Using CollectionSetting::DepositRequired in create_collection causes a WrongSetting error

Question

I'm integrating my own pallet with Substrate's NFTs pallet. In my logic I try to create a collection with specific settings as follows:

let nft_collection_id = <T as Config<I>>::Nfts::create_collection(
                &who, 
                &who, 
                &CollectionConfig {
                    settings: CollectionSettings::from_disabled(
                        CollectionSetting::TransferableItems | CollectionSetting::DepositRequired
                    ),
                    max_supply: None,
                    mint_settings: MintSettings::default(),
                },
            )?;

This results in the error WrongSetting. I can say that the error is caused by DepositRequired, since everything works if I remove this setting. So I'm having a hard time trying to understand why I'm getting this error.

In the a test of the Nfts pallet itself a very similar thing is done:

let collection_id = 1;
        assert_ok!(Nfts::force_create(
            RuntimeOrigin::root(),
            account(1),
            collection_config_from_disabled_settings(
                CollectionSetting::TransferableItems | CollectionSetting::DepositRequired
            )
        ));

The only difference is that I'm using create_collection instead of force_create. Is that the reason why I'm getting this error?

Answer 1

In Substrate is a recomended security practice to take a deposit from the user for any storage items they place on chain.

The create_collection function you are calling uses a deposit to create a collection, so if you try to disable it throws an error. The force_create works because is a special extrinsic that can be called only with special privilegies(See the code)

        // DepositRequired can be disabled by calling the force_create() only
        ensure!(
            !config.has_disabled_setting(CollectionSetting::DepositRequired),
            Error::<T, I>::WrongSetting
        );

The deposit you have to reserve to create a collection is specified in the Config file of the NFT pallet:

/// The basic amount of funds that must be reserved for collection.
#[pallet::constant]
type CollectionDeposit: Get<DepositBalanceOf<Self, I>>;