Auto-incremental CollectionId

frame/uniques/src/benchmarking.rs

@@ -42,13 +42,10 @@ fn create_collection<T: Config<I>, I: 'static>(
 	let caller_lookup = T::Lookup::unlookup(caller.clone());
 	let collection = T::Helper::collection(0);
 	T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
-	assert!(Uniques::<T, I>::force_create(
-		SystemOrigin::Root.into(),
-		collection,
-		caller_lookup.clone(),
-		false,
-	)
-	.is_ok());
+	assert!(
+		Uniques::<T, I>::force_create(SystemOrigin::Root.into(), caller_lookup.clone(), false,)
+			.is_ok()
+	);
 	(collection, caller, caller_lookup)
 }
 
@@ -143,7 +140,7 @@ benchmarks_instance_pallet! {
 		whitelist_account!(caller);
 		let admin = T::Lookup::unlookup(caller.clone());
 		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
-		let call = Call::<T, I>::create { collection, admin };
+		let call = Call::<T, I>::create { admin };
 	}: { call.dispatch_bypass_filter(origin)? }
 	verify {
 		assert_last_event::<T, I>(Event::Created { collection: T::Helper::collection(0), creator: caller.clone(), owner: caller }.into());
@@ -152,7 +149,7 @@ benchmarks_instance_pallet! {
 	force_create {
 		let caller: T::AccountId = whitelisted_caller();
 		let caller_lookup = T::Lookup::unlookup(caller.clone());
-	}: _(SystemOrigin::Root, T::Helper::collection(0), caller_lookup, true)
+	}: _(SystemOrigin::Root, caller_lookup, true)
 	verify {
 		assert_last_event::<T, I>(Event::ForceCreated { collection: T::Helper::collection(0), owner: caller }.into());
 	}
@@ -408,6 +405,16 @@ benchmarks_instance_pallet! {
 		}.into());
 	}
 
+	try_increment_id {
+		let (_, caller, _) = create_collection::<T, I>();
+		Uniques::<T, I>::set_next_id(0);
+	}: _(SystemOrigin::Signed(caller.clone()))
+	verify {
+		assert_last_event::<T, I>(Event::NextCollectionIdIncremented {
+			next_id: 1u32.into()
+	}.into());
+  }
+
 	set_price {
 		let (collection, caller, _) = create_collection::<T, I>();
 		let (item, ..) = mint_item::<T, I>(0);

frame/uniques/src/functions.rs

@@ -88,7 +88,12 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			},
 		);
 
+		let next_id = collection.saturating_add(1u32.into());
+
 		CollectionAccount::<T, I>::insert(&owner, &collection, ());
+		NextCollectionId::<T, I>::set(next_id);
+
+		Self::deposit_event(Event::NextCollectionIdIncremented { next_id });
 		Self::deposit_event(event);
 		Ok(())
 	}
@@ -208,6 +213,16 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(())
 	}
 
+	#[cfg(any(test, feature = "runtime-benchmarks"))]
+	pub fn set_next_id(count: u32) {
+		NextCollectionId::<T, I>::set(count.into());
+	}
+
+	#[cfg(test)]
+	pub fn get_next_id() -> T::CollectionId {
+		NextCollectionId::<T, I>::get()
+	}
+
 	pub fn do_set_price(
 		collection: T::CollectionId,
 		item: T::ItemId,

frame/uniques/src/lib.rs

@@ -56,6 +56,8 @@ use sp_runtime::{
 };
 use sp_std::prelude::*;
 
+use sp_runtime::traits::AtLeast32BitUnsigned;
+
 pub use pallet::*;
 pub use types::*;
 pub use weights::WeightInfo;
@@ -92,7 +94,12 @@ pub mod pallet {
 		type Event: From<Event<Self, I>> + IsType<<Self as frame_system::Config>::Event>;
 
 		/// Identifier for the collection of item.
-		type CollectionId: Member + Parameter + MaxEncodedLen + Copy;
+		type CollectionId: Member
+			+ Parameter
+			+ MaxEncodedLen
+			+ Copy
+			+ Default
+			+ AtLeast32BitUnsigned;
 
 		/// The type used to identify a unique item within a collection.
 		type ItemId: Member + Parameter + MaxEncodedLen + Copy;
@@ -266,6 +273,12 @@ pub mod pallet {
 	pub(super) type CollectionMaxSupply<T: Config<I>, I: 'static = ()> =
 		StorageMap<_, Blake2_128Concat, T::CollectionId, u32, OptionQuery>;
 
+	#[pallet::storage]
+	/// Stores the `CollectionId` that is going to be used for the next collection.
+	/// This gets incremented by 1 when creating a collection.
+	pub(super) type NextCollectionId<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, T::CollectionId, ValueQuery>;
+
 	#[pallet::event]
 	#[pallet::generate_deposit(pub(super) fn deposit_event)]
 	pub enum Event<T: Config<I>, I: 'static = ()> {
@@ -357,6 +370,8 @@ pub mod pallet {
 		OwnershipAcceptanceChanged { who: T::AccountId, maybe_collection: Option<T::CollectionId> },
 		/// Max supply has been set for a collection.
 		CollectionMaxSupplySet { collection: T::CollectionId, max_supply: u32 },
+		/// Event gets emmited when the `NextCollectionId` gets incremented.
+		NextCollectionIdIncremented { next_id: T::CollectionId },
 		/// The price was set for the instance.
 		ItemPriceSet {
 			collection: T::CollectionId,
@@ -408,6 +423,10 @@ pub mod pallet {
 		MaxSupplyAlreadySet,
 		/// The provided max supply is less to the amount of items a collection already has.
 		MaxSupplyTooSmall,
+		/// The `CollectionId` in `NextCollectionId` is not being used.
+		///
+		/// This means that you can directly proceed to call `create`.
+		NextIdNotUsed,
 		/// The given item ID is unknown.
 		UnknownItem,
 		/// Item is not for sale.
@@ -439,7 +458,6 @@ pub mod pallet {
 		/// `ItemDeposit` funds of sender are reserved.
 		///
 		/// Parameters:
-		/// - `collection`: The identifier of the new collection. This must not be currently in use.
 		/// - `admin`: The admin of this collection. The admin is the initial address of each
 		/// member of the collection's admin team.
 		///
@@ -449,9 +467,10 @@ pub mod pallet {
 		#[pallet::weight(T::WeightInfo::create())]
 		pub fn create(
 			origin: OriginFor<T>,
-			collection: T::CollectionId,
 			admin: <T::Lookup as StaticLookup>::Source,
 		) -> DispatchResult {
+			let collection = NextCollectionId::<T, I>::get();
+
 			let owner = T::CreateOrigin::ensure_origin(origin, &collection)?;
 			let admin = T::Lookup::lookup(admin)?;
 
@@ -473,7 +492,6 @@ pub mod pallet {
 		///
 		/// Unlike `create`, no funds are reserved.
 		///
-		/// - `collection`: The identifier of the new item. This must not be currently in use.
 		/// - `owner`: The owner of this collection of items. The owner has full superuser
 		///   permissions
 		/// over this item, but may later change and configure the permissions using
@@ -485,13 +503,14 @@ pub mod pallet {
 		#[pallet::weight(T::WeightInfo::force_create())]
 		pub fn force_create(
 			origin: OriginFor<T>,
-			collection: T::CollectionId,
 			owner: <T::Lookup as StaticLookup>::Source,
 			free_holding: bool,
 		) -> DispatchResult {
 			T::ForceOrigin::ensure_origin(origin)?;
 			let owner = T::Lookup::lookup(owner)?;
 
+			let collection = NextCollectionId::<T, I>::get();
+
 			Self::do_create_collection(
 				collection,
 				owner.clone(),
@@ -502,6 +521,31 @@ pub mod pallet {
 			)
 		}
 
+		/// Increments the `CollectionId` stored in `NextCollectionId`.
+		///
+		/// This is only callable when the next `CollectionId` is already being
+		/// used for some other collection.
+		///
+		/// The origin must be Signed and the sender must have sufficient funds
+		/// free.
+		///
+		/// Emits `NextCollectionIdIncremented` event when successful.
+		///
+		/// Weight: `O(1)`
+		#[pallet::weight(T::WeightInfo::try_increment_id())]
+		pub fn try_increment_id(origin: OriginFor<T>) -> DispatchResult {
+			ensure_signed(origin)?;
+			ensure!(
+				Collection::<T, I>::contains_key(NextCollectionId::<T, I>::get()),
+				Error::<T, I>::NextIdNotUsed
+			);
+
+			let next_id = NextCollectionId::<T, I>::get().saturating_add(1u32.into());
+			NextCollectionId::<T, I>::set(next_id);
+			Self::deposit_event(Event::NextCollectionIdIncremented { next_id });
+			Ok(())
+		}
+
 		/// Destroy a collection of fungible items.
 		///
 		/// The origin must conform to `ForceOrigin` or must be `Signed` and the sender must be the