Umbraco-cms: Loss of Block List data after deleting and creating items

[HannesWinston]

The PostSave event does not include the value of a Block List after the deleting and creating Block List items.

Umbraco version

Umbraco v8.8.0

Reproduction

Bug summary

The deletion of an item in a Block List followed by publishing seems to break empty Block Lists on a page.

After the deletion of a Block List item, publishing and without reloading the page, adding new items to an empty list will result in those items not being saved on the page. But the publishing event is still successful, giving the editor the impression that the content was saved to the page when in in fact - it was not. This is an issue that can result in editors loosing data.

Specifics

As of now, I have found two ways to produce the error. The first way uses only one Block List property on a page, and the second uses two or more.

Tested in:

• Chrome v85.0.4183.121
• Edge v85.0.564.70
• Firefox v81.0.1

Steps to reproduce

Using a clean install of Umbraco v8.8.0 with starter kit.

1. Create a new Block List property on Document Type "Home".
2. Create a new Element Type containing a Textbox and add it to the newly created Block List.
3. Save Document Type and go to Content and edit the page "Home".
4. Add one item with any text to the Block List property and publish the page.
5. Delete the item and publish the page.
6. Without reloading the browser or going to another page and back to the page "Home", create a new item with any text and publish the page.
7. The page saves successfully, however the PostSave event does not send the correct Block List value
8. Reload the page.
9. The Block List property value is now empty, even though last published version should contain an item.

OR

1. Create two new Block List properties on Document Type "Home".
2. Create a new Element Type containing a Textbox and add it to both of the newly created Block List properties.
3. Save Document Type and go to Content and edit the page "Home".
4. Add two items with any text to the first Block List property and publish the page.
5. Delete one of the items in the first Block List, then create a new item in the second empty Block List.
6. Publish the page
7. The page saves successfully, however the PostSave event does not send the correct Block List value for the second Block List.
8. Reload the page.
9. The second Block List property value is now empty, even though last published version should contain an item.

Expected result

The Block List should contain the last published item.

Actual result

The Block List is empty and the PostSave event sends the following:
{"id":0,"alias":"blockList","value":""}

How to avoid

After deleting an item in a Block List, save the page and reload the browser.

---

_This item has been added to our backlog AB#8939_

[kjac]

Whoa. That's... weird! I can reproduce on vLatest. I'll have a look.

Thank you for a very detailed bug report ⭐

[kjac]

Well.. this isn't exactly simple. The error is periodic. I think @nielslyngsoe should get in on this.

[warrenbuckley]

Fixed & merged into v8/dev an upcoming 8.10.x release
Then cherry-picked into v8/8.7 abc42b5438dd64a4b5856d0a190787d1abc18d9d and is due for 8.8.1