feat(Requests): add attachment keys and form data for stickers

Ported from discordjs/discord.js#5867

Co-authored-by: Advaith <advaithj1@gmail.com>

packages/rest/__tests__/REST.test.ts

@@ -36,7 +36,7 @@ nock(`${DefaultRestOptions.api}/v${DefaultRestOptions.version}`)
 	.post('/postEcho')
 	.reply(200, (_, body) => body)
 	.post('/postAttachment')
-	.times(3)
+	.times(4)
 	.reply(200, (_, body) => ({
 		body: body
 			.replace(/\r\n/g, '\n')
@@ -143,6 +143,26 @@ test('postAttachment attachment and JSON', async () => {
 	});
 });
 
+test('postAttachment sticker and JSON', async () => {
+	expect(
+		await api.post('/postAttachment', {
+			attachments: [{ key: 'file', fileName: 'sticker.png', rawBuffer: Buffer.from('Sticker') }],
+			body: { foo: 'bar' },
+			dontUsePayloadJSON: true,
+		}),
+	).toStrictEqual({
+		body: [
+			'Content-Disposition: form-data; name="file"; filename="sticker.png"',
+			'Content-Type: image/png',
+			'',
+			'Sticker',
+			'Content-Disposition: form-data; name="foo"',
+			'',
+			'bar',
+		].join('\n'),
+	});
+});
+
 test('postEcho', async () => {
 	expect(await api.post('/postEcho', { body: { foo: 'bar' } })).toStrictEqual({ foo: 'bar' });
 });

packages/rest/src/lib/RequestManager.ts

@@ -16,6 +16,7 @@ const agent = new Agent({ keepAlive: true });
  */
 export interface RawAttachment {
 	fileName: string;
+	key?: string;
 	rawBuffer: Buffer;
 }
 
@@ -41,6 +42,10 @@ export interface RequestData {
 	 * The body to send to this request
 	 */
 	body?: unknown;
+	/**
+	 * Whether to append JSON data to form data isntead of `payload_json` when sending attachments
+	 */
+	dontUsePayloadJSON?: boolean;
 	/**
 	 * Additional headers to add to this request
 	 */
@@ -239,13 +244,17 @@ export class RequestManager extends EventEmitter {
 
 			// Attach all files to the request
 			for (const attachment of request.attachments) {
-				formData.append(attachment.fileName, attachment.rawBuffer, attachment.fileName);
+				formData.append(attachment.key ?? attachment.fileName, attachment.rawBuffer, attachment.fileName);
 			}
 
-			// If a JSON body was added as well, attach it to the form data
+			// If a JSON body was added as well, attach it to the form data, using payload_json unless otherwise specified
 			// eslint-disable-next-line no-eq-null
 			if (request.body != null) {
-				formData.append('payload_json', JSON.stringify(request.body));
+				if (request.dontUsePayloadJSON) {
+					for (const [key, value] of Object.entries(request.body as any)) formData.append(key, value);
+				} else {
+					formData.append('payload_json', JSON.stringify(request.body));
+				}
 			}
 
 			// Set the final body to the form data