Fix errors on serializing unsaved wikidata imports.

[redakcja.git] / src / catalogue / models.py

diff --git a/src/catalogue/models.py b/src/catalogue/models.py
index 92b2765..f9a2ecf 100644 (file)
--- a/src/catalogue/models.py
+++ b/src/catalogue/models.py
@@ -227,11 +227,15 @@ class Book(WikidataModel):
         return f'https://wolnelektury.pl/katalog/lektura/{self.slug}/'
     
     def authors_str(self):
+        if not self.pk:
+            return ''
         return ", ".join(str(author) for author in self.authors.all())
     authors_str.admin_order_field = 'authors__last_name'
     authors_str.short_description = _('Author')
 
     def translators_str(self):
+        if not self.pk:
+            return ''
         return ", ".join(str(author) for author in self.translators.all())
     translators_str.admin_order_field = 'translators__last_name'
     translators_str.short_description = _('Translator')