need help with form_set_value() error "warning: array_shift()...\form.inc"

You have not set #parents in $form['demo']['valid_test'], as mentioned in the documentation of form_set_value().
- Corey

I'm having the same problem. The API page differs from what's written in my Pro Drupal Development book, which doesn't say anything about #parents.

I've followed their example as closely as I can and I have the same problem you do.

If you figure it out please post the answer.

Thanks,

Nick

I ran into the same issue while working on a current project. After discussing said issue with CHX he relayed similar information as found in Drupal API documentation. Later I spoke with Merlinofchaos who gave the impression of a broken hook_validate. Merlin also provided me with a solution. So without further ado...

The Solution

If working with a node form you will want to create a custom validation function implemented by using hook_form_alter to add a custom #validate property.

<?php
function your_module_name_form_alter($form_id, &$form) {
  // Check to make sure that we only alter our form, unless of course you are
  // intending to alter all/several forms
  if ($form_id == 'your_node_form') {
  // your_new_validation is the name of your newly created validation function
    $form['#validate']['your_new_validate'] = array();
  }
}
?>

Define your custom validation function.

<?php
  function your_new_validate($form_id, $form_values, $form) {
    form_set_value($form['some_item'], $replacement_value);
  }
?>

While you could just define your custom validation function in _form the same way as we did in _form_alter, doing so would bypass the current node_validate function rendering any standard node validation useless and still wouldn't solve the error stated in this node. We don't usually want that so we use the hackish _form_alter so that both validation functions work as intended.

After completing this small task you can now use your modules custom validation function to perform the necessary changes and validation that you normally couldn't do including form_set_value. Now form_set_value should work properly and when you go on to your additional hooks like _submit, _insert, _update and perform a print_r($node) you should see the desired changes. And no more dirty error!

I hope this helps all the people I saw asking this very question. If this doesn't solve your problems with the related issue please lets get talking and I will do my best to help pass the solution in a well documented fashion.

Peace,
-mpare
www.paretech.com

Did you figure out how to do something? Did you find documentation on Drupal.org inadequate? Well now it's your turn. Document your Success!

I just fought with this problem myself while following along pg 163 in Pro Drupal Dev.

The solution is to ensure that your validate function has $form as the 3rd argument. ie:

formexample_nameform_validate($form_id, $form_values, $form) {
... //now form_set_value() will work
}

I'm losing my mind. I've read tons of posts on multistep forms and on altering data in the validate function.

The design:

* multistep form
* node content type created in CCK
* using form_alter to hide/add/alter fields
* use custom validate and submit functions

The problem:

* if there are no errors, the concept is fine (step from one step to next)
* if there are validation errors, I'm trying to figure out a way to *communicate* that fact to the form_alter function so that the *step* stays the same instead of incrementing
* I think I'm going to have trouble having a "back" button too (since I want to save first) - I will need to know I'm going backwards instead of forwards

I have tried:

1) in validate, set $_SESSION variable... this isn't available when needed (though if you submit again) it does show up

2) in form_alter, add a placeholder form field; and in the validate function, pass in the $form as 3rd param and use form_set_value for the placeholder... the placeholder is empty when I get back to the form_alter function after submitting

3) in form_alter, check the drupal_get_messages to see if anything is there (says it's empty even though there are messages)

Any ideas?????????? I'm about to give up on the whole thing and just build my form from scratch instead of doing form_alter but maybe I will have the same issue there.

Thanks,
Kristen

Let's say you want to update a value called wibble in anyform_form() where you created this field:

$form['wibble'] = array(
  '#type' => 'value',
  '#value' => array()
);

Now the problem is that every example you read tells you to use form_set_value() you have to have this in anyform_form:

// in hook_validate
form_set_value($form['wibble'], $my_data) ;

This is wrong. Even the book "Pro Drupal Development" says this and it's wrong. Some people use '#parents' to explain, but they never really explain, and this is why:

1) Your $form array is not available in hook_validate, so that's the first area of confusion. (And they always use $form.)

2) You do not use $form['wibble'] -- this is wrong and this is why it never works.

The people who mention '#parents' are on the right track. What you do with '#parents' is use it to identify where in the $form_values structure you want to put the value.

The first parameter for the example above can be created like this:

$x['#parents'] = array('wibble') ;

And then the second parameter is just the value you want to put in.

form_set_value($x,$myvalue) ;

And that will work.

Let's say you had something nested deep in the form_values (and used '#tree=true') and you'd do it like this:

$x['#parents']['level0']['level1']['level2'] = array('wibble') ;
form_set_value($x,$myvalue) ;

Obviously level0..2 above would be replaced by the actual names of the array elements. Notice that the name of the '#parents' array is completely irrelevant.

As a final note, you don't need to have created the field in '$form' at the top at all if you didn't want to -- the form_set_value() still works, but it's good practice to do it.

I hope that really helps.

Steve

This is what worked for me.

First in the hook_form make sure you define a value placeholder.

Example:

$form['timestamps_placeholder'] = array(
'#type' => 'value',
'#value' => 1 //1 is just a stub. It doesn't mean anything.
);

Secondly ensure that you are passing in the $form parameter in the hook_validate signature

function event_validate($node, $form) {
//Some Code
form_set_value($form['timestamps_placeholder'], $timestampArray);
}

It actually has 2 parameters as per http://api.drupal.org/api/function/hook_validate/6

Thirdly you have to actually insert the new value within the validate hook. e.g:

form_set_value($form['timestamps_placeholder'], $timestampArray);

Lastly you can now access the new value. You do it like:
$date_timestamps = $node->timestamps_placeholder;

-----------
Currently working on Starcraft 2 Center

Hey all - I also had issues with form_set_value in the validate hook (using Drupal 5). In my case I was doing this because I had a CCK content type with a field that I wanted to hide on the create / edit node form but fill in with a calculated value before save. For me the problem was I wasn't formatting the value I wanted to use for my form element in the Drupal Forms way. For example, if my CCK field is a textfield called 'calculated_data', then in the hook_form_alter I did:

// in hook_form_alter
// this is so the field doesn't show on the form
$form['field_calculated_data']['#type'] = 'value';
$form['field_calculated_data']['#value'] = array();

and

// in hook_validate - be sure you are using the hook_validate signature that has the $form as the third parameter...
// calculate the new value
$new_value = 'this is the new value';
// now put it in the format that Drupal expects
$field_value = array(array('value' => $new_value));
// finally update the form_values using form_set_value
form_set_value($form['field_calculated_data'], $field_value);

One other small note - the $form_values array will not have the updated value immediately after calling form_set_value, but it will be correct when the submit hook is called.

Hope this helps,

Dylan

If got here from a search engine looking for Drupal 6 info...
I've added a comment for Drupal 6's form_set_value documentation. http://api.drupal.org/api/function/form_set_value/6
I believe the problem most people have been having will be solved reading it.
Short version:

Use form_alter to add validate_custom to get: &$form_state.
Pass in 3 paramaters:

$first_parameter = array(
 '#parents' = array( // Important that the parents array contains $form_state's path keys
  'key_of_parent'
  ,'key_to_replace'
 );
);
$second_parameter = $value;
$third_parameter = $form_state;