Update document size & hash when changing document file

Resolves #5704

CHANGELOG.txt

@@ -23,6 +23,7 @@ Changelog
  * Fix: Fixed incorrect HTML escaping of Jinja2 form templates for StructBlocks (Brady Moe)
  * Fix: All templates with wagtailsettings and modeladmin now use `block.super` for `extra_js` & `extra_css` (Timothy Bautista)
  * Fix: Layout issue when using FieldRowPanel with a heading (Andreas Bernacca)
+ * Fix: `file_size` and `file_hash` not updated when Document file changed (Andreas Bernacca)
 
 2.7 LTS (06.11.2019)
 ~~~~~~~~~~~~~~~~~~~~

docs/releases/2.8.rst

@@ -37,6 +37,7 @@ Bug fixes
  * Fixed incorrect HTML escaping of Jinja2 form templates for StructBlocks (Brady Moe)
  * All templates with wagtailsettings and modeladmin now use ``block.super`` for ``extra_js`` & ``extra_css`` (Timothy Bautista)
  * Layout issue when using FieldRowPanel with a heading (Andreas Bernacca)
+ * ``file_size`` and ``file_hash`` not updated when Document file changed (Andreas Bernacca)
 
 
 Upgrade considerations

wagtail/documents/tests/test_admin_views.py

@@ -321,6 +321,34 @@ class TestDocumentEditView(TestCase, WagtailTestUtils):
         self.assertContains(response, self.document.usage_url)
         self.assertContains(response, 'Used 0 times')
 
+    def test_reupload_different_file_size_and_file_hash(self):
+        """
+        Checks that reuploading the document file with a different file
+        changes the file size and file hash (see #5704).
+        """
+        # Build a fake file, and create it through the admin view
+        # since self.document doesn't have a file_size set.
+        fake_file = SimpleUploadedFile('some_file.txt', b'this is the content')
+        post_data = {
+            'title': "My doc",
+            'file': fake_file,
+        }
+        self.client.post(reverse('wagtaildocs:add'), post_data)
+
+        document = models.Document.objects.get(title="My doc")
+        old_file_size, old_file_hash = document.file_size, document.file_hash
+
+        new_file = SimpleUploadedFile(document.filename, b'less content')
+
+        self.client.post(reverse('wagtaildocs:edit', args=(document.pk,)), {
+            'title': document.title, 'file': new_file,
+        })
+
+        document.refresh_from_db()
+
+        self.assertNotEqual(document.file_size, old_file_size)
+        self.assertNotEqual(document.file_hash, old_file_hash)
+
     def test_reupload_same_name(self):
         """
         Checks that reuploading the document file with the same file name

wagtail/documents/views/documents.py

@@ -140,23 +140,27 @@ def edit(request, document_id):
         original_file = doc.file
         form = DocumentForm(request.POST, request.FILES, instance=doc, user=request.user)
         if form.is_valid():
-            doc = form.save()
             if 'file' in form.changed_data:
+                doc = form.save(commit=False)
                 doc.file_size = doc.file.size
 
                 # Set new document file hash
                 doc.file.seek(0)
                 doc._set_file_hash(doc.file.read())
                 doc.file.seek(0)
+                doc.save()
 
-                # if providing a new document file, delete the old one.
+                # If providing a new document file, delete the old one.
                 # NB Doing this via original_file.delete() clears the file field,
                 # which definitely isn't what we want...
                 original_file.storage.delete(original_file.name)
+            else:
+                doc = form.save()
 
             # Reindex the document to make sure all tags are indexed
             search_index.insert_or_update_object(doc)
 
+
             messages.success(request, _("Document '{0}' updated").format(doc.title), buttons=[
                 messages.button(reverse('wagtaildocs:edit', args=(doc.id,)), _('Edit'))
             ])