Why Magento2 set entity_type_id statically at CategorySetup, CustomerSetup

Question

I am trying to create a custom Eav entity in Magento 2.

I have gone through two core eav entity modules in Magento which are Catalog and Customer.

There are a couple of things which I found strange in these two modules.

Setup Files

• CategorySetup.php :

'entity_type_id' => self::CATEGORY_ENTITY_TYPE_ID

• CustomerSetup.php :

'entity_type_id' => \Magento\Customer\Api\CustomerMetadataInterface::ATTRIBUTE_SET_ID_CUSTOMER

It seems like Magento sets entity_type_id statically here.

Q1: Why Magento sets entity_type_id statically here though it manages dynamically within eav_entity_type table?

Q2: When are the records in eav_entity_type table created?

Q3: If I need to create a custom EAV model, the how should I define entity_type_id for that model

Answer 1

This is a partial answer. And logically deduced therefor prone to error.

The eav_entity_table is populated at Magento installation. The only way to change existing values in the table si by custom added logic.

They are making the assumption that no one(in their right mind) changes those values. Ergo they extracted the values into constants making the following assumption

No Magento installation will mess with native entity_type_ids of core Magento entities.

The reason is simple to deduce: performance;

You are right in saying that you should treat your custom entity_type_id as a dynamic value because there are other extensions that might have added their own custom-entities so there is no guarantee that 9 will always represent your custom entity for example.