Jaco
ff3882f5f7
* Bump common (w/ rxjs 7) * Adjust * pre bump * Cleanup imports * Add missing switchMap * CHANGELOG * Remove duplicate imports * Bump common * Direct rxjs import
46 lines
1.6 KiB
TypeScript
46 lines
1.6 KiB
TypeScript
// Copyright 2017-2021 @polkadot/api-derive authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { Observable } from 'rxjs';
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import type { ApiInterfaceRx } from '@polkadot/api/types';
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import type { HeaderExtended } from '../type/types';
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import { catchError, combineLatest, map, of } from 'rxjs';
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import { createHeaderExtended } from '../type';
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import { memo } from '../util';
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/**
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* @name getHeader
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* @param {( Uint8Array | string )} hash - A block hash as U8 array or string.
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* @returns An array containing the block header and the block author
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* @description Get a specific block header and extend it with the author
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* @example
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* <BR>
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*
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* ```javascript
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* const { author, number } = await api.derive.chain.getHeader('0x123...456');
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*
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* console.log(`block #${number} was authored by ${author}`);
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* ```
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*/
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export function getHeader (instanceId: string, api: ApiInterfaceRx): (hash: Uint8Array | string) => Observable<HeaderExtended | undefined> {
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return memo(instanceId, (hash: Uint8Array | string): Observable<HeaderExtended | undefined> =>
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combineLatest([
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api.rpc.chain.getHeader(hash),
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api.query.session
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? api.query.session.validators.at(hash)
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: of([])
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]).pipe(
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map(([header, validators]): HeaderExtended =>
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createHeaderExtended(header.registry, header, validators)
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),
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catchError((): Observable<undefined> =>
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// where rpc.chain.getHeader throws, we will land here - it can happen that
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// we supplied an invalid hash. (Due to defaults, storeage will have an
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// empty value, so only the RPC is affected). So return undefined
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of()
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)
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));
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}
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