Added Classes for detecting Root Elements of Hamann-Collections

HaWeb/FileHelpers/XDocumentFileHelpers.cs

@@ -0,0 +1,38 @@
+namespace HaWeb.FileHelpers;
+using System.Xml.Linq;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using System.Text;
+using System.Xml;
+
+public static class XDocumentFileHelper {
+
+    private readonly static XmlReaderSettings _Settings = new XmlReaderSettings()
+    {
+        CloseInput = true,
+        CheckCharacters = false,
+        ConformanceLevel = ConformanceLevel.Fragment,
+        IgnoreComments = true,
+        IgnoreProcessingInstructions = true,
+        IgnoreWhitespace = false
+    };
+
+    public static async Task<XDocument?> ProcessStreamedFile(byte[] bytes, ModelStateDictionary modelState) {
+        try
+        {
+            using (var stream = new MemoryStream(bytes))
+            {
+                using (var xmlreader = XmlReader.Create(stream, _Settings))
+                {
+                    return XDocument.Load(xmlreader, LoadOptions.PreserveWhitespace | LoadOptions.SetLineInfo);
+
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            modelState.AddModelError("Error", $"Kein gültiges XML-Dokument geladen. Error: {ex.Message}");
+        }
+
+        return null;
+    }
+}