graph_editor: more robust BusinessProcess_getGraph

 - use relative url as key, not id/reference as it's not unique enough
 - support business link using non existent trade state ( for missing
paths in business template)

bt5/erp5_graph_editor/SkinTemplateItem/portal_skins/erp5_graph_editor/BusinessProcess_getGraph.py

@@ -18,7 +18,7 @@ def getBusinessProcessGraph(business_process):
 
 
   for trade_state in portal.portal_categories.trade_state.getCategoryChildValueList(): # XXX do we really want to display all trade states ?
-    state_id = trade_state.getReference() or trade_state.getId()
+    state_id = trade_state.getRelativeUrl()
     graph['node'][state_id] = dict(
         _class='erp5.business_process.trade_state',
         name=trade_state.getTranslatedTitle())
@@ -32,12 +32,17 @@ def getBusinessProcessGraph(business_process):
   visited_business_process_set.add(business_process)
   for link in business_process.contentValues(portal_type='Business Link'):
 
-    predecessor = 'start'
-    if link.getPredecessor():
-      predecessor = link.getPredecessorReference() or link.getPredecessorId()
-    successor = 'end'
-    if link.getSuccessor():
-      successor = link.getSuccessorReference() or link.getSuccessorId()
+    predecessor = link.getPredecessor() or 'start'
+    if predecessor not in graph['node']:
+      graph['node'][predecessor] = dict(
+        _class='erp5.business_process.trade_state',
+        name="missing trade state %s" % predecessor)
+
+    successor = link.getSuccessor() or 'end'
+    if successor not in graph['node']:
+      graph['node'][predecessor] = dict(
+        _class='erp5.business_process.trade_state',
+        name="missing trade state %s" % successor)
 
     graph['edge'][link.getRelativeUrl()] = dict(
         _class='erp5.business_process.business_link',
@@ -64,7 +69,7 @@ class_definition = {
     'properties': {
       'name': {'type': 'string', 'name': str(translateString('Name'))},
       'trade_phase': {'type': 'string', 'name': str(translateString('Trade Phase')), 'enum': [''] + [
-          trade_phase.getId() for trade_phase in portal.portal_categories.trade_phase.getCategoryChildValueList(local_sort_on=('int_index', 'title'))]}, 
+          trade_phase.getRelativeUrl() for trade_phase in portal.portal_categories.trade_phase.getCategoryChildValueList(local_sort_on=('int_index', 'title'))]},
     }
   }
 }