45 lines
1.6 KiB
TypeScript
45 lines
1.6 KiB
TypeScript
// Copyright 2017-2020 @polkadot/api-derive authors & contributors
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// This software may be modified and distributed under the terms
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// of the Apache-2.0 license. See the LICENSE file for details.
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import { ApiInterfaceRx } from '@polkadot/api/types';
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import { Observable, combineLatest, of } from 'rxjs';
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import { catchError, map } from 'rxjs/operators';
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import { SignedBlockExtended } from '../type';
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import { memo } from '../util';
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/**
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* @name getBlock
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* @param {( Uint8Array | string )} hash - A block hash as U8 array or string.
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* @description Get a specific block (e.g. rpc.chain.getBlock) 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 (api: ApiInterfaceRx): (hash: Uint8Array | string) => Observable<SignedBlockExtended | undefined> {
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return memo((hash: Uint8Array | string): Observable<SignedBlockExtended | undefined> =>
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combineLatest([
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api.rpc.chain.getBlock(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(([signedBlock, validators]): SignedBlockExtended =>
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new SignedBlockExtended(api.registry, signedBlock, 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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