Preparing Categories & Topics API

In this part, I’d like to focus on the backend side of our application and build the basic API for fetching categories and their related topics.

We’ll start this part by connecting to the database and creating the needed migrations. Then, we’ll prepare some seed data to load our database with. Then we’ll prepare the data that should be sent to the client (our SPA). After that, we’ll finish up by creating two API endpoints. One for fetching all categories, and the other to fetch all topics for each category.

Most of the content in this part should not feel new to you if you’re already a Laravel developer (you are, right?).

Setting up a database connection

Of course, our first step here is to set up a database connection. For this demo we’ll quickly set up a SQLite database.

Here’s how.

First, go to your .env file and change the database connection from mysql to sqlite.

DB_CONNECTION=sqlite

Then create the database by creating an empty database.sqlite file in the database directory. And you’re done!

The migrations

Our next step is to create the migrations for the categories & topics tables.

The categories table will basically have two fields: name and description — of course with the default id and timestamps fields.

So, create the migration — I’m using here a shortcut by creating the model with its migration at the same time.

php artisan make:model Category -m

Then go to the migration file and add the aforementioned fields:

public function up() { Schema::create('categories', function (Blueprint $table) { $table->increments('id'); $table->string('name')->unique(); $table->string('description'); $table->timestamps(); }); }

Now, let’s do the same for the topics table. It’ll have a title, body, category_id, and views (for number of views).

So, create it:

php artisan make:model Topic -m

And add the fields:

public function up() { Schema::create('topics', function (Blueprint $table) { $table->increments('id'); $table->integer('category_id')->unsigned(); $table->string('title'); $table->text('body'); $table->integer('views')->default(0); $table->timestamps(); $table->foreign('category_id') ->references('id')->on('categories') ->onDelete('cascade'); }); }

Finally, migrate the database:

php artisan migrate

Setting up the relations

Obviously, our next step is to set up the relationship between both models. It’s also obvious that the kind of relationship between them is 1-to-Many.

So, in the Category model you’d add this method:

public function topics() { return $this->hasMany(Topic::class); }

And for the Topic model you’d add this:

public function category() { return $this->belongsTo(Category::class); }

Seeding the database

To make our task in this project easier, we’re going to seed the database with some random data — and luckily Laravel makes it so easy.

To do that, we first have to define the needed model factories in /database/factories/ModelFactory.php.

$factory->define(App\Category::class, function (Faker\Generator $faker) { return [ 'name' => implode(' ', $faker->words(2)), 'description' => $faker->sentence(), ]; }); $factory->define(App\Topic::class, function (Faker\Generator $faker) { return [ 'category_id' => null, 'title' => $faker->sentence, 'body' => $faker->paragraph(7), 'views' => $faker->numberBetween(0, 10000), 'created_at' => $faker->datetimeBetween('-5 months'), ]; });

Next, create a seed class named CategoriesTopicsSeeder in the /database/seeds directory with this command:

php artisan make:seed CategoriesTopicsSeeder

Don't forget to run: composer dump-autoload afterwards.

Then, go to that seeder and put in the following code.

use App\Topic; use App\Category; use Illuminate\Database\Seeder; class CategoriesTopicsSeeder extends Seeder { /** * Run the database seeds. * * @return void */ public function run() { Topic::truncate(); Category::truncate(); factory(Category::class, 5)->create()->each(function($c) { $c->topics()->saveMany( factory(Topic::class, 5)->create([ 'category_id' => $c->id ]) ); }); } }

What this code does is create 5 categories with 5 topics for each one. And note that at the top we told it to clear the database each time we run the seeder; to prevent it from keeping the old seeded data.

Lastly, we have to register that seeder in our /database/seeds/DatabaseSeeder.php file.

public function run() { $this->call(CategoriesTopicsSeeder::class); }

Now you can seed the database with: php artisan db:seed. After that, your database should end up with 5 categories and 25 topics.

The data to be sent