Magento Changing Default Payment Method - magento

Question

I have a function that runs raw SQL queries to our database in Magento. What the function does is changes the customer's default credit card to a value passed to the function. My question is how would I rewrite the function utilizing Magento models. The current function works, but we'd rather have it not be directly interfacing with SQL.
Here is the function:
public function setDefaultPayment($value)
{
$customerId = $this->_getSession()->getCustomer()->getId();
$write = Mage::getSingleton('core/resource')->getConnection('core_write');
$read = $write->query("SELECT entity_type_id FROM eav_entity_type WHERE entity_type_code='customer'");
$row = $read->fetch();
$entity_type_id = $row['entity_type_id'];
$read = $write->query("SELECT attribute_id FROM eav_attribute WHERE attribute_code='default_payment' AND entity_type_id = $entity_type_id");
$row = $read->fetch();
$attribute_id = $row['attribute_id'];
$read = $write->query("SELECT * FROM customer_entity_int WHERE entity_type_id='$entity_type_id' AND attribute_id='$attribute_id' AND entity_id='$customerId'");
if ($row = $read->fetch()) {
$write->update(
'customer_entity_int',
array('value' => $value),
"entity_type_id='$entity_type_id' AND attribute_id='$attribute_id' AND entity_id='$customerId'"
);
} else {
$write->insert(
'customer_entity_int',
array(
'entity_type_id' => $entity_type_id,
'attribute_id' => $attribute_id,
'entity_id' => $customerId,
'value' => $value
)
);
}
}

Answer 1

If I read you code right, you want to update the customer attribute default_payment with a value given.
For that you need to:
Load the customer by id
Set the new value for the customer attribute default_payment
Save the customer
public function setDefaultPayment($value)
{
$customerId = $this->_getSession()->getCustomer()->getId();
$write = Mage::getSingleton('core/resource')->getConnection('core_write');
$customer = Mage::getModel('customer/customer')->load($customerId);
$oldValue = $customer->getDefaultPayment(); // optional, just for checking
$customer->setDefaultPayment($value);
$customer->save();
}