Improve Error class

import_export/resources.py

@@ -1,7 +1,6 @@
 import functools
 import inspect
 import logging
-import traceback
 from collections import OrderedDict
 from copy import deepcopy
 from html import escape
@@ -678,10 +677,7 @@ def after_init_instance(self, instance, new, row, **kwargs):
     def handle_import_error(self, result, error, raise_errors=False):
         logger.debug(error, exc_info=error)
         if result:
-            tb_info = traceback.format_exc()
-            result.append_base_error(
-                self.get_error_result_class()(error, traceback=tb_info)
-            )
+            result.append_base_error(self.get_error_result_class()(error))
         if raise_errors:
             raise exceptions.ImportError(error)
 
@@ -783,11 +779,8 @@ def import_row(self, row, instance_loader, **kwargs):
             # when only the original error is likely to be relevant
             if not isinstance(e, TransactionManagementError):
                 logger.debug(e, exc_info=e)
-            tb_info = traceback.format_exc()
             row_result.errors.append(
-                self.get_error_result_class()(
-                    e, traceback=tb_info, row=row, number=kwargs["row_number"]
-                )
+                self.get_error_result_class()(e, row=row, number=kwargs["row_number"])
             )
 
         return row_result

import_export/results.py

@@ -1,21 +1,42 @@
 import logging
+import sys
+import traceback
 from collections import OrderedDict
 
 from django.core.exceptions import NON_FIELD_ERRORS
 from django.utils.encoding import force_str
+from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 from tablib import Dataset
 
 logger = logging.getLogger(__name__)
 
 
 class Error:
-    def __init__(self, error, traceback=None, row=None, number=None):
+    def __init__(self, error, row=None, number=None):
         self.error = error
-        self.traceback = traceback
         self.row = row
         self.number = number
 
+    def __repr__(self):
+        result = f"<Error: {self.error!r}"
+        if self.row is not None:
+            result += f" at row {self.row}"
+        if self.number is not None:
+            result += f" at number {self.number}"
+        result += ">"
+        return result
+
+    @cached_property
+    def traceback(self):
+        if sys.version_info >= (3, 10):
+            lines = traceback.format_exception(self.error)
+        else:
+            lines = traceback.format_exception(
+                None, self.error, self.error.__traceback__
+            )
+        return "".join(lines)
+
 
 class RowResult:
     """Container for values relating to a row import."""

tests/core/tests/admin_integration/test_import.py

@@ -608,6 +608,7 @@ def test_result_error_display_traceback_only(self):
         self.assertNotIn("import-error-display-message", content)
         self.assertNotIn("import-error-display-row", content)
         self.assertIn("import-error-display-traceback", content)
+        self.assertIn("Traceback (most recent call last)", content)
 
 
 class ConfirmImportEncodingTest(AdminTestMixin, TestCase):

tests/core/tests/test_results.py

@@ -2,13 +2,48 @@
 
 from core.models import Book
 from django.core.exceptions import ValidationError
-from django.test.testcases import TestCase
+from django.test import SimpleTestCase
 from tablib import Dataset
 
 from import_export.results import Error, Result, RowResult
 
 
-class ResultTest(TestCase):
+class ErrorTest(SimpleTestCase):
+    def test_repr_no_details(self):
+        try:
+            1 / 0
+        except Exception as exc:
+            error = Error(exc)
+
+        self.assertEqual(repr(error), "<Error: ZeroDivisionError('division by zero')>")
+
+    def test_repr_all_details(self):
+        try:
+            1 / 0
+        except Exception as exc:
+            error = Error(exc, row=1, number=2)
+
+        self.assertEqual(
+            repr(error),
+            "<Error: ZeroDivisionError('division by zero') at row 1 at number 2>",
+        )
+
+    def test_traceback(self):
+        try:
+            1 / 0
+        except Exception as exc:
+            error = Error(exc)
+
+        self.assertTrue(
+            error.traceback.startswith("Traceback (most recent call last):\n")
+        )
+        self.assertIn(
+            "ZeroDivisionError: division by zero\n",
+            error.traceback,
+        )
+
+
+class ResultTest(SimpleTestCase):
     def setUp(self):
         self.result = Result()
         headers = ["id", "book_name"]