Support the NOVALUES option of HSCAN

Issue #2705

The NOVALUES option instructs HSCAN to only return keys, without their
values.

Author: gerzse

Diff for: packages/client/lib/client/index.spec.ts

@@ -8,6 +8,7 @@ import { defineScript } from '../lua-script';
 import { spy } from 'sinon';
 import { once } from 'events';
 import { ClientKillFilters } from '../commands/CLIENT_KILL';
+import { HScanTuple } from "../commands/HSCAN";
 import { promisify } from 'util';
 
 import {version} from '../../package.json';
@@ -774,18 +775,33 @@ describe('Client', () => {
 
     testUtils.testWithClient('hScanIterator', async client => {
         const hash: Record<string, string> = {};
+        const expectedKeys: Array<string> = [];
         for (let i = 0; i < 100; i++) {
             hash[i.toString()] = i.toString();
+            expectedKeys.push(i.toString());
         }
 
         await client.hSet('key', hash);
 
         const results: Record<string, string> = {};
-        for await (const { field, value } of client.hScanIterator('key')) {
-            results[field] = value;
+        for await (const entry of client.hScanIterator('key')) {
+            const {field: field, value: value} = entry as HScanTuple;
+            results[field as string] = value as string;
         }
 
         assert.deepEqual(hash, results);
+
+        const keys: Array<string> = [];
+        for await (const entry of client.hScanIterator('key', { NOVALUES: true })) {
+            const key = entry as string;
+            keys.push(key);
+        }
+
+        function sort(a: string, b: string) {
+            return Number(b) - Number(a);
+        }
+
+        assert.deepEqual(keys.sort(sort), expectedKeys.sort(sort));
     }, GLOBAL.SERVERS.OPEN);
 
     testUtils.testWithClient('sScanIterator', async client => {

Diff for: packages/client/lib/client/index.ts

@@ -1,5 +1,5 @@
 import COMMANDS from './commands';
-import { RedisCommand, RedisCommandArguments, RedisCommandRawReply, RedisCommandReply, RedisFunctions, RedisModules, RedisExtensions, RedisScript, RedisScripts, RedisCommandSignature, ConvertArgumentType, RedisFunction, ExcludeMappedString, RedisCommands } from '../commands';
+import { RedisCommand, RedisCommandArguments, RedisCommandRawReply, RedisCommandReply, RedisFunctions, RedisModules, RedisExtensions, RedisScript, RedisScripts, RedisCommandSignature, ConvertArgumentType, RedisFunction, ExcludeMappedString, RedisCommands, RedisCommandArgument } from '../commands';
 import RedisSocket, { RedisSocketOptions, RedisTlsSocketOptions } from './socket';
 import RedisCommandsQueue, { QueueCommandOptions } from './commands-queue';
 import RedisClientMultiCommand, { RedisClientMultiCommandType } from './multi-command';
@@ -809,13 +809,19 @@ export default class RedisClient<
         } while (cursor !== 0);
     }
 
-    async* hScanIterator(key: string, options?: ScanOptions): AsyncIterable<ConvertArgumentType<HScanTuple, string>> {
+    async* hScanIterator(key: string, options?: ScanOptions): AsyncIterable<ConvertArgumentType<HScanTuple | RedisCommandArgument, string>> {
         let cursor = 0;
         do {
             const reply = await (this as any).hScan(key, cursor, options);
             cursor = reply.cursor;
-            for (const tuple of reply.tuples) {
-                yield tuple;
+            if (options?.NOVALUES === true) {
+                for (const k of reply.keys) {
+                    yield k;
+                }
+            } else {
+                for (const tuple of reply.tuples) {
+                    yield tuple;
+                }
             }
         } while (cursor !== 0);
     }

Diff for: packages/client/lib/commands/HSCAN.spec.ts

@@ -1,6 +1,7 @@
 import { strict as assert } from 'assert';
 import testUtils, { GLOBAL } from '../test-utils';
 import { transformArguments, transformReply } from './HSCAN';
+import { RedisCommandArguments } from "./index";
 
 describe('HSCAN', () => {
     describe('transformArguments', () => {
@@ -29,6 +30,18 @@ describe('HSCAN', () => {
             );
         });
 
+        it('with NOVALUES', () => {
+            const expectedReply: RedisCommandArguments = ['HSCAN', 'key', '0', 'NOVALUES'];
+            expectedReply.preserve = true;
+
+            assert.deepEqual(
+                transformArguments('key', 0, {
+                    NOVALUES: true
+                }),
+                expectedReply
+            );
+        });
+
         it('with MATCH & COUNT', () => {
             assert.deepEqual(
                 transformArguments('key', 0, {
@@ -38,6 +51,20 @@ describe('HSCAN', () => {
                 ['HSCAN', 'key', '0', 'MATCH', 'pattern', 'COUNT', '1']
             );
         });
+
+        it('with MATCH & COUNT & NOVALUES', () => {
+            const expectedReply: RedisCommandArguments = ['HSCAN', 'key', '0', 'MATCH', 'pattern', 'COUNT', '1', 'NOVALUES'];
+            expectedReply.preserve = true;
+
+            assert.deepEqual(
+                transformArguments('key', 0, {
+                    MATCH: 'pattern',
+                    COUNT: 1,
+                    NOVALUES: true
+                }),
+                expectedReply
+            );
+        });
     });
 
     describe('transformReply', () => {
@@ -51,6 +78,16 @@ describe('HSCAN', () => {
             );
         });
 
+        it('without keys', () => {
+            assert.deepEqual(
+                transformReply(['0', []], true),
+                {
+                    cursor: 0,
+                    keys: []
+                }
+            );
+        });
+
         it('with tuples', () => {
             assert.deepEqual(
                 transformReply(['0', ['field', 'value']]),
@@ -63,6 +100,16 @@ describe('HSCAN', () => {
                 }
             );
         });
+
+        it('with keys', () => {
+            assert.deepEqual(
+                transformReply(['0', ['key1', 'key2']], true),
+                {
+                    cursor: 0,
+                    keys: ['key1', 'key2']
+                }
+            );
+        });
     });
 
     testUtils.testWithClient('client.hScan', async client => {
@@ -73,5 +120,34 @@ describe('HSCAN', () => {
                 tuples: []
             }
         );
+
+        assert.deepEqual(
+            await client.hScan('key', 0, { NOVALUES: true }),
+            {
+                cursor: 0,
+                keys: []
+            }
+        );
+
+        await Promise.all([
+            client.hSet('key', 'a', '1'),
+            client.hSet('key', 'b', '2')
+        ]);
+
+        assert.deepEqual(
+            await client.hScan('key', 0),
+            {
+                cursor: 0,
+                tuples: [{field: 'a', value: '1'}, {field: 'b', value: '2'}]
+            }
+        );
+
+        assert.deepEqual(
+            await client.hScan('key', 0, { NOVALUES: true }),
+            {
+                cursor: 0,
+                keys: ['a', 'b']
+            }
+        );
     }, GLOBAL.SERVERS.OPEN);
 });

Diff for: packages/client/lib/commands/HSCAN.ts

@@ -25,20 +25,27 @@ export interface HScanTuple {
 
 interface HScanReply {
     cursor: number;
-    tuples: Array<HScanTuple>;
+    tuples?: Array<HScanTuple>;
+    keys?: Array<RedisCommandArgument>;
 }
 
-export function transformReply([cursor, rawTuples]: HScanRawReply): HScanReply {
-    const parsedTuples = [];
-    for (let i = 0; i < rawTuples.length; i += 2) {
-        parsedTuples.push({
-            field: rawTuples[i],
-            value: rawTuples[i + 1]
-        });
+export function transformReply([cursor, rawData]: HScanRawReply, noValues?: boolean): HScanReply {
+    if (noValues === true) {
+        return {
+            cursor: Number(cursor),
+            keys: [...rawData]
+        };
+    } else {
+        const parsedTuples = [];
+        for (let i = 0; i < rawData.length; i += 2) {
+            parsedTuples.push({
+                field: rawData[i],
+                value: rawData[i + 1]
+            });
+        }
+        return {
+            cursor: Number(cursor),
+            tuples: parsedTuples
+        };
     }
-
-    return {
-        cursor: Number(cursor),
-        tuples: parsedTuples
-    };
 }

Diff for: packages/client/lib/commands/generic-transformers.ts

@@ -13,6 +13,7 @@ export type BitValue = 0 | 1;
 export interface ScanOptions {
     MATCH?: string;
     COUNT?: number;
+    NOVALUES?: boolean;
 }
 
 export function pushScanArguments(
@@ -30,6 +31,11 @@ export function pushScanArguments(
         args.push('COUNT', options.COUNT.toString());
     }
 
+    if (options?.NOVALUES === true) {
+        args.push('NOVALUES');
+        args.preserve = true;
+    }
+
     return args;
 }