CRUD with Eloquent in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Eloquent create operation?

Consider the following Laravel Eloquent code that creates a new user record. What will be the value of $user->name after running this code?

Laravel

<?php
$user = User::create(['name' => 'Alice', 'email' => '[e-mail]', 'password' => bcrypt('secret')]);
echo $user->name;

A An error because password is not fillable

B Alice

C secret

D null

💡 Hint

Remember that the create method returns the saved model instance with attributes filled.

The create method saves the record and returns the model instance with all attributes accessible. Since 'name' is set to 'Alice', echoing $user->name outputs 'Alice'.

❓ state_output

intermediate

What is the result of this update operation on Eloquent model?

Given this code snippet, what will be the value of $user->email after the update?

Laravel

<?php
$user = User::find(1);
$user->email = '[e-mail]';
$user->save();
echo $user->email;

A old email value

B null

C An error because save() was not called

D [e-mail]

💡 Hint

The save method commits changes to the database and updates the model instance.

After setting the email attribute and calling save(), the model instance reflects the updated email. So echoing $user->email outputs the new email.

📝 Syntax

advanced

Which option correctly deletes a user by ID using Eloquent?

You want to delete a user with ID 5. Which code snippet will successfully delete the user without errors?

A User::destroy(5);

B User::delete(5);

C User::find(5)->remove();

D User::find(5)->deleteUser();

💡 Hint

Check the correct static method for deleting by ID in Eloquent.

The destroy method deletes records by primary key. delete() is an instance method, not static. remove() and deleteUser() do not exist.

🔧 Debug

advanced

Why does this Eloquent update not change the database?

Look at this code snippet. The user's name is changed but the database does not update. What is the cause?

Laravel

<?php
$user = User::find(10);
$user->name = 'Bob';
// Missing save call

A Because save() was not called after changing the attribute

B Because find() returns null if user not found

C Because name is not a fillable attribute

D Because the database connection is not configured

💡 Hint

Changing attributes alone does not update the database without saving.

Eloquent requires calling save() to persist changes. Without save(), changes remain only in the model instance.

🧠 Conceptual

expert

What error occurs when trying to create a model without fillable attributes set?

Given a Laravel model with no $fillable or $guarded properties defined, what happens when you run User::create(['name' => 'Eve'])?

A A syntax error occurs

B The user is created successfully with name 'Eve'

C MassAssignmentException is thrown

D The create method returns null

💡 Hint

Laravel protects against mass assignment by default.

Without defining fillable or guarded, Laravel blocks mass assignment and throws a MassAssignmentException to prevent unsafe data insertion.

Practice

1. Which Eloquent method is used to add a new record to the database in Laravel?

easy

A. create()

B. find()

C. delete()

D. update()

Solution

1. Step 1: Understand the purpose of create()

   The create() method in Eloquent is designed to add a new record to the database by passing an array of attributes.

2. Step 2: Compare with other methods

   find() retrieves a record, delete() removes a record, and update() modifies an existing record. None of these add new records.

3. Final Answer:

   create() -> Option A

4. Quick Check:

   Add new record = create() [OK]

Hint: Use create() to add new data fast [OK]

Common Mistakes:

• Confusing find() with create()
• Using update() to add new records
• Trying to delete() to add data

2. Which of the following is the correct syntax to find a record by its ID using Eloquent?

easy

A. $user = User->find($id);

B. $user = User::findById($id);

C. $user = User::find($id);

D. $user = User.find($id);

Solution

1. Step 1: Recall Eloquent static method syntax

   Eloquent uses static methods on the model class, so User::find($id) is correct.

2. Step 2: Identify incorrect syntax

   User->find($id) is invalid because User is a class, not an object. findById() does not exist. User.find() is not PHP syntax.

3. Final Answer:

   $user = User::find($id); -> Option C

4. Quick Check:

   Find by ID uses ::find() [OK]

Hint: Use double colon :: for static methods [OK]

Common Mistakes:

• Using arrow -> on class name
• Calling non-existent findById() method
• Using dot . notation like JavaScript

3. What will be the output of this code snippet assuming a user with ID 5 exists?

$user = User::find(5);
if ($user) {
  $user->name = 'Alice';
  $user->save();
  echo 'Updated';
} else {
  echo 'Not found';
}

medium

A. Updated

B. Not found

C. Error: save() method missing

D. No output

Solution

1. Step 1: find(5) execution

   Since a user with ID 5 exists, User::find(5) returns an Eloquent model instance, making $user truthy.

2. Step 2: Update and save

   The if ($user) condition passes, so name is set to 'Alice', save() persists it to the database, and 'Updated' is echoed.

3. Final Answer:

   Updated -> Option A

4. Quick Check:

   Record found and saved = 'Updated' [OK]

Hint: If find() returns object, save() updates record [OK]

Common Mistakes:

• Assuming save() is missing
• Thinking find() throws error if no record
• Expecting no output when record exists

4. Identify the error in this code that tries to delete a user by ID:

$user = User::find($id);
$user->delete($id);

medium

A. delete() method does not exist in Eloquent

B. find() should be replaced with findOrFail()

C. You must call save() after delete()

D. delete() should be called without arguments

Solution

1. Step 1: Understand delete() method usage

   In Eloquent, delete() is called on the model instance without any arguments to remove that record.

2. Step 2: Identify the incorrect argument

   The code incorrectly passes $id to delete(), which expects no parameters. This causes an error.

3. Final Answer:

   delete() should be called without arguments -> Option D

4. Quick Check:

   delete() takes no parameters [OK]

Hint: Call delete() directly on model instance without args [OK]

Common Mistakes:

• Passing ID to delete() method
• Thinking delete() needs save() after
• Confusing delete() with static method

5. You want to update a user's email only if the user exists and the new email is not empty. Which code snippet correctly does this using Eloquent?

hard

A. $user = User::find($id);if ($newEmail) { $user->email = $newEmail; $user->save();}

B. $user = User::find($id);if ($user && !empty($newEmail)) { $user->email = $newEmail; $user->save();}

C. $user = User::findOrFail($id);$user->email = $newEmail;$user->save();

D. $user = User::where('id', $id)->update(['email' => $newEmail]);

Solution

1. Step 1: Check user existence and email validity

   $user = User::find($id);
   if ($user && !empty($newEmail)) {
     $user->email = $newEmail;
     $user->save();
   }

   checks if $user exists and $newEmail is not empty before updating, preventing errors or empty updates.

2. Step 2: Compare other options

   $user = User::find($id);
   if ($newEmail) {
     $user->email = $newEmail;
     $user->save();
   }

   skips user existence check, risking errors if user is null.

   $user = User::findOrFail($id);
   $user->email = $newEmail;
   $user->save();

   uses findOrFail() which throws exception if user missing, no email empty check.

   $user = User::where('id', $id)->update(['email' => $newEmail]);

   updates directly but does not check if $newEmail is empty.

3. Final Answer:

   $user = User::find($id);
   if ($user && !empty($newEmail)) {
     $user->email = $newEmail;
     $user->save();
   }

   -> Option B

4. Quick Check:

   Check user and email before save [OK]

Hint: Always check user exists and data valid before save [OK]

Common Mistakes:

• Not checking if user exists before update
• Skipping validation of new email
• Using findOrFail without handling exceptions