Convert backend of SubProject model to Eloquent

app/Models/Project.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\HasMany;
 
 /**
  * @property int $id
@@ -95,4 +96,12 @@ class Project extends Model
         'authenticatesubmissions',
         'viewsubprojectslink',
     ];
+
+    /**
+     * @return HasMany<SubProject>
+     */
+    public function subprojects(): HasMany
+    {
+        return $this->hasMany(SubProject::class, 'projectid', 'id');
+    }
 }

app/Models/SubProject.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+use Illuminate\Support\Carbon;
+
+/**
+ * @property int $id
+ * @property string $name
+ * @property int $projectid
+ * @property int $groupid
+ * @property string $path
+ * @property int $position
+ * @property Carbon $starttime
+ * @property Carbon $endtime
+ *
+ * @mixin Builder<SubProject>
+ */
+class SubProject extends Model
+{
+    protected $table = 'subproject';
+
+    public $timestamps = false;
+
+    protected $fillable = [
+        'name',
+        'projectid',
+        'groupid',
+        'path',
+        'position',
+        'starttime',
+        'endtime',
+    ];
+
+    protected $casts = [
+        'id' => 'integer',
+        'projectid' => 'integer',
+        'groupid' => 'integer',
+        'position' => 'integer',
+        'starttime' => 'datetime',
+        'endtime' => 'datetime',
+    ];
+
+    /**
+     * @return BelongsTo<Project, self>
+     */
+    public function project(): BelongsTo
+    {
+        return $this->belongsTo(Project::class, 'id', 'projectid');
+    }
+
+    /**
+     * Return the subprojects which depended upon this subproject on the specified date.
+     * If no date is provided, the current date is used.
+     *
+     * @return BelongsToMany<self>
+     */
+    public function children(?Carbon $date = null): BelongsToMany
+    {
+        if ($date === null) {
+            $date = Carbon::now()->setTimezone('UTC');
+        }
+
+        return $this->belongsToMany(SubProject::class, 'subproject2subproject', 'subprojectid', 'dependsonid')
+            ->wherePivot('starttime', '<=', Carbon::now()->setTimezone('UTC'))
+            ->where(function ($query) use ($date) {
+                $query->where('subproject2subproject.endtime', '>', $date)
+                    ->orWhere('subproject2subproject.endtime', '=', Carbon::create(1980));
+            });
+    }
+}