packages/api-derive/src/staking/validators.ts
// Copyright 2017-2024 @polkadot/api-derive authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { Observable } from 'rxjs';
import type { AccountId } from '@polkadot/types/interfaces';
import type { DeriveApi, DeriveStakingValidators } from '../types.js';
import { combineLatest, map, of, switchMap } from 'rxjs';
import { memo } from '../util/index.js';
export function nextElected (instanceId: string, api: DeriveApi): () => Observable<AccountId[]> {
return memo(instanceId, (): Observable<AccountId[]> =>
api.query.staking.erasStakersPaged
? api.derive.session.indexes().pipe(
// only populate for next era in the last session, so track both here - entries are not
// subscriptions, so we need a trigger - currentIndex acts as that trigger to refresh
switchMap(({ currentEra }) => api.query.staking.erasStakersPaged.keys(currentEra)),
map((keys) => keys.map(({ args: [, accountId] }) => accountId))
)
: api.query.staking['currentElected']<AccountId[]>()
);
}
/**
* @description Retrieve latest list of validators
*/
export function validators (instanceId: string, api: DeriveApi): () => Observable<DeriveStakingValidators> {
return memo(instanceId, (): Observable<DeriveStakingValidators> =>
// Sadly the node-template is (for some obscure reason) not comprehensive, so while the derive works
// in all actual real-world deployed chains, it does create some confusion for limited template chains
combineLatest([
api.query.session
? api.query.session.validators()
: of([]),
api.query.staking
? api.derive.staking.nextElected()
: of([])
]).pipe(
map(([validators, nextElected]): DeriveStakingValidators => ({
nextElected: nextElected.length
? nextElected
: validators,
validators
}))
));
}