Intervention model refactoring

* adds UserActionLogEntry model to user/models.py
  * wraps user and timestamp info
  * can be extended for more information in the future
* refactors all filtering and accessing on values

intervention/models.py

@@ -15,6 +15,7 @@ from intervention.settings import INTERVENTION_IDENTIFIER_LENGTH, INTERVENTION_I
 from konova.models import BaseObject, Geometry
 from konova.utils.generators import generate_random_string
 from organisation.models import Organisation
+from user.models import UserActionLogEntry
 
 
 class Intervention(BaseObject):
@@ -32,27 +33,35 @@ class Intervention(BaseObject):
     geometry = models.ForeignKey(Geometry, null=True, blank=True, on_delete=models.SET_NULL)
     documents = models.ManyToManyField("konova.Document", blank=True)
 
-    # Checks
-    checked_on = models.DateTimeField(default=None, null=True, blank=True)
-    checked_by = models.ForeignKey(User, null=True, blank=True, on_delete=models.SET_NULL, related_name='+')
-
     # Refers to "zugelassen am"
     registration_date = models.DateField(null=True, blank=True)
 
     # Refers to "Bestandskraft am"
     binding_on = models.DateField(null=True, blank=True)
 
+    # Checks - Refers to "Genehmigen" but optional
+    checked = models.OneToOneField(
+        UserActionLogEntry,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        help_text="Holds data on user and timestamp of this action",
+        related_name="+"
+    )
+
     # Refers to "verzeichnen"
-    recorded_on = models.DateTimeField(default=None, null=True, blank=True)
-    recorded_by = models.ForeignKey(User, null=True, blank=True, on_delete=models.SET_NULL, related_name='+')
+    recorded = models.OneToOneField(
+        UserActionLogEntry,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        help_text="Holds data on user and timestamp of this action",
+        related_name="+"
+    )
 
     # Holds which intervention is simply a newer version of this dataset
     next_version = models.ForeignKey("Intervention", null=True, blank=True, on_delete=models.DO_NOTHING)
 
-    # Compensation or payments, one-directional
-    #payments = models.ManyToManyField(Payment, related_name="+", blank=True)
-    #compensations = models.ManyToManyField(Compensation, related_name="+", blank=True)
-
     # Users having access on this object
     users = models.ManyToManyField(User)