Invalid argument supplied for foreach() when asking confirmation to enable required modules

Can you give us any kind of information how to reproduce the problem?

One thing that would might help is to write dvm(views_trace()) in element_children with a if() wrapped.
So you could find out which function calls this.

function element_children(&$elements, $sort = FALSE) {
  // Do not attempt to sort elements which have already been sorted.
  $sort = isset($elements['#sorted']) ? !$elements['#sorted'] : $sort;

  // Filter out properties from the element, leaving only children.
  $children = array();
  $sortable = FALSE;
  foreach ($elements as $key => $value) {

Should be

function element_children(&$elements, $sort = FALSE) {
  // Do not attempt to sort elements which have already been sorted.
  $sort = isset($elements['#sorted']) ? !$elements['#sorted'] : $sort;

  // Filter out properties from the element, leaving only children.
  $children = array();
  $sortable = FALSE;
  if (!is_array($elements) && function_exists('views_trace')) {
    dsm(views_trace());
  }
  foreach ($elements as $key => $value) {

You need devel module installed for this.

Oh interesting.
It's really important that you give more context on your issues.
Take sure you try out to reproduce this bug on a clean drupal installation. The error could be caused by many other things.

There's too many modules involved. I doubt someone else will be interested in digging through them all to find out which one causes the problem. You need to reduce the number of involved modules as much as possible, which will most likely be 1. And even then there's a major risk you'll be asked to file an issue with that module instead of Views.

This error occurs with other modules also.

I get this error when I enable a module that is dependent on another module that isn't enabled.

That error appears just before the the message...

You must enable the ***missing*** modules to install ***this-module***. (***fill in the blank***)
Would you like to continue with the above?
continue cancel

I haven't noticed any affect on the function of the installed modules after clicking continue and the installation completes.

There may be other instances where this occurs. I know I can duplicate it every time by enabling modules with dependencies.

So this might be a core issue, and it might not. With the information available at the moment, there is nothing we can do, and regardless, it's questionable at best whether or not this is Views related.

I guess it's not views related at all. I run just into it. Fres D7 install, I started with minimal profile. Enabled some more modules but not yet Views. I didn't pay attention when the warning appeared the first time but now I have attached a debugger and I see that the following stack trace

Remote Launch (suspended)	
	D7-dropbox/includes/common.inc.element_children : lineno 6046() D7-dropbox/includes/common.inc at line 6046	
	D7-dropbox/sites/all/modules/advanced_help/advanced_help.module.advanced_help_form_system_modules_alter : lineno 322() D7-dropbox/sites/all/modules/advanced_help/advanced_help.module at line 322	
	D7-dropbox/includes/module.inc.drupal_alter : lineno 1002() D7-dropbox/includes/module.inc at line 1002	
	D7-dropbox/includes/form.inc.drupal_prepare_form : lineno 1038() D7-dropbox/includes/form.inc at line 1038	
	D7-dropbox/includes/form.inc.drupal_rebuild_form : lineno 451() D7-dropbox/includes/form.inc at line 451	
	D7-dropbox/includes/form.inc.drupal_process_form : lineno 900() D7-dropbox/includes/form.inc at line 900	
	D7-dropbox/includes/form.inc.drupal_build_form : lineno 350() D7-dropbox/includes/form.inc at line 350	
	D7-dropbox/includes/form.inc.drupal_get_form : lineno 188() D7-dropbox/includes/form.inc at line 188	
	D7-dropbox/includes/menu.inc.call_user_func_array : lineno 501() D7-dropbox/includes/menu.inc at line 501	
	D7-dropbox/includes/menu.inc.menu_execute_active_handler : lineno 501() D7-dropbox/includes/menu.inc at line 501	
	D7-dropbox/index.php.{main} : lineno 22() D7-dropbox/index.php at line 22	

the advanced_help.module.advanced_help_form_system_modules_alter sends a $form['modules'] to common.inc.element_children() which is undefined

move to Advanced Help?

Yes, move to advanced help.

Thanks! for provide a backtrace. This is great!!

This patch checks the $form['modules'] variable is set before sending to common.inc > element_children().

In function advanced_help_form_system_modules_alter(&$form, &$form_state)
$form['modules'] can be undefined.

What solves this problem for me is a simple check before executing the outer loop:
if (isset ($form['modules'])) {
foreach...
}

Problem occurs when the modules list form gets back to ask permission to enable required modules. in that case there is no list of modules on the form. So the patch is the correct solution and works for me.

Only remark could be to also test if $form['modules'] is an array if it is set, but the context will probably ensure that it is either not set or it is an array.

I can confirm this bug, and the patch is ok

Yes, the analysis is correct (empty form['modules'] on "Some required modules must be enabled" confirmation page) and the patch does work. But imho it's a little cleverer to exit the function straight away, also that way the indentation depth doesn't increase further -> no whitespace diff...

That's a matter of style and personal preference. Personally, I prefer the "1 exit point only" coding style (#14), but I don't care that much. e.g., if in the future you would want to alter another part of the form, you will have to revert to the way #14 does it anyway.

However, #18 is functionally equivalent to #14, so pick one and please commit it.

@fietserwin: well the difference it makes is

• smaller diff :)
• one less function call because it aborts earlier

but your point's valid too so..

Good catch. That function call should be in the if as well ... Reroll of #14. Please make your choice between #18 and #21 ...

Because it's so darn close to the line #nr i'll try it here first:

Warning: Invalid argument supplied for foreach() in element_children() (line 6161 of [path]/includes/common.inc).

That's on D7.10, Advanced Help 7.x-1.0 and Advanced Help 7.x-1.x-dev 25 feb. 2011. (also have backup migrate installed, but that's really all)

I get the error when i try to install Pathauto 7.x-1.0 if i don't select token, it shows up on the confirmation page. If it's not related i'll dive into it if time permits and roll a separate issue, but first let's try here.

(so, clean install of drupal + contact, content translation, trigger, tracker core modules + backup migrate and advanced help Installed, then select pathauto and hit install)

- Clarified title.
- #22: Probably the same, common.inc has been changed since the original report.
- Can someone else RTBC (latest patch is mine)?

This works fine, thanks a lot.

I keep getting 6161 error on common.inc. I debugged this with some help and it was traced back to advanced help. The error used to pop up when a module was being installed. I'd click save and carry on and everything appears to be working fine. It got very annoying having to deal with this everytime a mod was enabled.

Since i've stopped using the module the error no longer pops up. I'd really like to be using the mod. Is there any plans to fix this?

I'd be willing to provide any info necessary. I was using 7.10 now i'm using 7.12 - and have not installed the mod with that yet.

Thanks

I'm getting different 6xxx thousand errors all to do with common.inc.element_children() when installing other modules.

Does the patches on #18 + #21 fix these error notices? If so could a new patched version of advanced help be released?

This may be related: #1711256: Enabling disabled modules causes error: Invalid argument supplied to element_children()

Works.

Thanks all! It's been moved into 7.x-1.x-dev.