#169 Team delete-restore

* adds restorable delete functionality to Team model
* refactors minor code model parts by introducing DeletableObjectMixin
* only non-deleted Teams can be chosen for sharing
* deleted Teams can be restored using the proper function on the backend admin
* deleted Teams do not provide
* adds migration

konova/models/object.py

@@ -87,25 +87,15 @@ class BaseResource(UuidModel):
         super().delete()
 
 
-class BaseObject(BaseResource):
-    """
-    A basic object model, which specifies BaseResource.
+class DeletableObjectMixin(models.Model):
+    """ Wraps deleted field and related functionality
 
-    Mainly used for intervention, compensation, ecoaccount
     """
-    identifier = models.CharField(max_length=1000, null=True, blank=True)
-    title = models.CharField(max_length=1000, null=True, blank=True)
     deleted = models.ForeignKey("user.UserActionLogEntry", on_delete=models.SET_NULL, null=True, blank=True, related_name='+')
-    comment = models.TextField(null=True, blank=True)
-    log = models.ManyToManyField("user.UserActionLogEntry", blank=True, help_text="Keeps all user actions of an object", editable=False)
 
     class Meta:
         abstract = True
 
-    @abstractmethod
-    def set_status_messages(self, request: HttpRequest):
-        raise NotImplementedError
-
     def mark_as_deleted(self, user, send_mail: bool = True):
         """ Mark an entry as deleted
 
@@ -140,6 +130,25 @@ class BaseObject(BaseResource):
 
             self.save()
 
+
+class BaseObject(BaseResource, DeletableObjectMixin):
+    """
+    A basic object model, which specifies BaseResource.
+
+    Mainly used for intervention, compensation, ecoaccount
+    """
+    identifier = models.CharField(max_length=1000, null=True, blank=True)
+    title = models.CharField(max_length=1000, null=True, blank=True)
+    comment = models.TextField(null=True, blank=True)
+    log = models.ManyToManyField("user.UserActionLogEntry", blank=True, help_text="Keeps all user actions of an object", editable=False)
+
+    class Meta:
+        abstract = True
+
+    @abstractmethod
+    def set_status_messages(self, request: HttpRequest):
+        raise NotImplementedError
+
     def mark_as_edited(self, performing_user, request: HttpRequest = None, edit_comment: str = None):
         """ In case the object or a related object changed the log history needs to be updated
 
@@ -484,8 +493,8 @@ class ShareableObjectMixin(models.Model):
         Returns:
 
         """
-        directly_shared = self.users.filter(id=user.id).exists()
-        team_shared = self.teams.filter(
+        directly_shared = self.shared_users.filter(id=user.id).exists()
+        team_shared = self.shared_teams.filter(
             users__in=[user]
         ).exists()
         is_shared = directly_shared or team_shared
@@ -622,7 +631,9 @@ class ShareableObjectMixin(models.Model):
         Returns:
             teams (QuerySet)
         """
-        return self.teams.all()
+        return self.teams.filter(
+            deleted__isnull=True
+        )
 
     @abstractmethod
     def get_share_url(self):