How Can I Check The Changes For The Fields At Form Alter Submit?

Apr 19, 2025 by ADMIN 65 views

**How can I check the changes for the fields at form alter submit?**

Introduction

When working with forms in Drupal, it's often necessary to check for changes in the form fields after the user submits the form. This can be particularly useful when you want to perform custom actions based on the changes made to the form fields. In this article, we'll explore how to check for changes in the form fields at form alter submit using the hook_form_alter() function with a custom submit handler.

Understanding the Problem

When you use the hook_form_alter() function to modify a form, you can add a custom submit handler to perform actions after the form is submitted. However, when you want to check for changes in the form fields, you need to access the form state and compare the current values with the original values. This can be a bit tricky, especially when you're dealing with complex forms.

Accessing the Form State

To access the form state, you need to use the $form_state variable, which is an array that contains information about the form, including the current values of the form fields. To check for changes in the form fields, you need to compare the current values with the original values.

Comparing Current and Original Values

To compare the current and original values, you can use the form_get_values() function, which returns an array of the current values of the form fields. You can then compare this array with the original values stored in the $form_state array.

Example Code

Here's an example code snippet that demonstrates how to check for changes in the form fields at form alter submit:

function mymodule_form_alter(&$form, &$form_state, $form_id) {
  // Add a custom submit handler to the form
  $form['#submit'][] = 'mymodule_submit_form';
}
function mymodule_submit_form( $form, &amp;$ form_state) {
// Get the current values of the form fields
 $current_values = form_get_values($ form, $form_state);
// Get the original values of the form fields
$original_values = $form_state['values'];
// Compare the current and original values
foreach ($current_values as $key =>  $value) { if ($ value !==  $original_values[$ key]) {
// Perform custom actions based on the changes
// For example, you can log the changes or send an email
drupal_set_message('Change detected in field ' . $key);
}
}
}

Checking for Changes Except Node->Expire

However, in your case, you want to check for changes in the form fields except for the node->expire field. To do this, you can modify the code snippet above to exclude the node->expire field from the comparison:

function mymodule_submit_form($form, &$form_state) {
  // Get the current values of the form fields
  $current_values = form_get_values($form, $form_state);
// Get the original values of the form fields
$original_values = $form_state['values'];
// Exclude the node->expire field from the comparison
unset( $current_values[&#39;node&#39;][&#39;expire unset($ original_values['node']['expire']);
// Compare the current and original values
foreach ($current_values as $key =>  $value) { if ($ value !==  $original_values[$ key]) {
// Perform custom actions based on the changes
// For example, you can log the changes or send an email
drupal_set_message('Change detected in field ' . $key);
}
}
}

Conclusion

In this article, we've explored how to check for changes in the form fields at form alter submit using the hook_form_alter() function with a custom submit handler. We've also demonstrated how to exclude the node->expire field from the comparison. By following the code snippets above, you can perform custom actions based on the changes made to the form fields.

Additional Tips and Variations

To check for changes in specific form fields, you can use the $form_state['values'] array to access the current values of the form fields.
To perform custom actions based on the changes, you can use the drupal_set_message() function to display a message or send an email using the drupal_mail() function.
To exclude multiple form fields from the comparison, you can use the unset() function to remove the fields from the $current_values and $original_values arrays.

Q: What is the purpose of the `hook_form_alter()` function?

A: The hook_form_alter() function is a hook in Drupal that allows you to modify the form structure and behavior. It is called after the form has been built, but before it is rendered.

Q: How do I add a custom submit handler to a form using `hook_form_alter()`?

A: To add a custom submit handler to a form using hook_form_alter(), you need to add the custom submit handler to the $form['#submit'] array. For example:

function mymodule_form_alter(&$form, &$form_state, $form_id) {
  // Add a custom submit handler to the form
  $form['#submit'][] = 'mymodule_submit_form';
}

Q: How do I access the form state in a custom submit handler?

A: To access the form state in a custom submit handler, you need to use the $form_state variable. This variable is an array that contains information about the form, including the current values of the form fields.

Q: How do I compare the current and original values of the form fields?

A: To compare the current and original values of the form fields, you can use the form_get_values() function to get the current values of the form fields, and then compare them with the original values stored in the $form_state array.

Q: How do I exclude the `node->expire` field from the comparison?

A: To exclude the node->expire field from the comparison, you can use the unset() function to remove the field from the $current_values and $original_values arrays.

Q: What is the purpose of the `drupal_set_message()` function?

A: The drupal_set_message() function is used to display a message to the user. It can be used to display a message after a form has been submitted, or to display an error message if something goes wrong.

Q: How do I send an email using the `drupal_mail()` function?

A: To send an email using the drupal_mail() function, you need to call the function and pass in the email address, subject, and message. For example:

drupal_mail('mymodule', 'mymodule_email', 'user@example.com', language_default(), array('message' => 'Hello, world!'));

Q: What are some common use cases for checking changes in form fields?

A: Some common use cases for checking changes in form fields include:

Validating user input
Sending notifications when a form is submitted
Updating a database table when a form is submitted
Displaying a message to the user when a form is submitted

Q: How do I debug my custom submit handler?

A: To debug your custom submit handler, you can use the drupal_set_message() function to display a message after the form has been submitted. You can also use dpm() function to display the values of variables in the form state.

Q: What are some best practices for writing custom submit handlers?

A: Some best practices for writing custom submit handlers include:

Using the hook_form_alter() function to add custom submit handlers
Using the $form_state variable to access the form state
Comparing the current and original values of the form fields
Using the drupal_set_message() function to display messages to the user
Using the drupal_mail() function to send emails
Validating user input
Updating a database table when a form is submitted