Frequent CakePHP problems and solutions

On Google Groups you read about some problems over and over. So i thought, why not putting the most frequent ones together.

Add/Edit Post Url

If you have an url like "/products/add/import:1/manufacturer:4" and you want to preserve the url on POST, you will need this snippet:

echo $this->Form->create('Product', array('url'=>'/'.$this->params['url']['url']));

This way it will always post to the same url. The default behavior is to post to "/products/add" in this example above.

Adding user_id or other model related data on the fly

Some use hidden inputs for that. Very bad style! Never ever do that unless you have a damn good reason :). It can easily be manipulated (the security component will not help here at all!) and is absolute nonsense.
Just add it to the array before passing it to the model:

if (!empty($this->data)) { 
        $this->Product->create(); 
        $this->data['Product']['user_id'] = $this->Session- 
>read('Auth.User.id'); 

        if ($this->Product->save($this->data)) { 
                ... 
        } 
        ... 
}

Uploading Files

echo $this->Form->create('Model', array('type' => 'file'));
...
echo $this->Form->input('field', array('type' => 'file'));
...
echo $this->Form->end();

Both form and input need to be "file" in order to upload files.

Productive Server: "Error: Page not found"

If you just upload your files to your webserver, you might result in this error message. Although everything is supposed to work.
Make sure, that you erase all tmp files after you uploaded/modified files (especially if model-changes are involved). Otherwise it will try to work with the wrong files, which of course fails.

UTF8

Warning (2): htmlspecialchars(): Invalid multibyte sequence in argument in [/var/www/html/cake/basics.php, line 207]
I assume your application runs with utf8 as app encoding.

Usually this happens, if you forgot to save this file as utf8. It will then pass an invalid string to h(). In most cases it is a view (.ctp).
So make sure all views (and maybe even controllers for session flash messages and models for validation rules) that contain special chars are saved as utf8.
Tip: If you don’t know where it happens, use a stack trace to find the file causing this. Either manually by adding the stracktrace to the file_log.php or by using my cakephp addon "Proper logging feature".

Cannot modify header

Cannot modify header information - headers already sent by (output started at C:...\cake\cake\basics.php:305) [CORE\cake\libs\controller\controller.php, line 646]
This usually happens if you have ANY character printed out before the view actually renders. It can be a single space after the closing php tag of a php file (controller, model, …). Therefore you should not use ?> at the end of php files (CakePHP took the same path in summer 2010). It prevents this from happening.

Not found

It is very important to clear the "models" cache after manually changing anything on the database (tables). Also clear the "persistent" cache folder.
Otherwise it tries to use the old cached files which result in errors. With debug > 0 this is done automatically.

Ajax File Upload

You cannot upload files with AJAX itself. This will not work. Everything except for binary data.
There are workarounds, though. Jquery, for instance, uses hidden iframes.
So don’t use the ajax helper, but Jquery plugins or any other JS package to upload ajax files. Those usually use the above technique to workaround this problem.

Misc

… coming up