Fix seeddb netbox-edit form so that empty function field will remove …

…function info from netbox

changelog.d/2269.fixed.md

@@ -0,0 +1,3 @@
+Emptying the function field then clicking *Save* when editing a netbox
+actually removes the function for that netbox (as opposed to rejecting
+the change).

python/nav/web/seeddb/page/netbox/edit.py

@@ -290,6 +290,13 @@ def netbox_do_save(form):
         else:
             func.value = function
         func.save()
+    elif function == '':
+        try:
+            func = NetboxInfo.objects.get(netbox=netbox, variable='function')
+        except NetboxInfo.DoesNotExist:
+            pass
+        else:
+            func.delete()
 
     # Save the groups
     netboxgroups = form.cleaned_data['groups']

tests/integration/seeddb_test.py

@@ -6,7 +6,7 @@
 from mock import MagicMock
 
 from django.utils.encoding import smart_str
-from nav.models.manage import Netbox, Room
+from nav.models.manage import Netbox, Room, NetboxInfo
 from nav.web.seeddb.page.netbox.edit import netbox_edit, log_netbox_change
 from nav.web.seeddb.utils.delete import dependencies
 
@@ -110,3 +110,35 @@ def test_log_netbox_change_should_not_crash(admin_account, netbox):
     new.category_id = "OTHER"
 
     assert log_netbox_change(admin_account, old, new) is None
+
+
+def test_empty_function_field_in_netbox_edit_form_should_delete_respective_netboxinfo_instance(netbox, db, client):
+    """
+    Empty function fields in the webform should cause the function's
+    corresponding NetboxInfo to be deleted; This is the correct thing
+    to do because NAV prefills user forms with previously assigned
+    values. Hence, if NAV receives a form with an empty function
+    string, this means the user has explicitly cleared the function
+    string.
+    """
+    url = reverse('seeddb-netbox-edit', args=(netbox.id,))
+    def post(func):
+        return client.post(
+            url,
+            follow=True,
+            data={
+                "ip": netbox.ip,
+                "room": netbox.room_id,
+                "category": netbox.category_id,
+                "organization": netbox.organization_id,
+                "function": func,
+            },
+        )
+
+    assert len(NetboxInfo.objects.filter(netbox=netbox, variable='function')) == 0
+    post("")
+    assert len(NetboxInfo.objects.filter(netbox=netbox, variable='function')) == 0
+    post("foo")
+    assert NetboxInfo.objects.filter(netbox=netbox, variable='function').get().value == 'foo'
+    post("")
+    assert len(NetboxInfo.objects.filter(netbox=netbox, variable='function')) == 0