What is the difference between the customer attribute properties user_defined and system and what are they used for?

Question

How to create a customer attribute is explained in various answers such as this or this. What they all have in common, is that when creating the attribute its properties user_defined and system are always defined like this:

'user_defined' => true,
'system' => false,

For me this doesn't work. When setting the properties as seen above the attribute is not visible in the adminhtml customer edit form. When setting user_defined => false and system => true it is shown but now saved. It only works (showing in form and saving) when both properties are set to false.

So my question is what is the difference between the two properties and what are they used for?

I am aware that these properties are used to mark "system attributes" which cannot be deleted easily like describes in this answer. I am looking for a more in depth answer what the difference between user_defined and system is. In addition what are both properties used for individually?

Answer 1

The user_defined property has already been explained, so let's have a look at system.

First, note that system is only used for customer and customer address attributes, while user_defined is a core property of all EAV attributes. They map to the following database tables and columns:

• user_defined => eav_attribute.is_user_defined
• system => customer_eav_attribute.is_system

I never paid much attention to system because it seems redundant, but looking at the code, it is only ever used in two occasions:

• customer system attributes (except password_hash) are not imported with the customer import, if they are also set to not visible, see \Magento\CustomerImportExport\Model\Import\Customer
• customer address system atttributes are not imported with the customer import, if they are also set to not visible, see \Magento\CustomerImportExport\Model\Import\Address

I can only guess why they don't use user_defined for the same purpose.

It is also interesting that the filter methods are implemented in the generic Magento_Eav model (see \Magento\Eav\Model\ResourceModel\Attribute\Collection::addSystemHiddenFilter() and \Magento\Eav\Model\ResourceModel\Attribute\Collection::addSystemHiddenFilterWithPasswordHash) although it obviously only is applicable to the customer attributes.

Answer 2

system > you cannot delete it this attribute from admin and it is created by magento core user_defined : you can delete it and generally when u create custom attribute it will be user_defined.