Custom validation rule for amount

app/Http/ValidationRules/ValidAmount.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www.elastic.co/licensing/elastic-license
+ */
+
+namespace App\Http\ValidationRules;
+
+use App\Libraries\MultiDB;
+use Illuminate\Contracts\Validation\Rule;
+
+/**
+ * Class ValidAmount.
+ */
+class ValidAmount implements Rule
+{
+    /**
+     * @param string $attribute
+     * @param mixed $value
+     * @return bool
+     */
+    public function passes($attribute, $value)
+    {
+        return (bool) is_float($value) || is_int($value);
+    }
+
+    /**
+     * @return string
+     */
+    public function message()
+    {
+        return ctrans('texts.invalid_amount');
+    }
+}

resources/lang/en/texts.php

@@ -4334,6 +4334,7 @@ $LANG = array(
     'clone_to_expense' => 'Clone to expense',
     'checkout' => 'Checkout',
     'acss' => 'Pre-authorized debit payments',
+    'invalid_amount' => 'Invalid amount. Number/Decimal values only.'
 );
 
 return $LANG;