Auto-incremental CollectionId (#11796)

* autoincrementing CollectionId

* fix

* benchmarking fix

* fmt

* fix

* update before checking

* fmt

* fix

* fmt

* commit

* tests & fix

* fix

* commit

* docs

* safe math

* unexpose function

* benchmark

* fmt

* better naming

* fix?

* merge fixes

* fmt

* ".git/.scripts/bench-bot.sh" pallet dev pallet_uniques

* wrong weight

* Update frame/uniques/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update frame/uniques/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* using substrate trait instead of num-traits

* remove unnecessary trait

* emit NextCollectionIdIncremented in do_create_collection

* fix in benchmarks

* check for event & group import

* docs

Co-authored-by: Sergej Sakač <sergejsakac@Sergejs-MacBook-Air.local>
Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/frame/uniques/src/lib.rs

@@ -51,7 +51,7 @@ use frame_support::{
 };
 use frame_system::Config as SystemConfig;
 use sp_runtime::{
-	traits::{Saturating, StaticLookup, Zero},
+	traits::{AtLeast32BitUnsigned, Saturating, StaticLookup, Zero},
 	ArithmeticError, RuntimeDebug,
 };
 use sp_std::prelude::*;
@@ -92,7 +92,12 @@ 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 +271,12 @@ 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 whenever a new collection is created.
+	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 +368,8 @@ 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 +421,10 @@ 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 +456,6 @@ 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 +465,10 @@ 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 +490,6 @@ 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 +501,14 @@ 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 +519,31 @@ 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