CategoryController Kaynak Kodlarıdır
<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\Category;
use Illuminate\Http\Request;
use DB;
class CategoryController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        $category = Category::all();
        return response()->json($category);
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        $validateData = $request->validate([
            'category_name' => 'required|unique:categories|max:255',
        ]);

        $category = new Category;
        $category->category_name = $request->category_name;

        $category->save();
    }

    /**
     * Display the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        $category = DB::table('categories')->where('id',$id)->first();
        return response()->json($category);
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, $id)
    {
        $data = array();
        $data['category_name'] =  $request->category_name;
        DB::table('categories')->where('id',$id)->update($data);
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function destroy($id)
    {
        DB::table('categories')->where('id',$id)->delete();
    }
}

Category Model Kodlarıdır
<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Category extends Model
{
    protected $fillable = [
        'category_name'
    ];
}

routes/api.php kodlarıdır
Route::apiResource('/test', 'Api\CategoryController');

create_category_table migration kodlarıdır
public function up()
    {
        Schema::create('categories', function (Blueprint $table) {
            $table->id();
            $table->string('category_name');
            $table->timestamps();
        });
    }