added Lindex command to node (#999)

CHANGELOG.md

@@ -15,6 +15,7 @@
 * Python: Added ECHO command ([#953](https://github.com/aws/glide-for-redis/pull/953))
 * Python: Added ZPOPMIN command ([#975](https://github.com/aws/glide-for-redis/pull/975))
 * Node: Added STRLEN command ([#993](https://github.com/aws/glide-for-redis/pull/993))
+* Node: Added LINDEX command ([#999](https://github.com/aws/glide-for-redis/pull/999))
 
 #### Features
 * Python, Node: Added support in Lua Scripts ([#775](https://github.com/aws/glide-for-redis/pull/775), [#860](https://github.com/aws/glide-for-redis/pull/860))

glide-core/src/protobuf/redis_request.proto

@@ -108,6 +108,7 @@ enum RequestType {
     Echo = 70;
     ZPopMin = 71;
     Strlen = 72;
+    Lindex = 73;
 }
 
 message Command {

glide-core/src/socket_listener.rs

@@ -351,6 +351,7 @@ fn get_command(request: &Command) -> Option<Cmd> {
         RequestType::Echo => Some(cmd("ECHO")),
         RequestType::ZPopMin => Some(cmd("ZPOPMIN")),
         RequestType::Strlen => Some(cmd("STRLEN")),
+        RequestType::Lindex => Some(cmd("LINDEX")),
     }
 }
 

node/src/BaseClient.ts

@@ -39,6 +39,7 @@ import {
     createLRange,
     createLRem,
     createLTrim,
+    createLindex,
     createMGet,
     createMSet,
     createPExpire,
@@ -1096,6 +1097,21 @@ export class BaseClient {
         preferReplica: connection_request.ReadFrom.PreferReplica,
     };
 
+    /** Returns the element at index `index` in the list stored at `key`.
+     * The index is zero-based, so 0 means the first element, 1 the second element and so on.
+     * Negative indices can be used to designate elements starting at the tail of the list.
+     * Here, -1 means the last element, -2 means the penultimate and so forth.
+     * See https://redis.io/commands/lindex/ for more details.
+     *
+     * @param key - The `key` of the list.
+     * @param index - The `index` of the element in the list to retrieve.
+     * @returns - The element at `index` in the list stored at `key`.
+     * If `index` is out of range or if `key` does not exist, null is returned.
+     */
+    public lindex(key: string, index: number): Promise<string | null> {
+        return this.createWritePromise(createLindex(key, index));
+    }
+
     /**
      * @internal
      */

node/src/Commands.ts

@@ -830,3 +830,13 @@ export function createType(key: string): redis_request.Command {
 export function createStrlen(key: string): redis_request.Command {
     return createCommand(RequestType.Strlen, [key]);
 }
+
+/**
+ * @internal
+ */
+export function createLindex(
+    key: string,
+    index: number
+): redis_request.Command {
+    return createCommand(RequestType.Lindex, [key, index.toString()]);
+}

node/src/Transaction.ts

@@ -62,6 +62,7 @@ import {
     createZcount,
     createZrem,
     createZscore,
+    createLindex,
 } from "./Commands";
 import { redis_request } from "./ProtobufMessage";
 
@@ -866,6 +867,21 @@ export class BaseTransaction<T extends BaseTransaction<T>> {
     public customCommand(args: string[]): T {
         return this.addAndReturn(createCustomCommand(args));
     }
+
+    /** Returns the element at index `index` in the list stored at `key`.
+     * The index is zero-based, so 0 means the first element, 1 the second element and so on.
+     * Negative indices can be used to designate elements starting at the tail of the list.
+     * Here, -1 means the last element, -2 means the penultimate and so forth.
+     * See https://redis.io/commands/lindex/ for more details.
+     *
+     * @param key - The `key` of the list.
+     * @param index - The `index` of the element in the list to retrieve.
+     * Command Response - The element at index in the list stored at `key`.
+     * If `index` is out of range or if `key` does not exist, null is returned.
+     */
+    public lindex(key: string, index: number): T {
+        return this.addAndReturn(createLindex(key, index));
+    }
 }
 
 /**

node/tests/SharedTests.ts

@@ -1535,6 +1535,24 @@ export function runBaseTests<Context>(config: {
         },
         config.timeout
     );
+    it.each([ProtocolVersion.RESP2, ProtocolVersion.RESP3])(
+        `lindex test_%p`,
+        async (protocol) => {
+            await runTest(async (client: BaseClient) => {
+                const listName = uuidv4();
+                const listKey1Value = uuidv4();
+                const listKey2Value = uuidv4();
+                expect(
+                    await client.lpush(listName, [listKey1Value, listKey2Value])
+                ).toEqual(2);
+                expect(await client.lindex(listName, 0)).toEqual(listKey2Value);
+                expect(await client.lindex(listName, 1)).toEqual(listKey1Value);
+                expect(await client.lindex("notExsitingList", 1)).toEqual(null);
+                expect(await client.lindex(listName, 3)).toEqual(null);
+            }, protocol);
+        },
+        config.timeout
+    );
 }
 
 export function runCommonTests<Context>(config: {

node/tests/TestUtilities.ts

@@ -115,6 +115,8 @@ export function transactionTest(
     args.push([field + "3", field + "2"]);
     baseTransaction.rpush(key6, [field + "1", field + "2", field + "3"]);
     args.push(3);
+    baseTransaction.lindex(key6, 0);
+    args.push(field + "1");
     baseTransaction.rpop(key6);
     args.push(field + "3");
     baseTransaction.rpopCount(key6, 2);