Request validation basics in Laravel - Step-by-Step Execution

Concept Flow - Request validation basics

User sends HTTP request

↓

Laravel receives request

↓

Controller method called

↓

Validate request data

↓

Process data

↓

Send response

This flow shows how Laravel handles a request by validating input data before processing or returning errors.

Execution Sample

Laravel

public function store(Request $request) {
  $validated = $request->validate([
    'name' => 'required|string|max:255',
    'email' => 'required|email',
  ]);
  // Process validated data
}

This code validates 'name' and 'email' fields from a request before processing.

Execution Table

Step	Action	Validation Rules	Input Data	Result	Next Step
1	Receive request	-	{name: 'Alice', email: '[e-mail]'}	Data received	Validate data
2	Validate 'name'	required|string|max:255	'Alice'	Pass	Validate 'email'
3	Validate 'email'	required|email	'[e-mail]'	Pass	Return validated data
4	Return validated data	-	-	{name: 'Alice', email: '[e-mail]'}	Process data
5	Process data	-	-	Data processed successfully	Send success response
6	Send response	-	-	Success response sent	END
7	If validation fails	-	{name: '', email: 'bademail'}	Fail	Return errors

💡 Validation passes or fails; if fails, errors returned; if passes, data processed and response sent.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
$request->name	'Alice'	'Alice'	'Alice'	'Alice'
$request->email	'[e-mail]'	'[e-mail]'	'[e-mail]'	'[e-mail]'
$validated	null	null	{name: 'Alice', email: '[e-mail]'}	{name: 'Alice', email: '[e-mail]'}

Key Moments - 2 Insights

Why does validation stop and return errors if a field is missing or invalid?

Because Laravel's validate() method checks each rule and immediately returns errors if any rule fails, as shown in execution_table row 7.

What happens to the $validated variable if validation fails?

It is never assigned because validate() throws an error and returns early, so $validated only has data if validation passes (rows 4 and 5).

Visual Quiz - 3 Questions

Look at the execution table, what is the result of validating the 'email' field at step 3?

A Pass

B Fail

C Skipped

D Error thrown

💡 Hint

Check the 'Result' column at step 3 in the execution_table.

At which step does Laravel return the validated data to the controller?

A Step 2

B Step 4

C Step 6

D Step 7

💡 Hint

Look for the step labeled 'Return validated data' in the execution_table.

If the 'name' field is empty, which step in the execution_table shows what happens next?

A Step 3

B Step 5

C Step 7

D Step 6

💡 Hint

Check the row where validation fails due to bad input.

Concept Snapshot

Laravel Request Validation Basics:
- Use $request->validate([...]) in controller.
- Define rules like 'required', 'string', 'email'.
- If validation fails, errors returned automatically.
- If passes, validated data returned for processing.
- Keeps input safe and app stable.

Full Transcript

In Laravel, when a user sends a request, the controller method receives it. The method calls $request->validate() with rules for each input field. Laravel checks each field against these rules. If all pass, the validated data is returned and the app processes it. If any rule fails, Laravel stops and returns error messages automatically. This protects the app from bad or missing data. The process flow is: receive request, validate data, if valid process it, else return errors. Variables like $request->name hold input values, and $validated holds the cleaned data after validation. Understanding this flow helps beginners see how Laravel keeps apps safe and user-friendly.

Practice

1. What is the main purpose of request validation in Laravel?

easy

A. To check user input early and ensure data is safe and correct

B. To speed up the server response time

C. To format the output HTML automatically

D. To connect to the database securely

Solution

1. Step 1: Understand request validation role

   Request validation checks user input before processing to avoid bad data.

2. Step 2: Identify main goal

   The main goal is to keep data safe and correct by stopping invalid input early.

3. Final Answer:

   To check user input early and ensure data is safe and correct -> Option A

4. Quick Check:

   Request validation = safe, correct input [OK]

Hint: Validation protects data by checking input early [OK]

Common Mistakes:

• Thinking validation speeds up server
• Confusing validation with output formatting
• Assuming validation manages database connections

2. Which of the following is the correct syntax to validate a request field named email as required and must be a valid email in a Laravel controller?

easy

A. $request->validate(['email' => 'required|email']);

B. $request->validate(['email' => 'email||required']);

C. $request->validate(['email' => 'required,email']);

D. $request->validate(['email' => ['required', email]]);

Solution

1. Step 1: Recall Laravel validation syntax

   Laravel uses pipe-separated strings for rules like 'required|email'.

2. Step 2: Check each option

   $request->validate(['email' => ['required', email]]);: syntax error ('email' not quoted in array). $request->validate(['email' => 'email||required']);: 'email||required' has empty invalid rule. $request->validate(['email' => 'required,email']);: uses comma which is invalid. $request->validate(['email' => 'required|email']);: correct pipe syntax.

3. Final Answer:

   $request->validate(['email' => 'required|email']); -> Option A

4. Quick Check:

   Pipe-separated rules = correct syntax [OK]

Hint: Use pipes '|' to separate validation rules in strings [OK]

Common Mistakes:

• Using commas instead of pipes
• Syntax errors in array rule lists
• Double pipes creating empty rules

3. Given this Laravel controller code snippet:

public function store(Request $request) {
    $validated = $request->validate([
        'age' => 'required|integer|min:18'
    ]);
    return $validated['age'];
}

What will be the output if the request sends age=20?

medium

A. Validation error: age is required

B. Validation error: age must be at least 18

C. null

D. 20

Solution

1. Step 1: Understand validation rules

   Field 'age' must be present, an integer, and minimum 18.

2. Step 2: Check input value

   Input age=20 meets all rules: present, integer, and >=18.

3. Step 3: Determine output

   Validation passes, so $validated['age'] returns 20.

4. Final Answer:

   20 -> Option D

5. Quick Check:

   Valid input returns value [OK]

Hint: Valid input passes and returns validated data [OK]

Common Mistakes:

• Assuming validation error for valid input
• Confusing min rule with max
• Expecting null when validation passes

4. Identify the error in this Laravel validation code:

public function update(Request $request) {
    $request->validate([
        'username' => 'required|min:5|max'
    ]);
}

medium

A. The 'required' rule cannot be combined with 'min'

B. The 'max' rule is missing a value, causing a syntax error

C. The 'min' rule should be 'min=5' instead of 'min:5'

D. The validate method should be called on the controller, not the request

Solution

1. Step 1: Review validation rules syntax

   Rules like 'min' and 'max' require a value after colon, e.g., 'max:10'.

2. Step 2: Identify error in code

   The 'max' rule is written without a value, which is invalid syntax.

3. Final Answer:

   The 'max' rule is missing a value, causing a syntax error -> Option B

4. Quick Check:

   Rules need values after colon [OK]

Hint: Always provide values for min/max rules after colon [OK]

Common Mistakes:

• Omitting values for min/max rules
• Using '=' instead of ':' in rules
• Calling validate on wrong object

5. You want to validate a request in Laravel where the password field is required, must be at least 8 characters, and must be confirmed by a matching password_confirmation field. Which validation rule set correctly enforces this?

hard

A. ['password' => 'required|confirmed', 'password_confirmation' => 'min:8']

B. ['password' => 'required|min:8', 'password_confirmation' => 'required']

C. ['password' => 'required|min:8|confirmed']

D. ['password' => 'required|min:8', 'password_confirmation' => 'same,password']

Solution

1. Step 1: Understand Laravel's confirmed rule

   The 'confirmed' rule checks if a matching field with '_confirmation' suffix exists and matches.

2. Step 2: Check each option

   ['password' => 'required|min:8|confirmed'] uses 'confirmed' with 'min:8' and 'required' on password only, which is correct. ['password' => 'required|min:8', 'password_confirmation' => 'required'] requires password_confirmation but does not check matching. ['password' => 'required|confirmed', 'password_confirmation' => 'min:8'] misplaces min:8 on confirmation. ['password' => 'required|min:8', 'password_confirmation' => 'same,password'] uses invalid 'password' rule.

3. Final Answer:

   ['password' => 'required|min:8|confirmed'] -> Option C

4. Quick Check:

   Use 'confirmed' rule for password confirmation [OK]

Hint: Use 'confirmed' rule to check matching confirmation field [OK]

Common Mistakes:

• Forgetting to add 'confirmed' rule
• Validating confirmation field separately
• Using 'same' instead of 'confirmed' rule