取消选中cakephp中的值

I have following checkbox

<td><?php echo  $this->Form->checkbox('purchase_owner_occupied', array('hiddenField' => false));?>Purchase owner occupied </td>
<td><?php echo  $this->Form->checkbox('purchase_an_investment_property', array('hiddenField' => false));?>Purchase an investment property </td>
<td><?php echo  $this->Form->checkbox('purchase_land', array('hiddenField' => false));?>Purchase Land </td>

When I check then then the post value is like below

[purchase_owner_occupied] => 1 
[purchase_an_investment_property] => 1 
[purchase_land] => 1 

Let say I need to edit those information to uncheck purchase_land, when I uncheck purchage_land and check remaining 2 the post value will be as below

[purchase_owner_occupied] => 1 
[purchase_an_investment_property] => 1 

I need to check all these value with extrastep code

if ($purchase_owner_occupied==1)  { // }

Isn't there are way so that unchecked field will have 0 value like below?

[purchase_owner_occupied] => 1 
[purchase_an_investment_property] => 1 
[purchase_land] => 0

You need to use different values ​​of 0/1 and also the hiddenField parameter is required:

<td><?php echo  $this->Form->checkbox('purchase_owner_occupied', array('value' => 'y', 'hiddenField' => 'n')); ?>Purchase owner occupied</td>
<td><?php echo  $this->Form->checkbox('purchase_an_investment_property', array('value' => 'y', 'hiddenField' => 'n')); ?>Purchase an investment property</td>
<td><?php echo  $this->Form->checkbox('purchase_land', array('value' => 'y', 'hiddenField' => 'n')); ?>Purchase Land</td>

Example output if I just select the second checkbox:

array(
        'purchase_owner_occupied' => 'n',
        'purchase_an_investment_property' => 'y',
        'purchase_land' => 'n'
    )