# HG changeset patch
# User Goffi <goffi@goffi.org>
# Date 1566574046 -7200
# Node ID 4179ed660a85b917923f6e3ab44cb92974a0d1df
# Parent  ccb2a22ea0fc04d0645e053faad77ca189f709a5
backend: fixed publishing with "consistent_publisher" when no item was previously available

diff -r ccb2a22ea0fc -r 4179ed660a85 sat_pubsub/backend.py
--- a/sat_pubsub/backend.py	Fri Aug 16 12:53:33 2019 +0200
+++ b/sat_pubsub/backend.py	Fri Aug 23 17:27:26 2019 +0200
@@ -457,19 +457,22 @@
                 if affiliation == 'owner' or self.isAdmin(requestor):
                     if configuration[const.OPT_CONSISTENT_PUBLISHER]:
                         pub_map = yield node.getItemsPublishers(itemIdentifiers)
-                        publishers = set(pub_map.values())
-                        if len(publishers) != 1:
-                            # TODO: handle multiple items publishing (from several
-                            #       publishers)
-                            raise error.NoPublishing(
-                                "consistent_publisher is currently only possible when "
-                                "publishing items from a single publisher. Try to "
-                                "publish one item at a time")
-                        # we replace requestor and new payload's publisher by original
-                        # item publisher to keep publisher consistent
-                        requestor = publishers.pop()
-                        for item in items:
-                            item['publisher'] = requestor.full()
+                        if pub_map:
+                            # if we have existing items, we replace publishers with
+                            # original one to stay consistent
+                            publishers = set(pub_map.values())
+                            if len(publishers) != 1:
+                                # TODO: handle multiple items publishing (from several
+                                #       publishers)
+                                raise error.NoPublishing(
+                                    "consistent_publisher is currently only possible when "
+                                    "publishing items from a single publisher. Try to "
+                                    "publish one item at a time")
+                            # we replace requestor and new payload's publisher by original
+                            # item publisher to keep publisher consistent
+                            requestor = publishers.pop()
+                            for item in items:
+                                item['publisher'] = requestor.full()
                 else:
                     # we don't want a publisher to overwrite the item
                     # of an other publisher