Add first plot

nummi/main/models.py

@@ -194,7 +194,7 @@ class Snapshot(models.Model):
     @property
     def sum(self):
         if self.previous is None:
-            return None
+            return 0
         trans = self.transactions.aggregate(sum=models.Sum("value"))
         return trans["sum"] or 0
 
@@ -206,6 +206,24 @@ class Snapshot(models.Model):
             date__lte=self.date, date__gt=self.previous.date
         )
 
+    @property
+    def pos(self):
+        return (
+            self.transactions.filter(value__gt=0).aggregate(sum=models.Sum("value"))[
+                "sum"
+            ]
+            or 0
+        )
+
+    @property
+    def neg(self):
+        return (
+            self.transactions.filter(value__lt=0).aggregate(sum=models.Sum("value"))[
+                "sum"
+            ]
+            or 0
+        )
+
     class Meta:
         ordering = ["-date"]
         verbose_name = _("Snapshot")