Data loss using Preview on content types with image field.

Data loss during preview is major in my books

NodeForm/preview is node module so I reckon stick it there for now?

Data loss means critical

It's not just the alt field, the title field is also emptied when enabled. However, i cannot reproduce the loss of images. These are my steps to reproduce on current head (commit 8ba635b)

1. Edit article content type and make image field unlimited.
2. Add images and alt text to node, click Preview.
3. Go back, alt text is missing.
4. Add alt text again, click preview.
5. Go back, all is fine.

Trying to debug this.

Issue also occurs on fields with a limited cardinality.

Attached patch fixes the issue.

I confirm that the issue is still present.

I've tested the patch, and it fixes the issue (even if I can't really understand why this simple foreach fixes the issue).

We should be able to add a test for this I think, then we should be able to RTBC.

@Haza,

I agree tests should be added.

(even if I can't really understand why this simple foreach fixes the issue)

Hopefully the explanation below helps you understand.

+++ b/core/modules/node/src/NodeForm.php
@@ -83,7 +83,10 @@ public function form(array $form, FormStateInterface $form_state) {
-      $form_state = $preview;

+++ b/core/modules/node/src/NodeForm.php
@@ -83,7 +83,10 @@ public function form(array $form, FormStateInterface $form_state) {
+      foreach ($preview->getValues() as $name => $value) {
+        $form_state->setValue($name, $value);
+      }

Ho, I see now. Thanks for the explanations !

Working on a test

fail/pass

Code changes looks good just needs a manual testing and some minor feedback.

+++ b/core/modules/node/src/NodeForm.php
@@ -83,7 +83,10 @@ public function form(array $form, FormStateInterface $form_state) {
       /** @var $preview \Drupal\Core\Form\FormStateInterface */
-      $form_state = $preview;
+
+      foreach ($preview->getValues() as $name => $value) {
+        $form_state->setValue($name, $value);
+      }

A Comment here would help a lot.

Added beta-evaluation

While testing the patch, I found an other "issue" that is also fixed by the patch.

The issue

- Fresh D8 install
- Add Content > Article
- Fill the title, do not add an image, clic "preview"
- In the preview window, go back to the node edit page.
- Try to add an image, it silently fails.

Am I not able to reproduce this with the attached patch (that's why I do not create an other core issue), but maybe we could also add a test for this case ?

What do you think (leaving this as RTBC) ?

@Haza,

I think you should add a new issue for the issue you found and postpone it on this issue. We can then add the tests for it in that issue.

We have #2548713: Only one additional new value saved unlimited field and no non-field values are restored after preview for that one, see you over there :)

Awsome, thanks the link to the other issue.

Committed/pushed to 8.0.x, thanks!