Cost units can be edited

app/Models/CostUnit.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Models;
+
+use App\Scopes\InstancedModel;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+/**
+ * @property string $name
+ * @property string $type
+ * @property string $billing_deadline
+ * @property string $distance_allowance
+ * @property boolean $mail_on_new
+ * @property boolean $allow_new
+ * @property boolean $archived
+ * @property Tenant $tenant
+ */
+class CostUnit extends InstancedModel
+{
+    protected $fillable = [
+        'name',
+        'tenant',
+        'type',
+        'billing_deadline',
+        'distance_allowance',
+        'mail_on_new',
+        'allow_new',
+        'archived',
+    ];
+
+    public function tresurers()  : BelongsToMany{
+        return $this->belongsToMany(User::class, 'cost_unit_treasurers', 'cost_unit_id', 'user_id')
+            ->withTimestamps();
+    }
+
+    public function resetTreasurers() {
+        $this->tresurers()->detach();
+        $this->save();
+    }
+}