Query parameters in Laravel - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are query parameters in Laravel?

Query parameters are key-value pairs added to the URL after a question mark (?) to send data to the server, often used to filter or sort data.

beginner

How do you access query parameters in a Laravel controller?

You can access query parameters using the Request object, for example: $request->query('key') or $request->input('key').

intermediate

What method do you use to get all query parameters in Laravel?

Use $request->query() without arguments to get all query parameters as an associative array.

intermediate

How can you provide a default value for a missing query parameter in Laravel?

Use $request->query('key', 'default_value') to return 'default_value' if the query parameter 'key' is not present.

intermediate

How do you add query parameters to a URL in Laravel when generating links?

Use the route() helper with an array of parameters, or append query parameters with ->withQueryString() when redirecting.

Which symbol starts query parameters in a URL?

A ?

B #

C &

D /

Query parameters start after a question mark (?) in a URL.

How do you get a query parameter named 'page' in a Laravel controller?

A $request->query('page')

B All of the above

C $request->input('page')

D $request->get('page')

In Laravel, query(), get(), and input() can retrieve query parameters.

What does $request->query('sort', 'asc') do?

A Deletes 'sort' query parameter

B Sets 'sort' query parameter to 'asc'

C Gets 'sort' query parameter or returns 'asc' if missing

D Returns all query parameters

It fetches the 'sort' parameter or returns 'asc' if 'sort' is not present.

How can you keep existing query parameters when redirecting in Laravel?

A Manually append parameters to URL string

B Use route() helper without parameters

C Use $request->all()

D Use ->withQueryString() on the redirect

The withQueryString() method preserves current query parameters during redirects.

Which method returns all query parameters as an array?

A $request->query()

B $request->query('all')

C $request->all()

D $request->input()

$request->query() returns all query parameters as an associative array.

Explain how to retrieve and use query parameters in a Laravel controller.

Think about how Laravel handles incoming URL data.

Describe how to preserve query parameters when redirecting users in Laravel.

Consider user experience when filtering or paginating.

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