Assignments Of Day 8 CRUD Operations with Eloquent

Assignments Of Day 8 

CRUD Operations with Eloquent

Assignment 1: Creating and Retrieving Users

Objective:

  • Create a User record.
  • Retrieve a user by their ID.
  • Display the user's name and email.

Steps:

1.  Create a new user in the database:

o    First, make sure that your User model is set up correctly to accept mass assignment by adding the $fillable property in the model.

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// In app/Models/User.php

class User extends Model

{

    protected $fillable = ['name', 'email', 'password'];

}

2.  Create a new user via a route or controller:

o    In your controller or route, you can create a new user by passing the necessary data to the create() method of the User model.

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// In web.php or UserController.php

use App\Models\User;

 

// Create a new user

$user = User::create([

    'name' => 'Alice Johnson',

    'email' => 'alice.johnson@example.com',

    'password' => bcrypt('password123'),

]);

3.  Retrieve a user by their ID:

o    Use the find() method to retrieve the user by their ID.

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// Retrieve the user with ID 1

$user = User::find(1);  // Assuming user ID 1 exists

 

// Display user name and email

echo "Name: " . $user->name . "<br>";

echo "Email: " . $user->email;

4.  Test the output:

o    If the user is found, you should see the following output:

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Name: Alice Johnson

Email: alice.johnson@example.com

Assignment 2: Updating a User’s Information

Objective:

  • Find a user by their ID.
  • Update their name and email.
  • Save the changes to the database.

Steps:

1.  Retrieve a user:

o    First, use find() to retrieve the user by their ID.

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$user = User::find(1);  // Assuming the user with ID 1 exists

2.  Modify the user's attributes:

o    Once you have the user object, you can modify any of its properties.

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$user->name = 'Updated Name';

$user->email = 'updated.email@example.com';

3.  Save the changes:

o    Use the save() method to persist the changes back to the database.

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$user->save();  // Save the updated user details

4.  Verify the update:

o    Retrieve the user again and display the updated details.

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$updatedUser = User::find(1);

echo "Updated Name: " . $updatedUser->name . "<br>";

echo "Updated Email: " . $updatedUser->email;

Expected Output:

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Updated Name: Updated Name

Updated Email: updated.email@example.com

Assignment 3: Deleting a User Record

Objective:

  • Retrieve a user by their ID.
  • Delete that user from the database.

Steps:

1.  Retrieve a user:

o    Use the find() method to retrieve a user.

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$user = User::find(1);  // Assuming the user with ID 1 exists

2.  Delete the user:

o    Use the delete() method to delete the user from the database.

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$user->delete();  // Delete the user from the database

3.  Verify deletion:

o    If you attempt to retrieve the user again, you should receive null since the record has been deleted.

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$deletedUser = User::find(1);  // This will return null if the user was deleted

if ($deletedUser === null) {

    echo "User has been deleted.";

} else {

    echo "User is still in the database.";

}

Expected Output:

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User has been deleted.

Assignment 4: Retrieve Users Based on a Condition

Objective:

  • Retrieve all users whose name is 'John Doe'.
  • Display their names and emails.

Steps:

1.  Use the where() method to filter the users:

o    You can use the where() method to retrieve users whose names are 'John Doe'.

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$users = User::where('name', 'John Doe')->get();  // Retrieve all users with the name 'John Doe'

2.  Display the results:

o    Loop through the retrieved users and display their names and emails.

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foreach ($users as $user) {

    echo "Name: " . $user->name . "<br>";

    echo "Email: " . $user->email . "<br><br>";

}

Expected Output (if there are users named 'John Doe'):

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Name: John Doe

Email: johndoe@example.com

 

Name: John Doe

Email: john.doe@anotherexample.com

Assignment 5: Update Multiple Records

Objective:

  • Update multiple users’ email addresses at once.
  • Use the where() method to target users whose names are 'John Doe'.

Steps:

1.  Use where() to filter users:

o    Retrieve all users whose name is 'John Doe'.

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$users = User::where('name', 'John Doe')->get();

2.  Loop through the users and update their email:

o    Iterate through the users and update their email address.

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foreach ($users as $user) {

    $user->email = 'newemail@example.com';  // Update email

    $user->save();  // Save the changes

}

3.  Verify the update:

o    After updating, retrieve the users again and display their updated email addresses.

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foreach ($users as $user) {

    echo "Updated Email: " . $user->email . "<br>";

}

Expected Output (if there are users named 'John Doe'):

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Updated Email: newemail@example.com

Updated Email: newemail@example.com

Assignment 6: Using Query Builder for Deletion

Objective:

  • Delete users whose names are 'John Doe' using the query builder.

Steps:

1.  Use the where() method with the query builder:

o    Use the User::where()->delete() chain to delete users whose names are 'John Doe'.

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User::where('name', 'John Doe')->delete();  // Delete all users named 'John Doe'

2.  Verify deletion:

o    After deletion, retrieve all users and check if any users named 'John Doe' remain.

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$users = User::where('name', 'John Doe')->get();

if ($users->isEmpty()) {

    echo "No users named 'John Doe' found.";

} else {

    echo "There are still users named 'John Doe'.";

}

Expected Output:

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No users named 'John Doe' found.

Conclusion:

These assignments will give you a strong foundation in performing basic CRUD operations using Laravel’s Eloquent ORM. Each assignment introduces a new concept, such as mass assignment, querying the database, updating records, and handling deletion. 

Assignment 7: Soft Deleting Users

Objective:

  • Implement soft deletes to mark a user as deleted without actually removing them from the database.
  • Retrieve users who are "soft deleted."

Steps:

1.  Enable Soft Deletes in the Model:

o    Open the User model and use the SoftDeletes trait to enable soft deletes.

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// In app/Models/User.php

use Illuminate\Database\Eloquent\SoftDeletes;

 

class User extends Model

{

    use SoftDeletes;  // Enable soft deletes

 

    protected $dates = ['deleted_at'];  // Specify the deleted_at field as a date

}

2.  Add the deleted_at column to the database:

o    If your table doesn't already have the deleted_at column, you can add it via a migration.

Run the migration command:

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php artisan make:migration add_deleted_at_to_users_table --table=users

Then, add the following line to the migration file:

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public function up()

{

    Schema::table('users', function (Blueprint $table) {

        $table->softDeletes();  // Add the 'deleted_at' column

    });

}

Run the migration:

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php artisan migrate

3.  Soft delete a user:

o    Use the delete() method to soft delete a user.

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$user = User::find(1);

$user->delete();  // This will mark the user as deleted, not remove from the DB

4.  Retrieve soft-deleted users:

o    To retrieve soft-deleted users, use the withTrashed() method.

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$deletedUsers = User::withTrashed()->get();

foreach ($deletedUsers as $user) {

    echo "User: " . $user->name . " (Deleted: " . $user->deleted_at . ")<br>";

}

5.  Restore a soft-deleted user:

o    To restore a soft-deleted user, use the restore() method.

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$user = User::withTrashed()->find(1);  // Retrieve the soft-deleted user by ID

$user->restore();  // Restore the user

6.  Verify the restoration:

o    After restoring, display the user’s details.

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$restoredUser = User::find(1);

echo "Restored User: " . $restoredUser->name;

Assignment 8: Using firstOrCreate and updateOrCreate

Objective:

  • Use firstOrCreate() to find or create a record.
  • Use updateOrCreate() to update an existing record or create a new one.

Steps:

1.  Using firstOrCreate() to find or create a user:

o    The firstOrCreate() method will check if a user with a specific email exists. If not, it will create one.

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$user = User::firstOrCreate(

    ['email' => 'newuser@example.com'], // Search condition

    ['name' => 'New User', 'password' => bcrypt('newpassword')] // Data to create if not found

);

Explanation: If the user with the email newuser@example.com exists, it will return the first matching record. If not, it will create a new user with the specified name and password.

2.  Using updateOrCreate() to update or create a user:

o    The updateOrCreate() method will look for an existing record and update it. If it doesn’t find one, it will create a new record.

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$user = User::updateOrCreate(

    ['email' => 'existinguser@example.com'], // Search condition

    ['name' => 'Updated User', 'password' => bcrypt('updatedpassword')] // Data to update or create

);

Explanation: If a user with the email existinguser@example.com exists, it will update their name and password. If not, a new user will be created with the given data.

Assignment 9: Mass Assignment for Creating Multiple Records

Objective:

  • Use mass assignment to create multiple users at once.

Steps:

1.  Ensure $fillable property is set up:

o    First, ensure that the User model has a $fillable property for mass assignment.

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// In app/Models/User.php

class User extends Model

{

    protected $fillable = ['name', 'email', 'password'];  // Allow mass assignment

}

2.  Create multiple users at once:

o    You can use the create() method within a loop or pass an array of data to insert() for bulk insertion.

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// Using a loop with create()

$users = [

    ['name' => 'User 1', 'email' => 'user1@example.com', 'password' => bcrypt('password1')],

    ['name' => 'User 2', 'email' => 'user2@example.com', 'password' => bcrypt('password2')],

    ['name' => 'User 3', 'email' => 'user3@example.com', 'password' => bcrypt('password3')],

];

 

foreach ($users as $userData) {

    User::create($userData);  // Insert each user record

}

3.  Bulk insert using insert():

o    For more efficient bulk insertion, you can use the insert() method, which avoids creating individual Eloquent models.

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User::insert([

    ['name' => 'User 4', 'email' => 'user4@example.com', 'password' => bcrypt('password4')],

    ['name' => 'User 5', 'email' => 'user5@example.com', 'password' => bcrypt('password5')],

    ['name' => 'User 6', 'email' => 'user6@example.com', 'password' => bcrypt('password6')],

]);

Assignment 10: Use pluck() to Retrieve Specific Columns

Objective:

  • Use the pluck() method to retrieve a single column of data from the database.

Steps:

1.  Retrieve a list of user emails:

o    Use pluck() to retrieve all user emails without retrieving other attributes.

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$emails = User::pluck('email');

foreach ($emails as $email) {

    echo $email . "<br>";

}

Explanation: The pluck() method returns an array containing the values of the specified column. In this case, we’re retrieving all the emails from the users table.

2.  Retrieve multiple columns:

o    If you want to retrieve multiple columns, you can pass an array to pluck().

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$userDetails = User::pluck('name', 'email');

foreach ($userDetails as $email => $name) {

    echo "Name: $name, Email: $email<br>";

}

Explanation: In this case, pluck() returns an associative array where the keys are the email addresses and the values are the corresponding user names.

Assignment 11: Count Records and Check Existence

Objective:

  • Count the number of records in a table.
  • Check if a specific user exists.

Steps:

1.  Count the total number of users:

o    Use the count() method to count the total number of records in the users table.

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$userCount = User::count();

echo "Total users: " . $userCount;

2.  Check if a user exists by email:

o    Use the exists() method to check if a user exists with a specific condition.

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$exists = User::where('email', 'john.doe@example.com')->exists();

if ($exists) {

    echo "User exists!";

} else {

    echo "User does not exist!";

}

Assignment 12: Using get() with Pagination

Objective:

  • Paginate results to display users in pages.

Steps:

1.  Retrieve users with pagination:

o    Use the paginate() method to retrieve users and paginate them.

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$users = User::paginate(5);  // Paginate users, 5 per page

foreach ($users as $user) {

    echo "Name: " . $user->name . "<br>";

}

2.  Display pagination links:

o    To display pagination links, you can call the links() method in your view.

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echo $users->links();

Explanation: The paginate() method will automatically handle the database query, limiting the results to the specified number of records per page (in this case, 5 users per page). The links() method will generate the necessary pagination controls.


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