Reflections Info Systems Php Full Stack Developer Interview Questions and Answers

I was assigned to implement basic CRUD operation in an API (the code should be production-ready). I was also instructed to perform Unit tests.

Q1. Laravel #1 - Why we use "composer.lock" file?
Ans. 
The composer.lock file is used to lock the exact versions of dependencies in a project to ensure consistent builds.
• Prevents different versions of dependencies from being installed on different machines

• Ensures that all developers are using the same versions of dependencies

• Helps in maintaining consistency and stability of the project
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Q2. Laravel #2 - When deleting a package from Vendor folder, will the application works?
Ans. 
Deleting a package from the Vendor folder can break the application if that package is required for functionality.
• Laravel uses Composer to manage dependencies, which are stored in the Vendor folder.

• If a package is deleted that is required by your application, you may encounter errors or missing functionality.

• For example, if you delete a package like 'guzzlehttp/guzzle' and your application makes HTTP requests using it,...read more
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Q3. Laravel #3 - How to write a custom authentication & middleware?
Ans. 
To write a custom authentication & middleware in Laravel, you can create a custom guard and middleware classes.
• Create a custom guard by extending the 'Illuminate\Auth\Guard' class and implementing the necessary methods like 'validate' and 'user'.

• Register the custom guard in the 'auth.php' configuration file.

• Create a custom middleware by extending the 'Illuminate\Auth\Middleware\Authenticate' class and implementing the ...read more
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Q4. Laravel #4 - How to handle custom request with Validations?
Ans. 
Custom requests with validations in Laravel can be handled using Form Requests.
• Create a new Form Request using artisan command: php artisan make:request CustomRequest

• Define validation rules in the authorize() and rules() methods of the CustomRequest class

• Inject the CustomRequest class into your controller method to automatically validate the incoming request
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Q5. Laravel #5 - Explain Polymorphism in relationship?
Ans. 
Polymorphism in Laravel relationships allows a model to belong to multiple other models.
• Polymorphic relationships allow a model to belong to multiple other models.

• It is useful when a model can belong to more than one other model.

• For example, a Comment model can belong to either a Post or a Video model.
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Q6. Laravel #6 - What is a Relationship?
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Q7. Laravel #7 - How to fetch 5 million records from 3 tables from a single DB in optimized way?
Ans. 
Use Laravel's Eloquent ORM with chunking and eager loading for optimized fetching of 5 million records from 3 tables in a single DB.
• Use Laravel's Eloquent ORM to fetch records efficiently

• Use chunking to process large datasets in smaller, manageable chunks

• Utilize eager loading to reduce the number of queries executed
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Q8. Laravel #8 - How to write a Unit test?
Ans. 
To write a unit test in Laravel #8, use PHPUnit and create test classes that extend the TestCase class.
• Create a new test class in the 'tests' directory.

• Extend the class with PHPUnit's TestCase class.

• Write test methods within the class to test specific functionality.

• Use assertions provided by PHPUnit to check if the code behaves as expected.

• Run the tests using the 'php artisan test' command.
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Q9. Laravel #9 - How to rollback for specific version in Migration ?
Ans. 
Use the migrate:rollback command with --step option to rollback to a specific version in Laravel migration.
• Use php artisan migrate:rollback --step=n command to rollback n number of migrations.

• Specify the number of migrations to rollback to a specific version.

• For example, php artisan migrate:rollback --step=3 will rollback the last 3 migrations.
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Q10. Laravel #10 - Difference between Session & Cookies ?
Ans. 
Sessions store data on the server side, while cookies store data on the client side.
• Sessions store data on the server side, while cookies store data on the client side.

• Sessions are more secure as the data is stored on the server and not accessible by the client.

• Cookies are limited in size (4KB) and can be disabled by the client, while sessions have no such limitations.
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Q11. Laravel #11 - How Laravel finds a specific session for each user?
Ans. 
Laravel uses a unique session identifier to find a specific session for each user.
• Laravel generates a unique session ID for each user upon login

• The session ID is stored in a cookie on the user's browser

• Laravel uses the session ID to retrieve the user's session data from the server
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Q12. Laravel #12 - Laravel Notifications, Different types of Mailers ?
Ans. 
Laravel Notifications allow you to send notifications across multiple channels. Different types of mailers in Laravel include SMTP, Mailgun, and Sendmail.
• Laravel Notifications can be sent through email, SMS, Slack, and more

• SMTP mailer is commonly used for sending emails in Laravel

• Mailgun is a popular mailer service that can be integrated with Laravel for sending emails

• Sendmail is another option for sending emails in La...read more
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Q13. Laravel #13 - How to send Asynchronous notification?
Ans. 
To send asynchronous notifications in Laravel, use queues to handle background processing.
• Use Laravel's built-in queue system to send notifications asynchronously.

• Define a notification class and use the ShouldQueue interface to indicate that the notification should be sent asynchronously.

• Dispatch the notification using the queue driver of your choice (e.g. database, Redis, Amazon SQS).
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Q14. Laravel #14 - How Queue works ?
Ans. 
Laravel Queue is a feature that allows you to delay the execution of a time-consuming task, improving application performance.
• Queues help in offloading time-consuming tasks to be processed in the background

• Tasks are added to the queue and processed by workers asynchronously

• Laravel provides drivers like Redis, Beanstalkd, and Amazon SQS for queue management
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Q15. Laravel #15 - How to Upgrade ?
Ans. 
To upgrade Laravel, you need to follow the official documentation and use Composer to update dependencies.
• Check the Laravel documentation for the specific version you are upgrading to

• Update your composer.json file with the new Laravel version

• Run 'composer update' command in your terminal to update dependencies

• Check for any deprecated features or changes in the new version and make necessary adjustments
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Q16. MySQL #1 - Why do we index in DB tables ?
Ans. 
Indexing in DB tables improves query performance by allowing the database to quickly locate specific rows.
• Indexes help in speeding up data retrieval operations by providing quick access to rows based on the indexed columns.

• They reduce the number of disk I/O operations required to fetch data, resulting in faster query execution.

• Indexes can also enforce uniqueness constraints and improve the efficiency of joins between t...read more
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Q17. Vue #1 - Why we use the "Key" - directive ?
Ans. 
The 'Key' directive in Vue is used to uniquely identify elements in a list to improve performance and prevent re-rendering.
• Helps Vue efficiently update the DOM by reusing existing elements instead of creating new ones

• Prevents unnecessary re-rendering of elements in a list when their order changes

• Improves performance by allowing Vue to track and update specific elements based on their keys

• Example:

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  Vue 3 is the latest version of Vue.js with improved performance, new features, and better TypeScript support.

  • Vue 3 uses a new reactivity system called the Composition API, which offers more flexibility and better organization of code compared to Vue 2's Options API.

  • Vue 3 introduces a new compiler that generates optimized code for better performance.

  • Vue 3 provides better TypeScript support with improved type inference a...read more

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Q19. Vue #3 - Options API vs Composition API ?
Ans. 
Options API is more verbose and flexible, while Composition API is more organized and reusable.
• Options API allows defining component options in separate sections like data, methods, computed, etc.

• Composition API allows organizing code based on logic and reusability with setup() function.

• Options API is suitable for smaller projects or when starting with Vue, while Composition API is recommended for larger projects or co...read more
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Q20. Vue #4 - How to use "env"?
Ans. 
The 'env' function in Vue is used to access environment variables in your application.
• Use process.env to access environment variables in Vue components

• Environment variables can be set in a .env file at the root of your project

• Remember to restart your development server after adding or changing environment variables
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Q21. Vue #5 - Why we using "Scope" in style?
Ans. 
Using 'Scope' in style allows us to apply styles to specific elements within a component.
• Scope in style allows us to target specific elements within a component without affecting others

• It helps in organizing and managing styles more efficiently

• Scope can be used to prevent styles from leaking out of a component
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Q22. Common #1 - What if an issue arise on a "Production" server that we can't troubleshoot in "Staging" or "Local", So how to fix that issue ?
Ans. 
In such cases, it is important to analyze the issue thoroughly on the production server and implement a fix cautiously.
• First, analyze the logs and error messages on the production server to understand the root cause of the issue.

• Check for any recent changes or updates that might have caused the problem.

• If possible, try to replicate the issue in a controlled environment like staging or local to further investigate.

• Consu...read more
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