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Creating Objects

When first creating an object, it will have a resource named 0x1::object::ObjectCore added. This contains metadata about the object, as well as information about the owner of the object.

Objects can be created in multiple ways depending on your needs. They can be broken into two main types of objects:

  • Deletable objects
  • Non-deletable objects

Creating a deletable object​

Generally, users want objects to be deletable. If an object is deletable, then storage refunds can be acquired by deleting the object, saving on gas.

Deletable Objects​

Create object generates a random unique address based on the transaction hash and a counter. The addresses of the objects are always unique and this is the preferred way to make most objects.

module my_addr::object_playground {
  use std::signer;
  use aptos_framework::object;

  entry fun create_my_object(caller: &signer) {
    let caller_address = signer::address_of(caller);
    let constructor_ref = object::create_object(caller_address);
    // ...
  }
}

Creating a non-deletable object​

Non-deletable objects are useful for certain situations that need a guarantee of an existing object. There are two ways to handle this on Aptos:

  • Named objects
  • Sticky objects

Named objects​

Create named object lets you create an object with a fixed seed. This makes it easy to later

module my_addr::object_playground {
  use std::signer;
  use aptos_framework::object;

  /// Seed for my named object, must be globally unique to the creating account
  const NAME: vector<u8> = b"MyAwesomeObject";

  entry fun create_my_object(caller: &signer) {
    let caller_address = signer::address_of(caller);
    let constructor_ref = object::create_named_object(caller_address, NAME);
    // ...
  }

  #[view]
  fun has_object(creator: address): bool {
    let object_address = object::create_object_address(&creator, NAME);
    object_exists<0x1::object::ObjectCore>(object_address)
  }
}

Sticky objects​

This is exactly the same as deletable objects, but the object cannot be deleted. This is necessary for uses like fungible asset metadata that would want to not be deleted.

module my_addr::object_playground {
  use std::signer;
  use aptos_framework::object;

  entry fun create_my_object(caller: &signer) {
    let caller_address = signer::address_of(caller);
    let constructor_ref = object::create_sticky_object(caller_address);
    // ...
  }
}