add get_export_form() to ExportMixin (#1409)

AUTHORS

@@ -122,4 +122,5 @@ The following is a list of much appreciated contributors:
 * josx (José Luis Di Biase)
 * Jan Rydzewski
 * 2ykwang (Yeongkwang Yang)
+* KamilRizatdinov (Kamil Rizatdinov)
 * Mark Walker

docs/changelog.rst

@@ -9,6 +9,7 @@ Changelog
 - Improve Korean translation (#1402)
 - Update example subclass widget code (#1407)
 - Drop support for python3.6, django 2.2, 3.0, 3.1 (#1408)
+- Add get_export_form() to ExportMixin (#1409)
 
 2.7.1 (2021-12-23)
 ------------------

import_export/admin.py

@@ -399,12 +399,19 @@ def get_export_context_data(self, **kwargs):
     def get_context_data(self, **kwargs):
         return {}
 
+    def get_export_form(self):
+        """
+        Get the form type used to read the export format.
+        """
+        return ExportForm
+
     def export_action(self, request, *args, **kwargs):
         if not self.has_export_permission(request):
             raise PermissionDenied
 
         formats = self.get_export_formats()
-        form = ExportForm(formats, request.POST or None)
+        form_type = self.get_export_form()
+        form = form_type(formats, request.POST or None)
         if form.is_valid():
             file_format = formats[
                 int(form.cleaned_data['file_format'])

tests/core/tests/test_mixins.py

@@ -6,7 +6,7 @@
 from django.test.testcases import TestCase
 from django.urls import reverse
 
-from import_export import formats, forms, mixins
+from import_export import admin, formats, forms, mixins
 
 
 class ExportViewMixinTest(TestCase):
@@ -203,3 +203,24 @@ def __init__(self):
         formats = m.get_export_formats()
         self.assertEqual(1, len(formats))
         self.assertEqual('CanExportFormat', formats[0].__name__)
+
+
+class ExportMixinTest(TestCase):
+    class TestExportMixin(admin.ExportMixin):
+        def __init__(self, export_form) -> None:
+            super().__init__()
+            self.export_form = export_form
+
+        def get_export_form(self):
+            return self.export_form
+
+    class TestExportForm(forms.ExportForm):
+        pass
+
+    def test_get_export_form(self):
+        m = admin.ExportMixin()
+        self.assertEqual(forms.ExportForm, m.get_export_form())
+
+    def test_get_export_form_with_custom_form(self):
+        m = self.TestExportMixin(self.TestExportForm)
+        self.assertEqual(self.TestExportForm, m.get_export_form())