Validate Source and TraderType values.

sage_validation/file_validator/forms.py

 """Forms for the file_validator app."""
 
 import csv
-from collections.abc import Sequence
+from collections.abc import Iterable, Sequence
 from typing import ClassVar
 
 from django import forms
@@ -69,6 +69,9 @@ class CSVUploadForm(forms.Form):
         fieldnames = reader.fieldnames if reader.fieldnames is not None else []
         self._validate_headers(fieldnames)
 
+        # Step 3: Validate 'Source' and 'SYSTraderTranType' values
+        self._validate_source_and_trader_type(reader)
+
         return file
 
     @staticmethod
@@ -108,3 +111,18 @@ class CSVUploadForm(forms.Form):
         if missing_columns:
             msg = f"Missing required columns: {', '.join(missing_columns)}"
             raise forms.ValidationError(msg)
+
+    @staticmethod
+    def _validate_source_and_trader_type(data: Iterable[dict]) -> None:
+        """Validate that 'Source' is always 80 and 'SYSTraderTranType' is always 4."""
+        errors = []
+
+        for index, row in enumerate(data, start=1):
+            if row.get("Source") != "80":
+                errors.append(f"Row {index}: 'Source' must be 80, but found {row.get('Source')}.")
+
+            if row.get("SYSTraderTranType") != "4":
+                errors.append(f"Row {index}: 'SYSTraderTranType' must be 4, but found {row.get('SYSTraderTranType')}.")
+
+        if errors:
+            raise forms.ValidationError(errors)