CakePHP HABTM add/edit problems - cakephp

Question

I have the following relationship:
Edition:
public $hasAndBelongsToMany = array(
'Band' => array(
'className' => 'Band',
'joinTable' => 'bands_editions',
'foreignKey' => 'edition_id',
'associationForeignKey' => 'band_id',
'unique' => true,
)
);
Band:
public $hasAndBelongsToMany = array(
'Edition' => array(
'className' => 'Edition',
'joinTable' => 'bands_editions',
'foreignKey' => 'band_id',
'associationForeignKey' => 'edition_id',
'unique' => true,
)
);
BandsController:
public function add()
{
if($this->request->is('post'))
{
$this->Band->create();
if($this->Band->save($this->request->data))
doSomething();
else
doSomethingElse();
}
}
public function edit($id = NULL)
{
$this->Band->id = $id;
if(!$this->Band->exists())
throw new NotFoundException(__('Not found'));
if($this->request->is('post') || $this->request->is('put'))
{
if($this->Band->save($this->request->data))
doSomething();
else
doSomethingElse();
} else {
$this->request->data = $this->Band->read(NULL, $id);
}
}
When I try to populate Bands with add(), everything goes well, but as soon as I call edit(), Cake stops with this error:
Fatal error: Call to a member function schema() on a non-object
Debugging, I found that the error is fired when the parser reaches the check about the type of the request.
Which is my error?

Answer 1

Try this , I didn't see if it works
public function edit($id = null){
if(!$id){
throw new NotFoundException(__("Invalid Post"));
}
$band = $this->Band->findById($id);
if (!$band) {
throw new NotFoundException(__('Invalid Post'));
}
if ($this->request->is(array('post', 'put'))) {
$this->Band->id = $id;
if ($this->Band->save($this->request->data)) {
doSomething();
}
else {
doDomething();
}
}
if (!$this->request->data) {
$this->request->data = $Band;
}
}