Problem with <backend_model>

Question

I'm getting a little desperate here with my custom Magento Backend Models.

Here is the situation: I have 2 multiselect (locales_served, countries_served) fields with custom backend models in my Magento Admin Configuration (as defined in system.xml below). They are mutually exclusive depending on another yes/no field.

So far, so good. Everything works fine as expected, the backend models work, too, BUT when I switch from one multiselect to the other, it uses the other options backend model. The backend classes are completely separate and I have no clue what's happening.

Let's say I start with locales_served, select some options and save - it works fine, my values are stored in the DB, all good. Then I go back to the Default Config, change to countries_served, select some options and save - BOOM, it overwrites my locales_served options.

<locales_served translate="label">
 <label>This Store serves these languages:</label>
 <frontend_type>multiselect</frontend_type>
 <backend_model>Foo_Bar_Model_LocaleMappingData</backend_model>
 <sort_order>5</sort_order>
 <source_model>adminhtml/system_config_source_locale</source_model>
 <show_in_default>0</show_in_default>
 <show_in_website>0</show_in_website>
 <show_in_store>1</show_in_store>
 <can_be_empty>1</can_be_empty>
 <depends><redirection_mode_select>locale</redirection_mode_select
 </depends>
</locales_served> 
<countries_served translate="label">
 <label>This Store serves these countries:</label>
 <frontend_type>multiselect</frontend_type
 <backend_model>Foo_Bar_Model_CountryMappingData</backend_model
 <sort_order>4</sort_order
 <source_model>adminhtml/system_config_source_country</source_model>
 <show_in_default>0</show_in_default>
 <show_in_website>0</show_in_website>
 <show_in_store>1</show_in_store>
 <can_be_empty>1</can_be_empty>
 <depends><redirection_mode_select>ip</redirection_mode_select>
 </depends>
</countries_served> 

Backend model class for locale select field:

class Foo_Bar_Model_LocaleMappingData extends Mage_Core_Model_Config_Data
{
const PATH = 'foo_bar/global_config/locales_served';
public function _afterSave()
{
 $h = Mage::helper('foo_bar/ConfigHelper'); 
 $storeId = $this->getScopeId();
 $h->updateMappings($storeId,$this->getValue(),self::PATH); 
}
}

backend model class for country select field, the echo produces this: 'foo_bar/global_config/locales_served' instead of 'foo_bar/global_config/countries_served'

class Foo_Bar_Model_CountryMappingData extends Mage_Core_Model_Config_Data
{
const PATH = 'foo_bar/global_config/countries_served';
public function _afterSave()
{
echo self::PATH;
exit;
 $h = Mage::helper('foo_bar/ConfigHelper'); 
 $storeId = $this->getScopeId();
 $h->updateMappings($storeId,$this->getValue(),self::PATH); 
}
}

Any ideas?

• Marius: can you add the updateMappings methods to the question?

Answer 1

What you describe is impossible if you don't add echo self::PATH to the other class as well. self::PATH gets replaced with the constant in the same class at compile time (other than static::PATH which would be replaced at runtime)

So the actual code that is executed must be something else. Possible reasons:

• uploaded files to the wrong server / wrong location
• Opcache contains an old version of the code

Answer 2

Figured it out - <depends>...</depends> just converts the select field into a hidden field if the condition is not met - the value is still posted though and my backend model is still instantiated.