Created API endpoints

app/Models/Questionnaire.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class Questionnaire extends Model
+{
+    use SoftDeletes;
+
+    /**
+     * The attributes that should be mutated to dates.
+     *
+     * @var array
+     */
+    protected $dates = [
+        'updated_at',
+        'released_at',
+        'created_at',
+        'closed_at',
+        'reviewed_at',
+        'deleted_at'
+    ];
+
+    public function sections()
+    {
+        return $this->hasMany(Section::class);
+    }
+
+    public function questions()
+    {
+        return $this->hasManyThrough(Question::class, Section::class);
+    }
+
+    public function category()
+    {
+        return $this->belongsTo(Category::class);
+    }
+
+    public function creator()
+    {
+        return $this->belongsTo(User::class);
+    }
+}