel.
It is registered in app/Http/Kernel.php in the $middleware array.
Middleware runs before the controller and after response generation.
It can modify or block requests and responses.
Useful for tasks like maintenance mode checks or adding headers.

Full Transcript

Global middleware in Laravel is code that runs automatically on every HTTP request. When a request comes in, Laravel first runs all global middleware registered in the Kernel.php file. These middleware can check conditions like if the app is in maintenance mode and block the request if needed. If allowed, the request goes to the controller or route to generate a response. After the response is created, the global middleware runs again on the response to modify it if needed, such as adding headers. Finally, the response is sent back to the client. This process ensures middleware logic applies to all requests consistently.

Practice

1. What is the main purpose of global middleware in a Laravel application?

easy

A. To run code on every HTTP request to the application

B. To handle database migrations automatically

C. To define routes for the application

D. To manage user sessions only on login

Solution

1. Step 1: Understand what middleware does

   Middleware acts as a filter or layer that runs code before or after a request is handled.

2. Step 2: Identify the role of global middleware

   Global middleware runs on every HTTP request, applying tasks like authentication or logging universally.

3. Final Answer:

   To run code on every HTTP request to the application -> Option A

4. Quick Check:

   Global middleware = runs on every request [OK]

Hint: Global middleware affects all requests, not just some [OK]

Common Mistakes:

• Confusing middleware with routing
• Thinking middleware only runs on login
• Assuming middleware manages database

2. Which file in a Laravel project is used to register global middleware?

easy

A. config/app.php

B. routes/web.php

C. app/Http/Kernel.php

D. app/Providers/AppServiceProvider.php

Solution

1. Step 1: Recall where middleware is registered

   Middleware is registered in the Kernel class which manages HTTP middleware stacks.

2. Step 2: Identify the correct Kernel file

   In Laravel, the HTTP Kernel is located at app/Http/Kernel.php where global middleware is listed in the $middleware array.

3. Final Answer:

   app/Http/Kernel.php -> Option C

4. Quick Check:

   Global middleware registered in Kernel.php [OK]

Hint: Middleware registration is in Kernel.php, not routes or config [OK]

Common Mistakes:

• Choosing routes/web.php which defines routes only
• Confusing config/app.php with middleware registration
• Selecting service providers which are for services

3. Given this snippet in app/Http/Kernel.php:

$middleware = [
    \App\Http\Middleware\CheckAge::class,
];

What happens when a user sends a request to the app?

medium

A. The CheckAge middleware runs only on POST requests

B. The CheckAge middleware runs on every request

C. The CheckAge middleware runs only on routes with 'age' prefix

D. The CheckAge middleware does not run automatically

Solution

1. Step 1: Understand the $middleware array role

   The $middleware array in Kernel.php lists global middleware that runs on every request.

2. Step 2: Analyze the effect of adding CheckAge middleware there

   Since CheckAge is in $middleware, it will execute on all HTTP requests regardless of method or route.

3. Final Answer:

   The CheckAge middleware runs on every request -> Option B

4. Quick Check:

   $middleware = global middleware runs always [OK]

Hint: Middleware in $middleware runs on all requests, no exceptions [OK]

Common Mistakes:

• Thinking middleware runs only on certain HTTP methods
• Assuming middleware runs only on specific routes
• Believing middleware must be manually attached to routes

4. You added a new global middleware class to $middleware in app/Http/Kernel.php, but it does not run on requests. What is the most likely cause?

medium

A. The middleware class is registered in $routeMiddleware instead of $middleware

B. The middleware class is not imported in routes/web.php

C. The middleware class is missing a constructor

D. The middleware class does not implement the handle method

Solution

1. Step 1: Understand difference between $middleware and $routeMiddleware

   $middleware is for global middleware; $routeMiddleware is for middleware assigned to specific routes.

2. Step 2: Identify why middleware won't run globally

   If middleware is only registered in $routeMiddleware, it won't run on every request unless assigned to routes.

3. Final Answer:

   The middleware class is registered in $routeMiddleware instead of $middleware -> Option A

4. Quick Check:

   Global middleware must be in $middleware array [OK]

Hint: Global middleware must be in $middleware, not $routeMiddleware [OK]

Common Mistakes:

• Forgetting to implement handle method causes errors, not silent skip
• Importing middleware in routes/web.php is unnecessary
• Assuming constructor is required for middleware to run

5. You want to log every request's URL and method globally in your Laravel app. Which is the best way to do this using global middleware?

hard

A. Add logging code directly inside routes/web.php for each route

B. Register a route middleware and assign it to all routes manually

C. Use a controller constructor to log requests for each controller

D. Create a middleware with a handle method that logs request info and add it to $middleware in Kernel.php

Solution

1. Step 1: Identify how to apply logging globally

   Global middleware runs on every request, perfect for logging all requests centrally.

2. Step 2: Implement middleware and register globally

   Create middleware with a handle method that logs request URL and method, then add it to $middleware array in Kernel.php.

3. Step 3: Evaluate other options

   Logging in routes or controllers is repetitive and error-prone; assigning route middleware to all routes is inefficient.

4. Final Answer:

   Create a middleware with a handle method that logs request info and add it to $middleware in Kernel.php -> Option D

5. Quick Check:

   Global logging = global middleware in $middleware [OK]

Hint: Use global middleware for app-wide request logging [OK]

Common Mistakes:

• Logging inside routes causes duplication
• Controller constructors don't cover all requests
• Assigning route middleware manually is tedious and error-prone