Return ReferendumIndex along with info (derive) (#669)

* Return ReferendumIndex along with info (derive)

* Rename index

* Doc rename

packages/api-derive/src/democracy/referendumInfo.ts

@@ -0,0 +1,44 @@
+// Copyright 2017-2019 @polkadot/api-derive authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import BN from 'bn.js';
+import { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+import { ApiInterface$Rx } from '@polkadot/api/types';
+import { ReferendumInfo, ReferendumIndex } from '@polkadot/types/index';
+
+import { drr } from '../util/drr';
+
+/**
+ * @name ReferendumInfoExtended
+ * @description
+ * A [[ReferendumInfo]] with an additional `index` field
+ */
+export class ReferendumInfoExtended extends ReferendumInfo {
+  private _index: ReferendumIndex;
+
+  constructor (info: ReferendumInfo, index: BN | number) {
+    super(info);
+
+    this._index = new ReferendumIndex(index);
+  }
+
+  /**
+   * @description Convenience getter, returns the referendumIndex
+   */
+  get index (): ReferendumIndex {
+    return this._index;
+  }
+}
+
+export function referendumInfo (api: ApiInterface$Rx) {
+  return (id: BN | number): Observable<ReferendumInfoExtended> => {
+    return (api.query.democracy.referendumInfoOf(id) as Observable<ReferendumInfo>)
+      .pipe(
+        map((info) => new ReferendumInfoExtended(info, id)),
+        drr()
+      );
+  };
+
+}

packages/api-derive/src/democracy/referendumInfos.ts

@@ -4,22 +4,19 @@
 
 import BN from 'bn.js';
 import { combineLatest, Observable, of } from 'rxjs';
-import { filter } from 'rxjs/operators';
 import { ApiInterface$Rx } from '@polkadot/api/types';
-import { ReferendumInfo } from '@polkadot/types/index';
 
 import { drr } from '../util/drr';
+import { referendumInfo, ReferendumInfoExtended } from './referendumInfo';
 
 export function referendumInfos (api: ApiInterface$Rx) {
-  return (ids: Array<BN | number> = []): Observable<Array<ReferendumInfo>> => {
+  const referendumInfoOf = referendumInfo(api);
+
+  return (ids: Array<BN | number> = []): Observable<Array<ReferendumInfoExtended>> => {
     return !ids || !ids.length
       ? of([]).pipe(drr())
       : combineLatest(
-        ids.map(
-          (id) => (api.query.democracy.referendumInfoOf(id) as Observable<ReferendumInfo>).pipe(
-            filter((info) => !!info)
-          )
-        )
+        ids.map((id) => referendumInfoOf(id))
       ).pipe(
         drr()
       );

packages/api-derive/src/democracy/referendums.ts

@@ -5,13 +5,14 @@
 import { combineLatest, Observable, of } from 'rxjs';
 import { switchMap } from 'rxjs/operators';
 import { ApiInterface$Rx } from '@polkadot/api/types';
-import { ReferendumIndex, ReferendumInfo } from '@polkadot/types/index';
+import { ReferendumIndex } from '@polkadot/types/index';
 
-import { referendumInfos } from './referendumInfos';
 import { drr } from '../util/drr';
+import { ReferendumInfoExtended } from './referendumInfo';
+import { referendumInfos } from './referendumInfos';
 
 export function referendums (api: ApiInterface$Rx) {
-  return (): Observable<Array<ReferendumInfo>> =>
+  return (): Observable<Array<ReferendumInfoExtended>> =>
     (combineLatest(
       api.query.democracy.nextTally(),
       api.query.democracy.referendumCount()