Re: Adding new items to a form dynamically

The reason is Cakes security layer, when creating forms with the Form
helper, it automatically creates a signature based on the form
elements (position, type, id, name, etc). When receiving data Cake
checks the signature (data[_Token][key] and data[_Token][fields])
against the value stored in the session, and if it doesn't match the
request gets blackholed, see:

http://book.cakephp.org/view/1296/Security-Component

So when using the security component, you must "resign" your forms,
that's a bit tricky because there's no interface that simply gives you
these values, you have to create the form, and then fetch the values
from the genereated HTML, that can for example be done using regular
expressions or the XML parser.

What i do in such cases is sending an AJAX request with the number of
elements (in this case file input fields), generate the form and store
the newly created elements in an array, and fetch the token values
using XML and Set. After receiving the data i do udpate the form by
adding the newly genereated elements and updating the token elements.

I have recently done it in a project, this is how i regenerate the
form and fetch the field and token data:

http://pastebin.com/WAKD5X2P

It creates a form with where the first div contains the _Token.key
input field, and the last one the _Token.fields one. The genereated
fieldsets contain the file input elements. The JavaScript part looks
something like this, it simply updates the _Token input fields and
appends the newly generated form elements if neccessary:

http://pastebin.com/d9tYQUT3

Regards

Arak Tai'Roth schrieb:
> So, here is my situation. I have a form that allows users (only
> admins) to upload images for a specific product. What I have created
> is a solution that when they load the add form initially it has one
> file upload and one caption text box. However, they can click a button
> lower down, that dynamically adds another file upload and another
> caption box, so they can essentially upload however many images they
> want to at a time.
>
> Here is the code that I have:
>
> images_controller.php
> function add($productID = NULL)
> {
> if ($this->RequestHandler->isPost())
> {
> $slug = $this->Session->read('ProductSlug');
>
> if ($this->Image->saveAll($this->data))
> {
> $this->Session->setFlash('Images have been added to the product.');
>
> $this->redirect('/product/' . $slug);
> $this->exit();
> }
> }
> else
> {
> $this->Session->write('ProductID', $productID);
> $this->Session->write('ImageCounter', 0);
> }
> }
>
> function moreImages()
> {
> if ($this->RequestHandler->isAjax())
> {
> $images = $this->Session->read('ImageCounter');
> $images++;
> $this->Session->write('ImageCounter', $images);
>
> $this->render('/elements/imageAdd');
> }
> }
>
> and imageAdd.ctp
> $image = $this->Session->read('ImageCounter');
>
> echo $this->Form->input('Image.' . $image . '.product_id',
> array('type' => 'hidden', 'default' => $this->Session-
> >read('ProductID')));
>
> echo $this->Form->label('Image.' . $image . '.filename', 'Image:');
> echo $this->Form->input('Image.' . $image . '.filename',
> array('label' => false, 'type' => 'file'));
>
> echo $this->Form->label('Image.' . $image . '.caption', 'Caption:');
> echo $this->Form->input('Image.' . $image . '.caption', array('label'
> => false));
>
> and finally the js file that adds the stuff:
> $(document).ready(function() {
> $('#forms img').click(function() {
> $.ajax({
> url: someUrl',
> dataType: 'html',
> success: function(data) {
> $('#forms div.formInputs').append(data);
> }
> });
> });
> });
>
> Now, what this does. When the user goes to the add form, it renders
> the element imageAdd. Which creates 3 form elements, 1 hidden. Each
> form element is rendered with Image.0.columnName. Then if they click
> the image at the bottom, it renders another element imageAdd, but this
> time the elements are all named Image.1.columnName, and so on.
>
> Now for my issue. All of this works fine if they just add one image.
> However, that clearly defeats the purpose of this. When they go to add
> 2 or more images, it goes to a blank screen, where even the view
> source is blank. So I have no idea what's going wrong. It goes there
> before the timeout that's declared in php.ini, and I've made sure that
> the combined filesize is also lower then what's allowed in my php.ini.
>
> Also, if it makes a difference, I am using MeioUpload for the file
> upload behaviour. Any help on this is greatly appreciated.

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