Create Magento Backend Field ReadOnly - magento

Question

I would like to create a read-only field in the backend at the client's Magento.
create fields to know (through a module) is as follows:
$installer->addAttribute("customer", "attrcode", array(
"type" => "varchar",
"backend" => "",
"label" => "label",
"input" => "text",
"source" => "",
"visible" => true,
"required" => false,
"default" => "",
"frontend" => "",
"unique" => false,
));
this way it creates the field, but he's not just reading ...
Thank You

Answer 1

One possible solution is to use javascript to disable the button on page load
Create a js file and upload it to your admin skin/js directory (disable_button.js)
add
document.observe('dom:loaded', function(){
$("target_input_id").disabled=true;
});
Then add or update you local.xml to include the js files
<?xml version="1.0"?>
<layout version="0.1.0">
<adminhtml_customer_edit>
<reference name="head">
<action method="addItem"><type>skin_js</type><script>js/disable_button.js</script></action>
</reference>
</adminhtml_customer_edit>
</layout>

Answer 2

I don't think what you are trying to is possible using addAttribute(), _prepareValues($attr) method only allow specific values that are store in $data.
Take a look # app/code/core/Mage/Eav/Model/Entity/Setup.php
public function addAttribute($entityTypeId, $code, array $attr)
{
$entityTypeId = $this->getEntityTypeId($entityTypeId);
$data = array_merge(
array(
'entity_type_id' => $entityTypeId,
'attribute_code' => $code
),
$this->_prepareValues($attr);
);
.....
if ($attributeId) {
$this->updateAttribute($entityTypeId, $attributeId, $data, null, $sortOrder);
} else {
$this->_insertAttribute($data);
}
.......
}
protected function _prepareValues($attr)
{
$data = array(
'backend_model' => $this->_getValue($attr, 'backend'),
'backend_type' => $this->_getValue($attr, 'type', 'varchar'),
'backend_table' => $this->_getValue($attr, 'table'),
'frontend_model' => $this->_getValue($attr, 'frontend'),
'frontend_input' => $this->_getValue($attr, 'input', 'text'),
'frontend_label' => $this->_getValue($attr, 'label'),
'frontend_class' => $this->_getValue($attr, 'frontend_class'),
'source_model' => $this->_getValue($attr, 'source'),
'is_required' => $this->_getValue($attr, 'required', 1),
'is_user_defined' => $this->_getValue($attr, 'user_defined', 0),
'default_value' => $this->_getValue($attr, 'default'),
'is_unique' => $this->_getValue($attr, 'unique', 0),
'note' => $this->_getValue($attr, 'note'),
'is_global' => $this->_getValue($attr, 'global',
Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL
),
);
return $data;
}

Answer 3

I have developed exactly such extension that work for products, categories and CMS pages. You just have to define some rules and choose which attributes you want to show as read-only.
Extension URL: https://www.bubbleshop.net/magento-admin-readonly.html