CASCADE fixes in data model

core/models/survex.py

@@ -12,7 +12,11 @@ from django.urls import reverse
 
 
 class SurvexDirectory(models.Model):
-    path = models.CharField(max_length=200)
+    """This relates a Cave to the primary SurvexFile which is the 'head' of the survex tree for
+    that cave. Surely this could just be a property of Cave ? No. Several subdirectories
+    all relate to the same Cave
+    """
+    path = models.CharField(max_length=200) 
     cave = models.ForeignKey("Cave", blank=True, null=True, on_delete=models.SET_NULL)
     primarysurvexfile = models.ForeignKey(
         "SurvexFile", related_name="primarysurvexfile", blank=True, null=True, on_delete=models.SET_NULL
@@ -66,7 +70,10 @@ class SurvexFile(models.Model):
 
 class SurvexStationLookUpManager(models.Manager):
     """Don't know what this does, 
-    https://docs.djangoproject.com/en/dev/topics/db/managers/"""
+    https://docs.djangoproject.com/en/dev/topics/db/managers/
+    This changes the .objects thinggy to use a case-insensitive match name__iexact
+    so that now SurvexStation.objects.lookup() works as a case-insensitive match
+    """
     def lookup(self, name):
         blocknames, sep, stationname = name.rpartition(".")
         return self.get(block=SurvexBlock.objects.lookup(blocknames), name__iexact=stationname)
@@ -75,7 +82,7 @@ class SurvexStationLookUpManager(models.Manager):
 class SurvexStation(models.Model):
     name = models.CharField(max_length=100)
     block = models.ForeignKey("SurvexBlock", null=True, on_delete=models.SET_NULL)
-    objects = SurvexStationLookUpManager()
+    objects = SurvexStationLookUpManager() # overwrites SurvexStation.objects 
     x = models.FloatField(blank=True, null=True)
     y = models.FloatField(blank=True, null=True)
     z = models.FloatField(blank=True, null=True)
@@ -101,18 +108,22 @@ class SurvexStation(models.Model):
 #
 # Single SurvexBlock
 #
-class SurvexBlockLookUpManager(models.Manager):
-    """Don't know what this does,  
-    https://docs.djangoproject.com/en/dev/topics/db/managers/ """
-    def lookup(self, name):
-        if name == "":
-            blocknames = []
-        else:
-            blocknames = name.split(".")
-        block = SurvexBlock.objects.get(parent=None, survexfile__path=settings.SURVEX_TOPNAME)
-        for blockname in blocknames:
-            block = SurvexBlock.objects.get(parent=block, name__iexact=blockname)
-        return block
+# class SurvexBlockLookUpManager(models.Manager):
+    # """Don't know what this does,  
+    # https://docs.djangoproject.com/en/dev/topics/db/managers/ 
+    
+    # This changes the .objects_set thinggy to use a case-insensitive match name__iexact
+    # so that now SurvexBlock.objects.lookup() works as a case-insensitive match UNUSED
+    # """
+    # def lookup(self, name):
+        # if name == "":
+            # blocknames = []
+        # else:
+            # blocknames = name.split(".")
+        # # block = SurvexBlock.objects.get(parent=None, survexfile__path=settings.SURVEX_TOPNAME)
+        # for blockname in blocknames:
+            # block = SurvexBlock.objects.get(parent=block, name__iexact=blockname)
+        # return block
 
 
 class SurvexBlock(models.Model):
@@ -120,7 +131,7 @@ class SurvexBlock(models.Model):
     Multiple anonymous survex blocks are possible within the same surfex file
     """
 
-    objects = SurvexBlockLookUpManager()
+    # objects = SurvexBlockLookUpManager()
     name = models.CharField(max_length=100)
     title = models.CharField(max_length=200)
     parent = models.ForeignKey("SurvexBlock", blank=True, null=True, on_delete=models.SET_NULL)
@@ -163,10 +174,13 @@ class SurvexBlock(models.Model):
 
 
 class SurvexPersonRole(models.Model):
+    """The CASCADE means that if a SurvexBlock or a Person is deleted, then the SurvexPersonRole 
+    is deleted too
+    """
     survexblock = models.ForeignKey("SurvexBlock", on_delete=models.CASCADE)
     # increasing levels of precision, Surely we only need survexblock and person now that we have no link to a logbook entry?
     personname = models.CharField(max_length=100)
-    person = models.ForeignKey("Person", blank=True, null=True, on_delete=models.SET_NULL) # not needed
+    person = models.ForeignKey("Person", blank=True, null=True, on_delete=models.CASCADE) # not needed
     personexpedition = models.ForeignKey("PersonExpedition", blank=True, null=True, on_delete=models.SET_NULL)
 
     def __str__(self):