[wp-trac] [WordPress Trac] #41502: _wp_expand_nav_menu_post_data() corrupts multiple select (array value)

[WordPress Trac]

#41502: _wp_expand_nav_menu_post_data() corrupts multiple select (array value)
--------------------------------------+------------------------------
 Reporter:  elliotcondon              |       Owner:
     Type:  defect (bug)              |      Status:  new
 Priority:  normal                    |   Milestone:  Awaiting Review
Component:  Menus                     |     Version:  4.9
 Severity:  normal                    |  Resolution:
 Keywords:  has-patch has-unit-tests  |     Focuses:  administration
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Comment (by elliotcondon):

 Hi @dd32

 Thanks for the reply, I've glad you were able to replicate the issue.
 This patch looks to be working for the basic example, but not for more
 complicated scenarios.

 Testing the basic example, everything looks to be working well:

 {{{
 <input type="text" name="testing[]" value="A">
 <input type="text" name="testing[]" value="B">

 Result:

 [testing] => Array
         (
             [0] => A
             [1] => B
         )

 }}}

 However, there is another scenario where an issue occurs (slightly more
 complicated, but just as common). When working on a plugin, it is best
 practice to 'namespace' your $_POST data by writing input names like
 `my[field_1]`;

 I have found the following 2 issues:

 '''Issue 1. Extra $_POST data.'''
 When using a name-spaced input name, the $_POST data contains an extra
 value. Note the 3rd bit of data is a duplicate:

 {{{
 <input type="checkbox" name="my[field_1][]" value="A"> A
 <input type="checkbox" name="my[field_1][]" value="B"> B

 Result:

 [my] => Array
         (
             [field_1] => Array
                 (
                     [0] => A
                     [1] => B
                     [] => B
                 )

         )

 }}}

 '''Issue 2. Hidden input breaks $_POST data.'''
 When adding a list of checkbox or radio inputs, it is common to use a
 hidden input above the list to allow an "empty" value to be saved. Doing
 so prevents the array data from being interpreted:

 {{{
 <input type="hidden" name="my[field_1]" value="">
 <input type="checkbox" name="my[field_1][]" value="A"> A
 <input type="checkbox" name="my[field_1][]" value="B"> B

 Result:

     [my] => Array
         (
             [field_1] => Array
                 (
                     [] => B
                 )

         )

 }}}

 Let me know how you go testing these 2 scenarios. Happy to help provide
 any other info.

 Question. Why do we need such a complicated
 _wp_expand_nav_menu_post_data() function? If the form data is encoded into
 a JSON string and sent via `$_POST['nav-menu-data']`, can't we just decode
 this string and replace `$_POST['nav-menu-data']` with the array value?


 Thanks
 Elliot

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Ticket URL: <https://core.trac.wordpress.org/ticket/41502#comment:5>
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