From a7f8b011cf61716aec30b6ee75bc5b3b6c9b89d6 Mon Sep 17 00:00:00 2001
From: Xueying Wang <wang.xy.326@gmail.com>
Date: Mon, 29 Jan 2024 14:48:13 +0100
Subject: [PATCH] fix api-derive subscribeFinalizedBlocks

only emits latest block from the block range
---
 packages/api-derive/src/chain/subscribeFinalizedBlocks.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/api-derive/src/chain/subscribeFinalizedBlocks.ts b/packages/api-derive/src/chain/subscribeFinalizedBlocks.ts
index 426d363a3573..e8c24210e461 100644
--- a/packages/api-derive/src/chain/subscribeFinalizedBlocks.ts
+++ b/packages/api-derive/src/chain/subscribeFinalizedBlocks.ts
@@ -5,7 +5,7 @@ import type { Observable } from 'rxjs';
 import type { SignedBlockExtended } from '../type/types.js';
 import type { DeriveApi } from '../types.js';
 
-import { switchMap } from 'rxjs';
+import { concatMap } from 'rxjs';
 
 import { memo } from '../util/index.js';
 
@@ -16,7 +16,7 @@ import { memo } from '../util/index.js';
 export function subscribeFinalizedBlocks (instanceId: string, api: DeriveApi): () => Observable<SignedBlockExtended> {
   return memo(instanceId, (): Observable<SignedBlockExtended> =>
     api.derive.chain.subscribeFinalizedHeads().pipe(
-      switchMap((header) =>
+      concatMap((header) =>
         api.derive.chain.getBlock(header.createdAtHash || header.hash)
       )
     )