TUNGA CODE CHALLENGE

A program to import data from a large file into a database using PHP in Laravel.

Requirements:

• Clone the repo at https://github.com/webpriest/tunga-code-challenge.git.
• Run composer install to pull dependencies.
• Run npm install && npm run dev for the UI package.
• Change .env.example to .env and set DB_DATABASE=tunga_challenge.
• Run php artisan key:generate to generate the APP_KEY.
• Set QUEUE_CONNECTION=database in .env file
• Create database named tunga_code_challenge in MySQL or MariaDB, and run php artisan migrate to migrate tables to the just created database.
• Run command php artisan serve to boot up the local server.
• Access application with http://localhost:8000.
• **Open a new CLI and run php artisan queue:listen to process all jobs and listen for further jobs (keep it running for the entire process of testing).
• On loaded page in the browser, click the Choose file or Browse button to select a large JSON file.
• Click IMPORT FILE button to upload file for processing (this may take few seconds, and a notification will be sent to the UI confirming that a job queue is running in the background)

Code Implementation

The entry page is found at resources > views > index.blade.php. It contains a form with browse and submit buttons. The elements are represented by components created from Laravel Breeze.

It uses web routes located at *routes > web.php. There are two (2) routes included.

• A GET route to display the upload form
• A POST route to process the form request

The controller is located at app > Http > Controllers > ProfileController.php. This contains two (2) methods; index() and store(). The index method returns the view containing the form, while the store method receives and processes the form request.

A Service Container to process uploaded file is at app > Repositories > UploadRepository.php

Two Utility classes were added CardDigitChecker and DateFormatter in the Utils namespace

Processing the File Upload

A JSON file is sent to the store() method where there is an immediate test to verify that the file was sent. The process is outlined below:

• JsonMachine is a Laravel package for parsing unpredictably large JSON files. It parses a json array into the $profiles variable. One of the major advantages of using JsonMachine, is to mitigate the problems associated with uploading unpredictable file sizes. There is no need to adjust the memory limit in php.ini, as this kind of upload may be performed by a client whose action you cannot control.
• The file is immediately parsed via the dependency injection to the store method
• A try - catch block is used as a safety net for trying to process the records.
• The foreach loops through every record parsed from the JSON file.
• The records are encoded into JSON and decoded immediately into an associative array for extraction of each record to be persisted to the DB.
• Once decoded, it is sent as a job to the queue until all records have been captured from the JSON file. The challenge.json file used in the demo has about 10,000 records which took about 11 seconds to loop through (depending on speed of the machine).
• The method returns a success message to signify no error.

The Background Job Queue

The job is found in app > Jobs > ImportData.php. It takes a record as argument and uses the handle() method to queue the jobs. It first formats the date_of_birth via a custom DateFormatter class which converts date values to a database-friendly format, and determines the age using Carbon.

A control structure checks to see that the age is between 18 and 65 years. If true, the record is persisted to the database, otherwise, the record is ignored.

There are two (2) database tables; profiles and credit_cards tables. A one-to-one relationship exists between the models.

Best Practices

The SOLID principle was adhered to in completing the task.

• Each class was created for a single purpose.
• A class can be modified without breaking the code.
• Classes were abstracted as much as possible.
• The workflow implements the DRY principle.

Task Requirements

• Job termination can be mimicked using CTRL + C in the CLI where the php artisan queue:listen is running. Once stopped, restart server and re-run the queue:listen command to continue the jobs from where it stopped.
• Only records matching age between 18 and 65 are persisted to the database.

Bonus

• If the file size grows to a size 500 times the original size, the time complexity remains the same.
• The filter on the credit card to identify three (3) identical digits in sequence, requires a separate class that will be instantiated in the handler to explode every digit of the card number into an array, and compare the digits (using the array index to keep track of the last value). It compares the last value with the next and increments a counter. At the end of the loop, the iteration checks if the count is three (3) and returns true, otherwise false (though this was not implemented in the code, but the class was created in app > Utils > CardDigitChecker.php)

Author: Theophilus Aika

Slack: Theophilus Aika

"# tunga-challenge"