Add visibility on invoices

Add links to invoices on transaction tables
Added invoices and has_invoice properties to transactions

nummi/main/models.py

@@ -59,6 +59,14 @@ class Transaction(models.Model):
     def __str__(self):
         return f"{self.date} – {self.name}"
 
+    @property
+    def invoices(self):
+        return Invoice.objects.filter(transaction=self)
+
+    @property
+    def has_invoice(self):
+        return self.invoices.count() > 0
+
     class Meta:
         ordering = ["-date"]
         verbose_name = _("Transaction")