Do not allow self-referencing nav nodes

htmleditor/forms.py

@@ -88,6 +88,17 @@ class NavigationNodeAdminForm(forms.ModelForm):
 
         return name
 
+    def clean_parent(self):
+        """Do not allow self-referencing nodes"""
+        parent = self.cleaned_data['parent']
+
+        error_msg = "You can't have a node be its own parent."
+
+        if self.instance == parent:
+            raise forms.ValidationError(error_msg)
+
+        return parent
+
     def clean(self):
         "Check to make sure path is unique to prevent IntegrityError"
         cleaned_data = super(NavigationNodeAdminForm, self).clean()