base conversion classes for units #189

app/Support/Units/Velocity.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace App\Support\Units;
+
+/**
+ * Class Velocity
+ * @package App\Support\Units
+ */
+class Velocity extends \PhpUnitsOfMeasure\PhysicalQuantity\Velocity
+{
+    /**
+     * The unit that this is stored as
+     */
+    public const STORAGE_UNIT = 'knot';
+
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        $unit = setting('general.speed_unit');
+        $value = $this->toUnit($unit);
+        return (string) round($value, 2);
+    }
+
+    /**
+     * For the HTTP Resource call
+     */
+    public function toJson()
+    {
+        return [
+            'knot' => round($this->toUnit('knot'), 2),
+            'km/h' => round($this->toUnit('km/h'), 2),
+        ];
+    }
+}