limit username length

src/ez_lan_manager/pages/RegisterPage.py

@@ -29,6 +29,11 @@ class RegisterPage(Component):
         except EmailNotValidError:
             self.email_input.is_valid = False
 
+    def on_user_name_input_change(self, _: TextInputChangeEvent) -> None:
+        current_text = self.user_name_input.text
+        if len(current_text) > UserService.MAX_USERNAME_LENGTH:
+            self.user_name_input.text = current_text[:UserService.MAX_USERNAME_LENGTH]
+
     async def on_submit_button_pressed(self) -> None:
         self.submit_button.is_loading = True
         await self.submit_button.force_refresh()
@@ -95,7 +100,8 @@ class RegisterPage(Component):
             margin_left=1,
             margin_right=1,
             margin_bottom=1,
-            grow_x=True
+            grow_x=True,
+            on_change=self.on_user_name_input_change
         )
         self.email_input = TextInput(
             label="E-Mail Adresse",