Conditionality is broken when pagebreak is introduced

Just an update. I investigated and reproduced this bug. It is being caused by over-simplified logic in when to include a component on a page. When a component is hidden, but might be shown because it depends upon another component on the page, it is rendered and relies of javascript to hide it in the browser.

The checkbox is NOT included because it is hidden by a component on a previous page. The textfield IS included because it depends upon a component on this page, but that component was not rendered. Hence the javascript doesn't hide it.

Old behavior:

1) When determining whether a page is empty (and hence should be skipped by the next/prev page buttons), a field which depends upon at least one other field on the same page is considered shown. This causes pages to be displayed (such as in your example), when they shouldn't.

2) When determining whether to render a component on a page, if the component depends upon another component on the same page, it is always rendered, relying on the javascript to hide it. If, however, the source component was not rendered (because it depends solely upon components on other pages), then the javascript will be unable to hide it because the source component is missing from the page and cannot be triggered.

New behavior:

1) When determining whether a page is empty (and hence should be skipped by next/prev page), components which are currently hidden but depend upon other components are the same page are not considered shown. In your example, page two should not be shown at all if neither checkbox in field 1 is checked.

2) When determining whether a component should be rendered on a page, if the component would be hidden but depends upon at least one rendered component on the same page, it will be rendered. The javascript will then hide it.

The main bug in this issue is caused by the textfields depending upon the checkboxes (fields 2 and 4) which are absent from the form. Because they are absent, the javascript cannot trigger them to hide the text fields. With this patch, those text fields will not even be included on the form, unless their corresponding checkboxes are too.

This checking creates the possibility that determining the visibility of a component could cause an infinite loop due to cyclic dependencies in the conditions. This patch contains protection against this and will show the components should this (very unusual) situation occur.

3) If the visibility of a component has already been determined, it is cached and not determined again.

@petednz and others using conditions extensively - Please test this patch and let me know if it works for your complicated conditionals.

Bugger off, testbot.

@petednz -- let me know about your "very" complex form. And, yes, the patch is against the current -4.x-dev.

Committed to 7.x-4.x and 8.x.

Thanks to all for excellent support of this module.

I have a webform case using the matrix component where this still seems to occur despite Dan's patch. An export containing 2 variations on the problem is attached.

Clean install with:
Drupal 7.31
Views 7.x-3.8
Universally Unique ID 7.x-1.0-alpha5
Node clone 7.x-1.0-rc2
Node export 7.x-3.0
Webform 7.x-4.0-rc5+6-dev
Webform Matrix Component 7.x-4.x-dev
Webform Table Element 7.x-2.x-dev
Webform Validation 7.x-1.5

In the first case, the matrix component is on page 3, conditionally shown by a select on page 3. However, it still shows on page 1 and 2, and only is hidden properly on reaching the page where the select is rendered.

In the second case, the matrix component is shown conditionally by an "or" conditional that uses one select on page 1, and one select on page 3. In this case the matrix is hidden correctly on page 1, shows up on page 2, and hidden correctly again on page 3.

Perhaps this is unique to the matrix component in which case I am fine to move this comment to that issue queue. Thank you again!

Correct, sorry for not clarifying.