improve staking interface methods

frame/nomination-pools/benchmarking/src/lib.rs

@@ -684,12 +684,12 @@ frame_benchmarking::benchmarks! {
 			.collect();
 
 		assert_ok!(T::Staking::nominate(&pool_account, validators));
-		assert!(T::Staking::nominations(Pools::<T>::create_bonded_account(1)).is_some());
+		assert!(T::Staking::nominations(&Pools::<T>::create_bonded_account(1)).is_some());
 
 		whitelist_account!(depositor);
 	}:_(RuntimeOrigin::Signed(depositor.clone()), 1)
 	verify {
-		assert!(T::Staking::nominations(Pools::<T>::create_bonded_account(1)).is_none());
+		assert!(T::Staking::nominations(&Pools::<T>::create_bonded_account(1)).is_none());
 	}
 
 	set_commission {

frame/nomination-pools/src/mock.rs

@@ -67,6 +67,14 @@ impl sp_staking::StakingInterface for StakingMock {
 		BondingDuration::get()
 	}
 
+	fn status(
+		_: &Self::AccountId,
+	) -> Result<sp_staking::StakerStatus<Self::AccountId>, DispatchError> {
+		Nominations::get()
+			.map(|noms| sp_staking::StakerStatus::Nominator(noms))
+			.ok_or(DispatchError::Other("NotStash"))
+	}
+
 	fn bond_extra(who: &Self::AccountId, extra: Self::Balance) -> DispatchResult {
 		let mut x = BondedBalanceMap::get();
 		x.get_mut(who).map(|v| *v += extra);
@@ -108,15 +116,15 @@ impl sp_staking::StakingInterface for StakingMock {
 	}
 
 	#[cfg(feature = "runtime-benchmarks")]
-	fn nominations(_: Self::AccountId) -> Option<Vec<Self::AccountId>> {
+	fn nominations(_: &Self::AccountId) -> Option<Vec<Self::AccountId>> {
 		Nominations::get()
 	}
 
 	fn stash_by_ctrl(_controller: &Self::AccountId) -> Result<Self::AccountId, DispatchError> {
 		unimplemented!("method currently not used in testing")
 	}
 
-	fn stake(who: &Self::AccountId) -> Result<Stake<Self>, DispatchError> {
+	fn stake(who: &Self::AccountId) -> Result<Stake<Balance>, DispatchError> {
 		match (
 			UnbondingBalanceMap::get().get(who).copied(),
 			BondedBalanceMap::get().get(who).copied(),

frame/staking/src/lib.rs

@@ -311,6 +311,7 @@ use sp_runtime::{
 	traits::{AtLeast32BitUnsigned, Convert, Saturating, StaticLookup, Zero},
 	Perbill, Perquintill, Rounding, RuntimeDebug,
 };
+pub use sp_staking::StakerStatus;
 use sp_staking::{
 	offence::{Offence, OffenceError, ReportOffence},
 	EraIndex, SessionIndex,
@@ -381,18 +382,6 @@ impl<AccountId: Ord> Default for EraRewardPoints<AccountId> {
 	}
 }
 
-/// Indicates the initial status of the staker.
-#[derive(RuntimeDebug, TypeInfo)]
-#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize, Clone))]
-pub enum StakerStatus<AccountId> {
-	/// Chilling.
-	Idle,
-	/// Declared desire in validating or already participating in it.
-	Validator,
-	/// Nominating for a group of other stakers.
-	Nominator(Vec<AccountId>),
-}
-
 /// A destination account for payment.
 #[derive(PartialEq, Eq, Copy, Clone, Encode, Decode, RuntimeDebug, TypeInfo, MaxEncodedLen)]
 pub enum RewardDestination<AccountId> {

frame/staking/src/pallet/impls.rs

@@ -22,6 +22,7 @@ use frame_election_provider_support::{
 	SortedListProvider, VoteWeight, VoterOf,
 };
 use frame_support::{
+	defensive,
 	dispatch::WithPostDispatchInfo,
 	pallet_prelude::*,
 	traits::{
@@ -1608,7 +1609,7 @@ impl<T: Config> StakingInterface for Pallet<T> {
 		Self::current_era().unwrap_or(Zero::zero())
 	}
 
-	fn stake(who: &Self::AccountId) -> Result<Stake<Self>, DispatchError> {
+	fn stake(who: &Self::AccountId) -> Result<Stake<BalanceOf<T>>, DispatchError> {
 		Self::bonded(who)
 			.and_then(|c| Self::ledger(c))
 			.map(|l| Stake { total: l.total, active: l.active })
@@ -1662,8 +1663,33 @@ impl<T: Config> StakingInterface for Pallet<T> {
 		Self::nominate(RawOrigin::Signed(ctrl).into(), targets)
 	}
 
+	fn status(
+		who: &Self::AccountId,
+	) -> Result<sp_staking::StakerStatus<Self::AccountId>, DispatchError> {
+		let is_bonded = Self::bonded(who).is_some();
+		if !is_bonded {
+			return Err(Error::<T>::NotStash.into())
+		}
+
+		let is_validator = Validators::<T>::contains_key(&who);
+		let is_nominator = Nominators::<T>::get(&who);
+
+		use sp_staking::StakerStatus;
+		match (is_validator, is_nominator.is_some()) {
+			(false, false) => Ok(StakerStatus::Idle),
+			(true, false) => Ok(StakerStatus::Validator),
+			(false, true) => Ok(StakerStatus::Nominator(
+				is_nominator.expect("is checked above; qed").targets.into_inner(),
+			)),
+			(true, true) => {
+				defensive!("cannot be both validators and nominator");
+				Err(Error::<T>::BadState.into())
+			},
+		}
+	}
+
 	sp_staking::runtime_benchmarks_enabled! {
-		fn nominations(who: Self::AccountId) -> Option<Vec<T::AccountId>> {
+		fn nominations(who: &Self::AccountId) -> Option<Vec<T::AccountId>> {
 			Nominators::<T>::get(who).map(|n| n.targets.into_inner())
 		}
 

frame/staking/src/tests.rs

@@ -5824,4 +5824,27 @@ mod staking_interface {
 			));
 		});
 	}
+
+	#[test]
+	fn status() {
+		ExtBuilder::default().build_and_execute(|| {
+			// stash of a validator is identified as a validator
+			assert_eq!(Staking::status(&11).unwrap(), StakerStatus::Validator);
+			// .. but not the controller.
+			assert!(Staking::status(&10).is_err());
+
+			// stash of nominator is identified as a nominator
+			assert_eq!(Staking::status(&101).unwrap(), StakerStatus::Nominator(vec![11, 21]));
+			// .. but not the controller.
+			assert!(Staking::status(&100).is_err());
+
+			// stash of chilled is identified as a chilled
+			assert_eq!(Staking::status(&41).unwrap(), StakerStatus::Idle);
+			// .. but not the controller.
+			assert!(Staking::status(&40).is_err());
+
+			// random other account.
+			assert!(Staking::status(&42).is_err());
+		})
+	}
 }

primitives/staking/Cargo.toml

@@ -13,6 +13,7 @@ readme = "README.md"
 targets = ["x86_64-unknown-linux-gnu"]
 
 [dependencies]
+serde = { version = "1.0.136", optional = true }
 codec = { package = "parity-scale-codec", version = "3.2.2", default-features = false, features = ["derive"] }
 scale-info = { version = "2.5.0", default-features = false, features = ["derive"] }
 sp-core = { version = "7.0.0", default-features = false, path = "../core" }
@@ -22,6 +23,7 @@ sp-std = { version = "5.0.0", default-features = false, path = "../std" }
 [features]
 default = ["std"]
 std = [
+	"serde",
 	"codec/std",
 	"scale-info/std",
 	"sp-core/std",

primitives/staking/src/lib.rs

@@ -20,6 +20,8 @@
 //! A crate which contains primitives that are useful for implementation that uses staking
 //! approaches in general. Definitions related to sessions, slashing, etc go here.
 
+use scale_info::TypeInfo;
+use sp_core::RuntimeDebug;
 use sp_runtime::{DispatchError, DispatchResult};
 use sp_std::{collections::btree_map::BTreeMap, vec::Vec};
 
@@ -31,6 +33,18 @@ pub type SessionIndex = u32;
 /// Counter for the number of eras that have passed.
 pub type EraIndex = u32;
 
+/// Representation of the status of a staker.
+#[derive(RuntimeDebug, TypeInfo)]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize, PartialEq, Eq, Clone))]
+pub enum StakerStatus<AccountId> {
+	/// Chilling.
+	Idle,
+	/// Declaring desire in validate, i.e author blocks.
+	Validator,
+	/// Declaring desire to nominate, delegate, or generally approve of the given set of others.
+	Nominator(Vec<AccountId>),
+}
+
 /// Trait describing something that implements a hook for any operations to perform when a staker is
 /// slashed.
 pub trait OnStakerSlash<AccountId, Balance> {
@@ -57,7 +71,7 @@ impl<AccountId, Balance> OnStakerSlash<AccountId, Balance> for () {
 
 /// A struct that reflects stake that an account has in the staking system. Provides a set of
 /// methods to operate on it's properties. Aimed at making `StakingInterface` more concise.
-pub struct Stake<T: StakingInterface + ?Sized> {
+pub struct Stake<Balance> {
 	/// The total stake that `stash` has in the staking system. This includes the
 	/// `active` stake, and any funds currently in the process of unbonding via
 	/// [`StakingInterface::unbond`].
@@ -67,10 +81,10 @@ pub struct Stake<T: StakingInterface + ?Sized> {
 	/// This is only guaranteed to reflect the amount locked by the staking system. If there are
 	/// non-staking locks on the bonded pair's balance this amount is going to be larger in
 	/// reality.
-	pub total: T::Balance,
+	pub total: Balance,
 	/// The total amount of the stash's balance that will be at stake in any forthcoming
 	/// rounds.
-	pub active: T::Balance,
+	pub active: Balance,
 }
 
 /// A generic representation of a staking implementation.
@@ -109,21 +123,25 @@ pub trait StakingInterface {
 	/// This should be the latest planned era that the staking system knows about.
 	fn current_era() -> EraIndex;
 
-	/// Returns the stake of `who`.
-	fn stake(who: &Self::AccountId) -> Result<Stake<Self>, DispatchError>;
+	/// Returns the [`Stake`] of `who`.
+	fn stake(who: &Self::AccountId) -> Result<Stake<Self::Balance>, DispatchError>;
 
+	/// Total stake of a staker, `Err` if not a staker.
 	fn total_stake(who: &Self::AccountId) -> Result<Self::Balance, DispatchError> {
 		Self::stake(who).map(|s| s.total)
 	}
 
+	/// Total active portion of a staker's [`Stake`], `Err` if not a staker.
 	fn active_stake(who: &Self::AccountId) -> Result<Self::Balance, DispatchError> {
 		Self::stake(who).map(|s| s.active)
 	}
 
+	/// Returns whether a staker is unbonding, `Err` if not a staker at all.
 	fn is_unbonding(who: &Self::AccountId) -> Result<bool, DispatchError> {
 		Self::stake(who).map(|s| s.active != s.total)
 	}
 
+	/// Returns whether a staker is FULLY unbonding, `Err` if not a staker at all.
 	fn fully_unbond(who: &Self::AccountId) -> DispatchResult {
 		Self::unbond(who, Self::stake(who)?.active)
 	}
@@ -174,9 +192,17 @@ pub trait StakingInterface {
 	/// Checks whether an account `staker` has been exposed in an era.
 	fn is_exposed_in_era(who: &Self::AccountId, era: &EraIndex) -> bool;
 
+	/// Return the status of the given staker, `None` if not staked at all.
+	fn status(who: &Self::AccountId) -> Result<StakerStatus<Self::AccountId>, DispatchError>;
+
 	/// Get the nominations of a stash, if they are a nominator, `None` otherwise.
 	#[cfg(feature = "runtime-benchmarks")]
-	fn nominations(who: Self::AccountId) -> Option<Vec<Self::AccountId>>;
+	fn nominations(who: &Self::AccountId) -> Option<Vec<Self::AccountId>> {
+		match Self::status(who) {
+			Ok(StakerStatus::Nominator(t)) => Some(t),
+			_ => None,
+		}
+	}
 
 	#[cfg(feature = "runtime-benchmarks")]
 	fn add_era_stakers(