项目const允许为空

app/Http/Requests/API/Project/CreateOrUpdateRequest.php

@@ -34,7 +34,7 @@ class CreateOrUpdateRequest extends FormRequest
                 'required',
                 'max:50',
             ],
-            'const' => 'numeric',
+            'const' => 'nullable|numeric',
             'begin' => 'required|date',
             'end' => 'required|date',
             'type' => 'required|max:20',