validate output file extension for output-format

commcare_export/cli.py

@@ -186,6 +186,12 @@ def main(argv):
 
     args = parser.parse_args(argv)
 
+    if args.output_format and args.output:
+        errors = []
+        errors.extend(_validate_output_filename(args.output_format, args.output))
+        if errors:
+            raise Exception(f"Could not proceed. Following issues were found: {', '.join(errors)}.")
+
     if not args.no_logfile:
         exe_dir = os.path.dirname(sys.executable)
         log_file = os.path.join(exe_dir, "commcare_export.log")
@@ -254,6 +260,23 @@ def main(argv):
             stats.print_stats(100)
 
 
+def _validate_output_filename(output_format, output_filename):
+    """
+    Validate file extensions for csv, xls and xlsx output formats.
+    Ensure extension unless using sql output_format.
+    """
+    errors = []
+    if output_format == 'csv' and not output_filename.endswith('.csv'):
+        errors.append("For output format as csv, output file name should have extension csv")
+    elif output_format == 'xls' and not output_filename.endswith('.xls'):
+        errors.append("For output format as xls, output file name should have extension xls")
+    elif output_format == 'xlsx' and not output_filename.endswith('.xlsx'):
+        errors.append("For output format as xlsx, output file name should have extension xlsx")
+    elif output_format != 'sql' and "." not in output_filename:
+        errors.append("Missing extension for filename")
+    return errors
+
+
 def _get_query(args, writer, column_enforcer=None):
     return _get_query_from_file(
         args.query,