Create AccountIndex from number (#304)

packages/api-observable/src/Combined.ts

@@ -29,8 +29,8 @@ export default class ApiCombined extends ApiCalls {
             : new BN(0);
 
           return this.combine(
-            Array(lastIndex.toNumber()).map((_, i): Observable<Array<AccountId> | undefined> =>
-              this.getAccountEnumSet(i)
+            Array(lastIndex.div(ENUMSET_SIZE).toNumber()).map((_, i): Observable<Array<AccountId> | undefined> =>
+              this.getAccountEnumSet(i * ENUMSET_SIZE.toNumber())
             ),
             (...all: Array<Array<AccountId> | undefined>) => {
               return all.reduce((result, list = [], outerIndex: number) => {

packages/api-observable/src/Queries.ts

@@ -9,9 +9,7 @@ import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 import storage from '@polkadot/storage/static';
 import { AccountId, AccountIndex, Balance, bool as Bool, BlockNumber, Index, Moment, Perbill, PropIndex, ReferendumIndex, u32 } from '@polkadot/types/index';
-import { ENUMSET_SIZE } from '@polkadot/types/AccountIndex';
-import { Tuple, U8a, Vector } from '@polkadot/types/codec';
-import bnToU8a from '@polkadot/util/bn/toU8a';
+import { Tuple, Vector } from '@polkadot/types/codec';
 
 import ApiBase from './Base';
 import { RxProposal, RxProposalDeposits, RxReferendum } from './classes';
@@ -48,12 +46,8 @@ export default class ApiQueries extends ApiBase {
     return this.rawStorage(storage.democracy.nextTally);
   }
 
-  getAccountEnumSet = (_index: AccountIndex | BN | number): Observable<Array<AccountId> | undefined> => {
-    const index = _index instanceof AccountIndex
-      ? _index.toBn().div(ENUMSET_SIZE)
-      : _index;
-
-    return this.rawStorage(storage.balances.enumSet, new U8a(bnToU8a(index, 32, true)));
+  getAccountEnumSet = (index: AccountIndex | BN | number): Observable<Array<AccountId> | undefined> => {
+    return this.rawStorage(storage.balances.enumSet, index);
   }
 
   nextAccountEnumSet = (): Observable<AccountIndex | undefined> => {

packages/types/src/AccountIndex.spec.js

@@ -0,0 +1,26 @@
+// Copyright 2017-2018 @polkadot/types authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import BN from 'bn.js';
+import AccountIndex from './AccountIndex';
+
+describe('AccountIndex', () => {
+  it('creates a BN representation', () => {
+    expect(
+      new AccountIndex([0xfd, 17, 18, 19, 20]).toBn().toString()
+    ).toEqual('336794129');
+  });
+
+  it('constructs 2-byte from number', () => {
+    expect(
+      new AccountIndex(256 * 1).toString()
+    ).toEqual('25GUyk');
+  });
+
+  it('constructs from number', () => {
+    expect(
+      new AccountIndex(new BN(336794129)).toString()
+    ).toEqual('3N5RJXxJhgRhxu');
+  });
+});

packages/types/src/AccountIndex.ts

@@ -14,6 +14,9 @@ import { AnyU8a } from './types';
 import U8a from './codec/U8a';
 import u8aToBn from '@polkadot/util/u8a/toBn';
 import bnToU8a from '@polkadot/util/bn/toU8a';
+import isNumber from '@polkadot/util/is/number';
+import isBn from '@polkadot/util/is/bn';
+import bnToBn from '@polkadot/util/bn/toBn';
 
 export const ENUMSET_SIZE = new BN(64);
 
@@ -21,13 +24,13 @@ export const ENUMSET_SIZE = new BN(64);
 // for an Account. We extends from U8a which is basically
 // just a Uint8Array wrapper.
 export default class AccountIndex extends U8a {
-  constructor (value: AnyU8a = new Uint8Array()) {
+  constructor (value: BN | number | AnyU8a = new Uint8Array()) {
     super(
       AccountIndex.decodeAccountIndex(value)
     );
   }
 
-  static decodeAccountIndex (value: AnyU8a): Uint8Array {
+  static decodeAccountIndex (value: BN | number | AnyU8a): Uint8Array {
     if (value instanceof U8a) {
       return value.raw;
     } else if (Array.isArray(value)) {
@@ -40,6 +43,21 @@ export default class AccountIndex extends U8a {
       const [offset, length] = AccountIndex.readLength(value);
 
       return value.subarray(offset, offset + length);
+    } else if (isNumber(value) || isBn(value)) {
+      const index = bnToBn(value);
+      const bitLength = index.ltn(1 << 8)
+        ? 8
+        : (
+          index.ltn(1 << 16)
+            ? 16
+            : (
+              index.ltn(1 << 32)
+                ? 32
+                : 64
+            )
+        );
+
+      return bnToU8a(index, bitLength, true);
     } else if (isHex(value)) {
       return hexToU8a(value);
     }