fixing cyclic import problem

core/models/logbooks.py

@@ -21,7 +21,7 @@ from django.template import Context, loader
 from django.urls import reverse
 
 import settings
-#from troggle.core.models.caves import CaveSlug
+#from troggle.core.models.qm import CaveSlug
 from troggle.core.models.survex import SurvexStation
 from troggle.core.models.troggle import (DataIssue, Expedition, Person,
                                          PersonExpedition, TroggleModel)
@@ -113,6 +113,11 @@ class PersonTrip(TroggleModel):
     def __str__(self):
         return f'{self.personexpedition} ({self.logbook_entry.date})'
 
+class CaveSlug(models.Model):
+    cave = models.ForeignKey('Cave',on_delete=models.CASCADE)
+    slug = models.SlugField(max_length=50, unique = True)
+    primary = models.BooleanField(default=False)
+    
 class QM(TroggleModel):
     """This is based on qm.csv in trunk/expoweb/1623/204 which has the fields:
     "Number","Grade","Area","Description","Page reference","Nearest station","Completion description","Comment"