Allow to clear nft attributes via traits

frame/nfts/src/impl_nonfungibles.rs

@@ -237,6 +237,49 @@ impl<T: Config<I>, I: 'static> Mutate<<T as SystemConfig>::AccountId, ItemConfig
 			})
 		})
 	}
+
+	fn clear_attribute(
+		collection: &Self::CollectionId,
+		item: &Self::ItemId,
+		key: &[u8],
+	) -> DispatchResult {
+		Self::do_clear_attribute(
+			None,
+			*collection,
+			Some(*item),
+			AttributeNamespace::Pallet,
+			Self::construct_attribute_key(key.to_vec())?,
+		)
+	}
+
+	fn clear_typed_attribute<K: Encode>(
+		collection: &Self::CollectionId,
+		item: &Self::ItemId,
+		key: &K,
+	) -> DispatchResult {
+		key.using_encoded(|k| {
+			<Self as Mutate<T::AccountId, ItemConfig>>::clear_attribute(collection, item, k)
+		})
+	}
+
+	fn clear_collection_attribute(collection: &Self::CollectionId, key: &[u8]) -> DispatchResult {
+		Self::do_clear_attribute(
+			None,
+			*collection,
+			None,
+			AttributeNamespace::Pallet,
+			Self::construct_attribute_key(key.to_vec())?,
+		)
+	}
+
+	fn clear_typed_collection_attribute<K: Encode>(
+		collection: &Self::CollectionId,
+		key: &K,
+	) -> DispatchResult {
+		key.using_encoded(|k| {
+			<Self as Mutate<T::AccountId, ItemConfig>>::clear_collection_attribute(collection, k)
+		})
+	}
 }
 
 impl<T: Config<I>, I: 'static> Transfer<T::AccountId> for Pallet<T, I> {

frame/nfts/src/tests.rs

@@ -1012,6 +1012,22 @@ fn validate_deposit_required_setting() {
 		assert_eq!(Balances::reserved_balance(1), 0);
 		assert_eq!(Balances::reserved_balance(2), 3);
 		assert_eq!(Balances::reserved_balance(3), 3);
+
+		assert_ok!(
+			<Nfts as Mutate<<Test as SystemConfig>::AccountId, ItemConfig>>::clear_attribute(
+				&0,
+				&0,
+				&[3],
+			)
+		);
+		assert_eq!(
+			attributes(0),
+			vec![
+				(Some(0), AttributeNamespace::CollectionOwner, bvec![0], bvec![0]),
+				(Some(0), AttributeNamespace::ItemOwner, bvec![1], bvec![0]),
+				(Some(0), AttributeNamespace::Account(3), bvec![2], bvec![0]),
+			]
+		);
 	});
 }
 

frame/support/src/traits/tokens/nonfungible_v2.rs

@@ -127,6 +127,20 @@ pub trait Mutate<AccountId, ItemConfig>: Inspect<AccountId> {
 	) -> DispatchResult {
 		key.using_encoded(|k| value.using_encoded(|v| Self::set_attribute(item, k, v)))
 	}
+
+	/// Clear attribute of `item`'s `key`.
+	///
+	/// By default, this is not a supported operation.
+	fn clear_attribute(_item: &Self::ItemId, _key: &[u8]) -> DispatchResult {
+		Err(TokenError::Unsupported.into())
+	}
+
+	/// Attempt to clear the strongly-typed attribute of `item`'s `key`.
+	///
+	/// By default this just attempts to use `clear_attribute`.
+	fn clear_typed_attribute<K: Encode>(item: &Self::ItemId, key: &K) -> DispatchResult {
+		key.using_encoded(|k| Self::clear_attribute(item, k))
+	}
 }
 
 /// Trait for transferring a non-fungible item.
@@ -234,6 +248,16 @@ impl<
 			value,
 		)
 	}
+	fn clear_attribute(item: &Self::ItemId, key: &[u8]) -> DispatchResult {
+		<F as nonfungibles::Mutate<AccountId, ItemConfig>>::clear_attribute(&A::get(), item, key)
+	}
+	fn clear_typed_attribute<K: Encode>(item: &Self::ItemId, key: &K) -> DispatchResult {
+		<F as nonfungibles::Mutate<AccountId, ItemConfig>>::clear_typed_attribute(
+			&A::get(),
+			item,
+			key,
+		)
+	}
 }
 
 impl<

frame/support/src/traits/tokens/nonfungibles_v2.rs

@@ -244,6 +244,45 @@ pub trait Mutate<AccountId, ItemConfig>: Inspect<AccountId> {
 			value.using_encoded(|v| Self::set_collection_attribute(collection, k, v))
 		})
 	}
+
+	/// Clear attribute of `item` of `collection`'s `key`.
+	///
+	/// By default, this is not a supported operation.
+	fn clear_attribute(
+		_collection: &Self::CollectionId,
+		_item: &Self::ItemId,
+		_key: &[u8],
+	) -> DispatchResult {
+		Err(TokenError::Unsupported.into())
+	}
+
+	/// Attempt to clear the strongly-typed attribute of `item` of `collection`'s `key`.
+	///
+	/// By default this just attempts to use `clear_attribute`.
+	fn clear_typed_attribute<K: Encode>(
+		collection: &Self::CollectionId,
+		item: &Self::ItemId,
+		key: &K,
+	) -> DispatchResult {
+		key.using_encoded(|k| Self::clear_attribute(collection, item, k))
+	}
+
+	/// Clear attribute of `collection`'s `key`.
+	///
+	/// By default, this is not a supported operation.
+	fn clear_collection_attribute(_collection: &Self::CollectionId, _key: &[u8]) -> DispatchResult {
+		Err(TokenError::Unsupported.into())
+	}
+
+	/// Attempt to clear the strongly-typed attribute of `collection`'s `key`.
+	///
+	/// By default this just attempts to use `clear_attribute`.
+	fn clear_typed_collection_attribute<K: Encode>(
+		collection: &Self::CollectionId,
+		key: &K,
+	) -> DispatchResult {
+		key.using_encoded(|k| Self::clear_collection_attribute(collection, k))
+	}
 }
 
 /// Trait for transferring non-fungible sets of items.