How to Upload Pdf Name Change in Drupal 7

Form validation is an essential office of whatever web system. You demand to ensure that the user has added valid data and if non, show them a meaningful error message. Validation functions are commonly implemented in the module where the class is defined. However, thanks to Drupal'due south hook system, you tin add a validation function to whatsoever Drupal class, even if you lot did non create the form. In this tutorial, you volition acquire how to add together a validation office to the node commodity class. This is the form where you add content to the commodity content type and can be institute here: node/add/article

Imagine you lot want to ensure users cannot add together the following championship: "the quick play a joke on jumped over the lazy domestic dog". If they practice, they should receive an mistake message and the title field should be highlighted to ensure they know which field has an invalid value.

For this tutorial, you volition demand to download and enable a module chosen devel so that you lot can use its Drupal Print Message (dpm) role.

Modify the class

To add together the new validation function, you need to alter the form. Y'all can do this by implementing hook_form_alter(). We covered this in Day 7 of Starting Drupal Module Development. You volition need a custom module to implement hook_form_alter. In the instance below, I am using the module created in Day 3 of Starting Drupal Module Development. If you have not signed up for it, yous can practise so hither.

In our implementation of hook_form_alter, we will take a expect at the validation functions already set for the article node class.

            role starting_drupal_dev_form_alter(&$form, &$form_state, $form_id) {   if ($form_id == 'article_node_form') {     dpm($form['#validate']);   } }                      

In the above code, we are first checking that the form id is article_node_form. And and then, we are calling dpm($form['#validate']), which volition evidence u.s. an array of the validation functions. $form['#validate'] is a form element which lists all of the validation functions for a given class.

When you hit node/add/article, you will run into node_form_validate(), which is the cadre validator for node forms.


Add a validation handler to the grade

You demand to add your validation office to that array by adding the following: $class['#validate'][] = 'starting_drupal_dev_form_validate'. $form['validate'] is an array and you lot can add to that with $grade['#validate'][].

            role starting_drupal_dev_form_alter(&$form, &$form_state, $form_id) {   if ($form_id == 'article_node_form') {     $class['#validate'][] = 'starting_drupal_dev_form_validate';     dpm($grade['#validate']);   } }                      

Y'all will see at that place are now two validation handlers, the cadre node_form_validate and the one that you added, starting_drupal_dev_form_validate.

Create the validation role

Now you need to add a role called starting_drupal_dev_form_validate().

            office starting_drupal_dev_form_validate($grade, &$form_state) {  }                      

When the form is submitted, the grade values will be held in $form_state. To encounter what is included in form_state(), add together dpm($form_state); to the validation function.

            office starting_drupal_dev_form_validate($form, &$form_state) {   dpm($form_state); }                      

Yous will and then come across an array with data from the form you just submitted. We are interested in the values that the user adds to the form, which is held in $form_state['values'].

In the validation office, you need to check the value of the title field, which is held in $form_state['values']['title']. If the value is "the quick fox jumped over the lazy canis familiaris" then set an error.

            function starting_drupal_dev_form_validate($class, &$form_state) {   if ($form_state['values']['championship'] == 'the quick fox jumped over the lazy dog') {     form_set_error('title', t('You have added an invalid title.'));   } }                      

Let's pause down the to a higher place function.

            if ($form_state['values']['title'] == 'blackness') { … }                      

This is a uncomplicated PHP if statement. If the value of the title field is 'the quick fob jumped over the lazy domestic dog', it will be true and the code inside the if statement will exist executed.

            form_set_error('title', t('You are not allowed to use "the quick flim-flam jumped over the lazy dog" every bit a title.'));                      

The Drupal office form_set_error() is called. The first parameter is the name of the field that has acquired the error. In our instance, this is the title field. The field specified will be highlighted with a cerise border, and then the user has a clear visual cue as to which field has not validated. The second parameter is the fault message, which volition be displayed in the bulletin area of the page.

Brand multiple titles invalid

Now let'south have this ane pace further. Let'due south brand two phrases invalid, rather than just one. The second invalid title is "birds of a plume flock together".

To do that, the validation role will get:

            function starting_drupal_dev_form_validate($form, &$form_state) {   $invalid_titles = array('the quick fox jumped over the lazy dog', 'birds of a feather flock together');   if (in_array($form_state['values']['title'], $invalid_titles)) {     form_set_error('title', t('You have added an invalid title.'));   } }                      

Let's break this downwards.

            $invalid_titles = array('the quick fox jumped over the lazy domestic dog', 'birds of a feather flock together');                      

First, we take created an array of invalid titles.

                          if (in_array($form_state['values']['title'], $invalid_titles)) { .. }                      

Then we check if the championship that the user has added is in that array using PHP'due south in_array part. If it is, the if statement will return truthful and the form_set_error will be set. You lot tin can add together as many invalid titles every bit yous similar to the $invalid_titles array.

And that is all there is to it. There is much more yous tin can do with validation handlers, which we will become into in later tutorials.

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Source: https://befused.com/drupal/form-validation/

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