in bibliography, journal name is null for patents

ippisite/ippidb/models.py

@@ -16,7 +16,7 @@ class Bibliography(models.Model):
     source = models.CharField('Bibliographic type', max_length=2, choices=SOURCES)
     id_source = models.CharField('Bibliographic ID', max_length=25)
     title = models.CharField('Title', max_length=300)
-    journal_name = models.CharField('Journal name', max_length=50)
+    journal_name = models.CharField('Journal name', max_length=50, null=True)
     authors_list = models.CharField('Authors list', max_length=500)
     biblio_year = models.PositiveSmallIntegerField('Year')
     cytotox = models.BooleanField('Cytotoxicity data', default=False)