CASCADE fixes in data model

core/models/logbooks.py

@@ -17,7 +17,9 @@ todo = """
 
 
 class CaveSlug(models.Model):
-    """Moved here to avoid nasty cyclic import error"""
+    """Moved here to avoid nasty cyclic import error
+    CASCADE means that if the Cave is deleted, this is too
+    """
 
     cave = models.ForeignKey("Cave", on_delete=models.CASCADE)
     slug = models.SlugField(max_length=50, unique=True)
@@ -25,12 +27,13 @@ class CaveSlug(models.Model):
 
 
 class LogbookEntry(TroggleModel):
-    """Single parsed entry from Logbook"""
+    """Single parsed entry from Logbook
+    Gets deleted if the Expedition gets deleted"""
 
     date = (
         models.DateField()
     )  # MJG wants to turn this into a datetime such that multiple Logbook entries on the same day can be ordered.ld()
-    expedition = models.ForeignKey(Expedition, blank=True, null=True, on_delete=models.SET_NULL)  # yes this is double-
+    expedition = models.ForeignKey(Expedition, blank=True, null=True, on_delete=models.CASCADE)  # yes this is double-
     title = models.CharField(max_length=200)
     cave_slug = models.SlugField(max_length=50, blank=True, null=True)
     place = models.CharField(
@@ -84,6 +87,9 @@ class LogbookEntry(TroggleModel):
 class PersonLogEntry(TroggleModel):
     """Single Person going on a trip, which may or may not be written up.
     It could account for different T/U for people in same logbook entry.
+    
+    CASCADE means that if the personexpedition or the logbookentry is deleted,
+    then this PersonLogEntry is deleted too
     """
 
     personexpedition = models.ForeignKey("PersonExpedition", null=True, on_delete=models.CASCADE)