Query parameters in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

How does Laravel handle query parameters in routes?

Consider a Laravel route defined as Route::get('/search', function (Request $request) { return $request->query('q'); });. What will be the output if the URL is /search?q=books?

Laravel

Route::get('/search', function (Request $request) { return $request->query('q'); });

A "books"

B "q=books"

C null

D An error is thrown

💡 Hint

Think about how Laravel's query() method extracts values from the URL.

The query('q') method returns the value of the query parameter named 'q'. Since the URL has ?q=books, it returns "books".

📝 Syntax

intermediate

Which code correctly retrieves multiple query parameters in Laravel?

Given a URL /filter?category=books&sort=asc, which code snippet correctly retrieves both parameters?

A $params = $request->input(['category', 'sort']);

B $category = $request->query('category'); $sort = $request->query('sort');

C $category = $request->get('category'); $sort = $request->get('sort');

D $params = $request->query(); $category = $params['category']; $sort = $params['sort'];

💡 Hint

Remember that query() is the recommended method to get query parameters.

Option B uses query() to get each parameter individually, which is the correct and clear way. Option B uses input() which also works but is less specific. Option B uses get(), which also works but is less specific. Option B tries to get all parameters but then accesses them as an array which is valid but less direct.

🔧 Debug

advanced

Why does this Laravel code fail to get the query parameter?

Given the route and controller method below, why does $request->query('page') return null when accessing /items?page=2?

Route::get('/items', [ItemController::class, 'index']);

public function index(Request $request) {
    $page = $request->query('page');
    return $page;
}

A The route is missing a name, so query parameters are ignored.

B The query method only works for POST requests, not GET.

C The Request object is not imported or type-hinted correctly.

D The query parameter 'page' is not passed because the URL is malformed.

💡 Hint

Check if the Request class is properly imported and used.

If the Request class is not imported or the parameter is not type-hinted as Illuminate\Http\Request, Laravel won't inject the request object properly, so $request->query('page') returns null.

❓ state_output

advanced

What is the output of this Laravel controller method?

Consider this controller method:

public function show(Request $request) {
    $filters = $request->query();
    return json_encode($filters);
}

What is the output when accessing /show?color=red&size=medium?

A A JSON array: ["color", "red", "size", "medium"]

B An empty JSON object: "{}"

C A syntax error occurs

D {"color":"red","size":"medium"}

💡 Hint

Recall what $request->query() returns when called without arguments.

The query() method without arguments returns all query parameters as an associative array. Encoding it to JSON produces a JSON object with keys and values matching the URL parameters.

🧠 Conceptual

expert

Which statement about Laravel query parameters is true?

Choose the correct statement about how Laravel handles query parameters in HTTP requests.

A Laravel automatically merges query parameters and POST data, so <code>$request->input()</code> returns both.

B Query parameters can only be accessed via <code>$request->input()</code> and not <code>$request->query()</code>.

C The <code>$request->query()</code> method only returns query parameters if the route uses a GET method.

D Query parameters are not accessible in controller methods unless explicitly passed as route parameters.

💡 Hint

Think about how Laravel combines input sources.

Laravel's $request->input() method returns data from all input sources including query parameters and POST data. The query() method returns only query parameters. This merging happens regardless of the HTTP method.

Practice

1. What is the purpose of query parameters in a Laravel application URL?

easy

A. To define the database schema

B. To style the webpage with CSS

C. To send extra information to control the data returned by the server

D. To store user session data on the server

Solution

1. Step 1: Understand what query parameters do

   Query parameters are parts of the URL that send extra info to the server, usually after a question mark.

2. Step 2: Identify their use in Laravel

   In Laravel, query parameters help control what data the server returns based on the extra info sent.

3. Final Answer:

   To send extra information to control the data returned by the server -> Option C

4. Quick Check:

   Query parameters control returned data = B [OK]

Hint: Query parameters add info after ? in URL to filter data [OK]

Common Mistakes:

• Confusing query parameters with database schema
• Thinking query parameters style the page
• Assuming query parameters store session data

2. Which is the correct Laravel syntax to get a query parameter named page from a request?

easy

A. $request->param('page')

B. $request->input('page')

C. $request->getQuery('page')

D. $request->query('page')

Solution

1. Step 1: Recall Laravel method for query parameters

   Laravel uses $request->query('key') to get query parameters from the URL.

2. Step 2: Match the correct syntax

   Among options, only $request->query('page') correctly accesses the query parameter named 'page'.

3. Final Answer:

   $request->query('page') -> Option D

4. Quick Check:

   Use $request->query('key') for query params = A [OK]

Hint: Use $request->query('key') to get query params in Laravel [OK]

Common Mistakes:

• Using $request->input() which also works but includes POST data
• Using non-existent methods like getQuery or param
• Confusing query() with input() for query parameters

3. Given this Laravel route code:

Route::get('/search', function (Request $request) {
    $term = $request->query('term', 'default');
    return $term;
});

What will be the output if the URL is /search?term=laravel?

medium

A. laravel

B. default

C. null

D. term

Solution

1. Step 1: Understand query parameter retrieval with default

   The code uses $request->query('term', 'default'), which returns the 'term' parameter if present, else 'default'.

2. Step 2: Check the URL query parameter

   The URL has ?term=laravel, so 'term' is 'laravel', not missing.

3. Final Answer:

   laravel -> Option A

4. Quick Check:

   Query param 'term' present = 'laravel' [OK]

Hint: If query param exists, default is ignored [OK]

Common Mistakes:

• Assuming default value is always returned
• Confusing parameter name with its value
• Expecting null when parameter is present

4. Identify the error in this Laravel code snippet that tries to get a query parameter sort:

Route::get('/items', function (Request $request) {
    $sort = $request->query['sort'];
    return $sort;
});

medium

A. Request class not imported

B. Using array syntax instead of method call for query parameters

C. Incorrect route method; should be post() instead of get()

D. Missing semicolon after return statement

Solution

1. Step 1: Check how query parameters are accessed

   The code uses $request->query['sort'], which is incorrect because query is a method, not an array.

2. Step 2: Correct syntax for query parameters

   The correct way is $request->query('sort') to get the 'sort' parameter.

3. Final Answer:

   Using array syntax instead of method call for query parameters -> Option B

4. Quick Check:

   Use $request->query('key'), not $request->query['key'] [OK]

Hint: query() is a method, not an array; use parentheses [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Confusing get() with query() method
• Assuming query is a property, not a method

5. You want to get a query parameter filter in Laravel but provide a default value of all if it is missing or empty. Which code correctly handles this?

hard

A. $filter = $request->query('filter') ?: 'all';

B. $filter = $request->input('filter', 'all');

C. $filter = $request->query('filter', 'all');

D. $filter = $request->query('filter') ?? 'all';

Solution

1. Step 1: Understand default value behavior in query()

   The second argument in query('filter', 'all') returns 'all' only if the parameter is missing, but not if empty.

2. Step 2: Handle empty values as well

   Using $request->query('filter') ?: 'all' returns 'all' if the parameter is missing or empty (falsy).

3. Step 3: Check other options

   $filter = $request->input('filter', 'all'); uses input() which includes POST data, not just query. $filter = $request->query('filter') ?? 'all'; uses null coalescing which does not treat empty string as missing.

4. Final Answer:

   $filter = $request->query('filter') ?: 'all'; -> Option A

5. Quick Check:

   Use ?: to handle missing or empty query params = C [OK]

Hint: Use ?: to cover missing or empty query parameters [OK]

Common Mistakes:

• Assuming default in query() covers empty strings
• Using input() which mixes POST and query data
• Using ?? which ignores empty strings