CakePHP：FormHelper没有显示关联模型的默认值

We have two models which are related by a has and belongs to many (HABTM) relationship: Jobs, Tests. We are able to add/edit the relationships successfully (we know because they show up in the join table), but we can't get the existing values to appear in the view. The select/checkboxes (we've tried both) are always empty.

Here are the model relationships:

//Job.php
public $hasAndBelongsToMany = array (
    'Test' => array (
        'classname' => 'Test', 
        'foreignKey'=>'job_id',
        'joinTable' => 'jobs_tests',
        'associatedForeignKey' => 'test_id'
    )
);

//Test.php
    public $hasAndBelongsToMany = array(
        'Job' => array(
            'className'=> 'Job',
            'joinTable'=>'jobs_tests',
            'foreignKey' => 'test_id',
            'associatedForeignKey'=> 'job_id'
            )

    );

Here is the /view/Jobs/edit.ctp

            echo $this->Form->select('Test', $test_options, array('class'=>'form-control', 'multiple'=>'checkbox'));
//This is always empty (nothing selected/checked). 

What are we doing wrong?

Update:

Here is the JobsController action:

public function admin_edit( $id=NULL ) {
    $this->layout = 'admin';
    if (!$id)
        $this->redirect( array('controller'=>'jobs', 'action'=>'index'));

    $this->loadModel('Company');
    $companies = $this->Company->find('all');
    $company_options = array();
    foreach ($companies as $company) {
        $company_options[ $company['Company']['id'] ] = $company['Company']['name'];
    }
    $this->set('company_options', $company_options);

    $this->loadModel('Test');
    $tests = $this->Test->find('all');
    $tests_options = array();
    foreach ($tests as $test) {
        $test_options[ $test['Test']['id'] ] = $test['Test']['name'];
    }
    $this->set('test_options', $test_options);

    $category_options = $this->Job->validCategories;

    $this->set('category_options', $category_options);

    if ($this->request->isPut() ) {
        $data = $this->request->data;
        //debug($data);exit;
        $save = $this->Job->save( $data );
        if ($save) {
            $this->Session->setFlash('Job edited');
            //$job = $this->Job->findById( $id );
        } else {
            $this->Session->setFlash('Error editting job');
        }


    } 

    $job = $this->Job->findById($id);
    $this->request->data = $job;
    $this->set('job', $job);
}

Here is the form in the admin_edit.ctp view:

<?php echo $this->Form->create('Job'); ?>
    <fieldset>
        <?php
            echo $this->Form->input('id', array('type'=>'hidden'));
            echo $this->Form->input('name', array('class'=>'form-control')); 
            echo $this->Form->input('email', array('class'=>'form-control'));
            echo $this->Form->input('location', array('class'=>'form-control'));

            echo '<label>Type</label>';
            echo $this->Form->select('type', array('FT'=>'Full Time', 'PT'=>'Part Time', 'IN'=>'Internship'), array('empty'=>false, 'class'=>'form-control'));

            echo '<label>Company</label>';
            echo $this->Form->select('company_id', $company_options, array('class'=>'form-control')); 
            echo $this->Form->input('short_description', array('label' => 'Short Description', 'class'=>'form-control'));
            echo $this->Form->input('full_description', array('type'=>'textarea', 'label' => 'Full Description', 'class'=>'form-control'));
            echo $this->Form->input('is_private', array('label'=>'Is Private?', 'class'=>'form-control') );

            echo '<label>Category</label>';
            echo $this->Form->select('category', $category_options, array('class'=>'form-control'));
            echo '<label>Tests</label>';            
            //echo $this->Form->select('Test.id', $test_options, array('class'=>'form-control', 'multiple'=>true));

            $selected = array();
            foreach ($job['Test'] as $test) {
                $selected[]=$test['id'];
                //$selected[ $test['id'] ] = $test['name'];
            }
            debug($selected);
            echo $this->Form->input('Test', array('type'=>'select', 'options'=>$test_options, 'class'=>'form-control', 'multiple'=>'checkbox', 'selected'=>$selected));
        ?>
    </fieldset>
    <?php echo $this->Form->end(__('Submit')); ?>

PHEW! This was a stumper but the solution turned out to be simple... The values in $options['selected'] were strings (of numbers), which was confusing CakePHP. We converted them to ints using intval() and it works perfectly now, using all the original settings...

Here's the revised version of what is in the view (notice the intval()):

        $selected = array();
        foreach ($job['Test'] as $test) {
            $selected[]= intval($test['id']);
        }
         echo $this->Form->input('Test', array('type'=>'select', 'options'=>$test_options, 'class'=>'form-control', 'multiple'=>'checkbox', 'selected'=>$selected));

Also, as a sidenote, this is evidence that pretty much everything that was challenged in the comments above works completely fine:

1. $options['selected'] does not need to be key=>value pairs.
2. The pattern we're using does not overwrite the request->data and passes the data to the form helper just fine.
3. non-camelCased variable names passed to the view ($some_variable_name) are still picked up correctly by the form helper.

Hopefully this comes in handy to someone else.

What if you pass set the default values using Model::find('list').

//controller
$this->set('test_options', $this->YourModel->find('list'));


//view
 echo $this->Form->select('Test', $test_options, array('class'=>'form-control', 'multiple'=>'checkbox'));