Node: added APPEND command

CHANGELOG.md

@@ -49,6 +49,7 @@
 * Node: Added ZREMRANGEBYLEX command ([#2025](https://github.com/valkey-io/valkey-glide/pull/2025))
 * Node: Added ZSCAN command ([#2061](https://github.com/valkey-io/valkey-glide/pull/2061))
 * Node: Added SETRANGE command ([#2066](https://github.com/valkey-io/valkey-glide/pull/2066))
+* Node: Added APPEND command ([#2095](https://github.com/valkey-io/valkey-glide/pull/2095))
 * Node: Added XDEL command ([#2064](https://github.com/valkey-io/valkey-glide/pull/2064))
 * Node: Added LMPOP & BLMPOP command ([#2050](https://github.com/valkey-io/valkey-glide/pull/2050))
 * Node: Added PUBSUB support ([#1964](https://github.com/valkey-io/valkey-glide/pull/1964))

node/src/BaseClient.ts

@@ -47,6 +47,7 @@ import {
     StreamReadOptions,
     StreamTrimOptions,
     ZAddOptions,
+    createAppend,
     createBLMPop,
     createBLMove,
     createBLPop,
@@ -4611,6 +4612,32 @@ export class BaseClient {
         return this.createWritePromise(createSetRange(key, offset, value));
     }
 
+    /**
+     * Appends a `value` to a `key`. If `key` does not exist it is created and set as an empty string,
+     * so `APPEND` will be similar to {@link set} in this special case.
+     *
+     * See https://valkey.io/commands/append/ for more details.
+     *
+     * @param key - The key of the string.
+     * @param value - The key of the string.
+     * @returns The length of the string after appending the value.
+     *
+     * @example
+     * ```typescript
+     * const len = await client.append("key", "Hello");
+     * console.log(len);
+     *     // Output: 5 - Indicates that "Hello" has been appended to the value of "key", which was initially
+     *     // empty, resulting in a new value of "Hello" with a length of 5 - similar to the set operation.
+     * len = await client.append("key", " world");
+     * console.log(result);
+     *     // Output: 11 - Indicates that " world" has been appended to the value of "key", resulting in a
+     *     // new value of "Hello world" with a length of 11.
+     * ```
+     */
+    public async append(key: string, value: string): Promise<number> {
+        return this.createWritePromise(createAppend(key, value));
+    }
+
     /**
      * Pops one or more elements from the first non-empty list from the provided `keys`.
      *

node/src/Commands.ts

@@ -3091,6 +3091,14 @@ export function createSetRange(
     return createCommand(RequestType.SetRange, [key, offset.toString(), value]);
 }
 
+/** @internal */
+export function createAppend(
+    key: string,
+    value: string,
+): command_request.Command {
+    return createCommand(RequestType.Append, [key, value]);
+}
+
 /**
  * @internal
  */

node/src/Transaction.ts

@@ -51,6 +51,7 @@ import {
     StreamReadOptions,
     StreamTrimOptions,
     ZAddOptions,
+    createAppend,
     createBLMPop,
     createBLMove,
     createBLPop,
@@ -2772,6 +2773,21 @@ export class BaseTransaction<T extends BaseTransaction<T>> {
         return this.addAndReturn(createSetRange(key, offset, value));
     }
 
+    /**
+     * Appends a `value` to a `key`. If `key` does not exist it is created and set as an empty string,
+     * so `APPEND` will be similar to {@link set} in this special case.
+     *
+     * See https://valkey.io/commands/append/ for more details.
+     *
+     * @param key - The key of the string.
+     * @param value - The key of the string.
+     *
+     * Command Response - The length of the string after appending the value.
+     */
+    public append(key: string, value: string): T {
+        return this.addAndReturn(createAppend(key, value));
+    }
+
     /**
      * Pops one or more elements from the first non-empty list from the provided `keys`.
      *

node/tests/SharedTests.ts

@@ -4707,6 +4707,29 @@ export function runBaseTests<Context>(config: {
         config.timeout,
     );
 
+    it.each([ProtocolVersion.RESP2, ProtocolVersion.RESP3])(
+        "append test_%p",
+        async (protocol) => {
+            await runTest(async (client: BaseClient) => {
+                const key1 = uuidv4();
+                const key2 = uuidv4();
+                const value = uuidv4();
+
+                // Append on non-existing string(similar to SET)
+                expect(await client.append(key1, value)).toBe(value.length);
+                expect(await client.append(key1, value)).toBe(value.length * 2);
+                expect(await client.get(key1)).toEqual(value.concat(value));
+
+                // key exists but holding the wrong kind of value
+                expect(await client.sadd(key2, ["a"])).toBe(1);
+                await expect(client.append(key2, "_")).rejects.toThrow(
+                    RequestError,
+                );
+            }, protocol);
+        },
+        config.timeout,
+    );
+
     // Set command tests
 
     async function setWithExpiryOptions(client: BaseClient) {

node/tests/TestUtilities.ts

@@ -534,7 +534,11 @@ export async function transactionTest(
     baseTransaction.strlen(key1);
     responseData.push(["strlen(key1)", 3]);
     baseTransaction.setrange(key1, 0, "GLIDE");
-    responseData.push(["setrange(key1, 0, 'GLIDE'", 5]);
+    responseData.push(["setrange(key1, 0, 'GLIDE')", 5]);
+    baseTransaction.del([key1]);
+    responseData.push(["del([key1])", 1]);
+    baseTransaction.append(key1, "bar");
+    responseData.push(["append(key1, value)", 3]);
     baseTransaction.del([key1]);
     responseData.push(["del([key1])", 1]);
     baseTransaction.hset(key4, { [field]: value });