erp5_corporate_identity: support unobtainable creation dates (= None)

bt5/erp5_corporate_identity/SkinTemplateItem/portal_skins/erp5_corporate_identity/WebPage_viewAsLeaflet.py

@@ -56,8 +56,8 @@ leaflet_title = leaflet.getTitle()
 leaflet_relative_url = leaflet.getRelativeUrl()
 leaflet_language = leaflet.getLanguage()
 leaflet_creation_date = leaflet.getCreationDate()
-leaflet_date = leaflet_creation_date.strftime('%Y-%b')
-leaflet_year = leaflet_creation_date.strftime('%Y')
+leaflet_date = leaflet_creation_date.strftime('%Y-%b') if leaflet_creation_date else blank
+leaflet_year = leaflet_creation_date.strftime('%Y') if leaflet_creation_date else blank
 leaflet_reference = leaflet.getReference()
 leaflet_version = leaflet.getVersion() or "001"
 leaflet_aggregate_list = []

bt5/erp5_corporate_identity/SkinTemplateItem/portal_skins/erp5_corporate_identity/WebPage_viewAsRelease.py

@@ -60,7 +60,7 @@ release_creation_date = release.getCreationDate()
 release_modification_date = release.getModificationDate()
 release_aggregate_list = []
 release_relative_url = release.getRelativeUrl()
-release_creation_year = release_creation_date.strftime('%Y')
+release_creation_year = release_creation_date.strftime('%Y') if release_creation_date else blank
 #release_creation_month = release_creation_date.strftime('%b')
 #release_date = ''.join([release_creation_month, "-", release_creation_year])
 release_reference = release.getReference()

bt5/erp5_corporate_identity/SkinTemplateItem/portal_skins/erp5_corporate_identity/WebPage_viewAsSlideshow.py

@@ -201,7 +201,8 @@ doc_content = removeEmptyDetails(doc_dirty_content)
 doc_title = doc.getShortTitle() or doc.getTitle()
 doc_language = doc.getLanguage()
 doc_description = doc.getDescription()
-doc_creation_year = doc.getCreationDate().strftime('%Y')
+doc_creation_date = doc.getCreationDate()
+doc_creation_year = doc_creation_date.strftime('%Y') if doc_creation_date else blank
 doc_version = doc.getVersion() or "001"
 doc_reference = doc.getReference()
 doc_relative_url = doc.getRelativeUrl()