Update drr equality (#1469)

* Update drr equality

* null === null

* Array length compare

* isFunction(next.eq)

* Just JSON.stringify on compare

* Add distinctUntilChanged in  rpc-core

* prev/next -> a/b

packages/api-derive/src/util/drr.ts

@@ -22,7 +22,9 @@ export const drr = (): DrrResult => <T> (source$: Observable<T>): Observable<T>
 
       throw error;
     }),
-    distinctUntilChanged(),
+    distinctUntilChanged((a: any, b: any): boolean =>
+      JSON.stringify({ value: a }) === JSON.stringify({ value: b })
+    ),
     publishReplay(1),
     refCount()
   );

packages/rpc-core/src/index.ts

@@ -10,7 +10,7 @@ import { RpcInterfaceMethod } from './types';
 
 import memoizee from 'memoizee';
 import { combineLatest, from, Observable, Observer, of, throwError } from 'rxjs';
-import { catchError, map, publishReplay, refCount, switchMap } from 'rxjs/operators';
+import { catchError, distinctUntilChanged, map, publishReplay, refCount, switchMap } from 'rxjs/operators';
 import interfaces from '@polkadot/jsonrpc';
 import { Option, StorageKey, Vec, createClass } from '@polkadot/types';
 import { createTypeUnsafe } from '@polkadot/types/codec';
@@ -250,6 +250,10 @@ export default class Rpc implements RpcInterface {
             );
         };
       }).pipe(
+        // Duplicated in api-derive/util/drr
+        distinctUntilChanged((a: any, b: any): boolean =>
+          JSON.stringify({ value: a }) === JSON.stringify({ value: b })
+        ),
         publishReplay(1),
         refCount()
       );