Moved the sort_post_txn_records utility and the logic to create the form to TransactionForm in the accounting application.

accounting/forms.py

@@ -24,7 +24,7 @@ from typing import Optional, List, Dict
 
 from django import forms
 from django.core.validators import RegexValidator
-from django.db.models import Q, Max
+from django.db.models import Q, Max, Model
 from django.db.models.functions import Length
 from django.utils.translation import gettext as _
 
@@ -234,6 +234,67 @@ class TransactionForm(forms.Form):
         self.txn_type = None
         self.transaction = None
 
+    @staticmethod
+    def from_post(post: Dict[str, str], txn_type: str, txn: Model):
+        TransactionForm._sort_post_txn_records(post)
+        form = TransactionForm(post)
+        form.txn_type = txn_type
+        form.transaction = txn
+        return form
+
+    @staticmethod
+    def _sort_post_txn_records(post: Dict[str, str]) -> None:
+        """Sorts the records in the form by their specified order, so that the
+        form can be used to populate the data to return to the user.
+
+        Args:
+            post: The POSTed form.
+        """
+        # Collects the available record numbers
+        record_no = {
+            "debit": [],
+            "credit": [],
+        }
+        for key in post.keys():
+            m = re.match(
+                "^(debit|credit)-([1-9][0-9]*)-(id|ord|account|summary|amount)",
+                key)
+            if m is None:
+                continue
+            record_type = m.group(1)
+            no = int(m.group(2))
+            if no not in record_no[record_type]:
+                record_no[record_type].append(no)
+        # Sorts these record numbers by their specified orders
+        for record_type in record_no.keys():
+            orders = {}
+            for no in record_no[record_type]:
+                try:
+                    orders[no] = int(post[F"{record_type}-{no}-ord"])
+                except KeyError:
+                    orders[no] = 9999
+                except ValueError:
+                    orders[no] = 9999
+            record_no[record_type].sort(key=lambda n: orders[n])
+        # Constructs the sorted new form
+        new_post = {}
+        for record_type in record_no.keys():
+            for i in range(len(record_no[record_type])):
+                old_no = record_no[record_type][i]
+                no = i + 1
+                new_post[F"{record_type}-{no}-ord"] = str(no)
+                for attr in ["id", "account", "summary", "amount"]:
+                    if F"{record_type}-{old_no}-{attr}" in post:
+                        new_post[F"{record_type}-{no}-{attr}"] \
+                            = post[F"{record_type}-{old_no}-{attr}"]
+        # Purges the old form and fills it with the new form
+        for x in [x for x in post.keys() if re.match(
+                "^(debit|credit)-([1-9][0-9]*)-(id|ord|account|summary|amount)",
+                x)]:
+            del post[x]
+        for key in new_post.keys():
+            post[key] = new_post[key]
+
     def clean(self):
         """Validates the form globally.