feat(web-api): include a blocks argument for file uploads

docs/content/packages/web-api.md

@@ -501,6 +501,9 @@ of binary data follow soon!
 The `channel_id` and `initial_comment` aren't required, but the file either won't be shared to a channel or it won't be
 posted with a message if these aren't included.
 
+A posted message can be formatted with [Block Kit](https://docs.slack.dev/block-kit) using the `blocks` argument instead
+of the `initial_comment` text.
+
 In a successful response, the `result.files` contains an array of [shared files](https://api.slack.com/types/file).
 These files are "private" and available to just the `token` holder if no `channel_id` is included in the request, and
 are marked "public" when shared to a provided `channel_id`.

packages/web-api/src/WebClient.spec.ts

@@ -1228,6 +1228,58 @@ describe('WebClient', () => {
       uploader.done();
     });
 
+    it('uploads content', async () => {
+      const scope = nock('https://slack.com')
+        .post('/api/files.getUploadURLExternal', { filename: 'content.txt', length: 42 })
+        .reply(200, {
+          ok: true,
+          file_id: 'F0101010101',
+          upload_url: 'https://files.slack.com/upload/v1/abcdefghijklmnopqrstuvwxyz',
+        })
+        .post('/api/files.completeUploadExternal', {
+          blocks: '[{"type":"section","text":{"type":"plain_text","text":"Hello"}}]',
+          channel_id: 'C010101010',
+          files: '[{"id":"F0101010101","title":"content.txt"}]',
+        })
+        .reply(200, {
+          ok: true,
+          files: [
+            {
+              id: 'F0101010101',
+              name: 'content.txt',
+              permalink: 'https://my-workspace.slack.com/files/U0123456789/F0101010101/content.txt',
+            },
+          ],
+        });
+      const uploader = nock('https://files.slack.com').post('/upload/v1/abcdefghijklmnopqrstuvwxyz').reply(200);
+      const client = new WebClient(token);
+      const response = await client.filesUploadV2({
+        blocks: [{ type: 'section', text: { type: 'plain_text', text: 'Hello' } }],
+        channel_id: 'C010101010',
+        content: 'Words from another variable might go here!',
+        filename: 'content.txt',
+      });
+      const expected = {
+        ok: true,
+        files: [
+          {
+            ok: true,
+            files: [
+              {
+                id: 'F0101010101',
+                name: 'content.txt',
+                permalink: 'https://my-workspace.slack.com/files/U0123456789/F0101010101/content.txt',
+              },
+            ],
+            response_metadata: {},
+          },
+        ],
+      };
+      assert.deepEqual(response, expected);
+      scope.done();
+      uploader.done();
+    });
+
     it('uploads multiple files', async () => {
       const scope = nock('https://slack.com')
         .post('/api/files.getUploadURLExternal', { filename: 'test-png.png', length: 55292 })

packages/web-api/src/file-upload.ts

@@ -27,6 +27,7 @@ export async function getFileUploadJob(
   const fileUploadJob: Record<string, unknown> = {
     // supplied by user
     alt_text: options.alt_text,
+    blocks: options.blocks,
     channel_id: options.channels ?? options.channel_id,
     filename: options.filename ?? fileName,
     initial_comment: options.initial_comment,
@@ -96,8 +97,8 @@ export async function getMultipleFileUploadJobs(
         // ensure no omitted properties included in files_upload entry
         // these properties are valid only at the top-level, not
         // inside file_uploads.
-        const { channel_id, channels, initial_comment, thread_ts } = upload as FileUploadV2;
-        if (channel_id || channels || initial_comment || thread_ts) {
+        const { blocks, channel_id, channels, initial_comment, thread_ts } = upload as FileUploadV2;
+        if (blocks || channel_id || channels || initial_comment || thread_ts) {
           throw errorWithCode(
             new Error(buildInvalidFilesUploadParamError()),
             ErrorCode.FileUploadInvalidArgumentsError,
@@ -107,6 +108,7 @@ export async function getMultipleFileUploadJobs(
         // supplied at the top level.
         const uploadJobArgs: Record<string, unknown> = {
           ...upload,
+          blocks: options.blocks,
           channels: options.channels,
           channel_id: options.channel_id,
           initial_comment: options.initial_comment,
@@ -220,7 +222,7 @@ export async function getFileDataAsStream(readable: Readable): Promise<Buffer> {
 
 /**
  * Filters through all fileUploads and groups them into jobs for completion
- * based on combination of channel_id, thread_ts, initial_comment.
+ * based on combination of channel_id, thread_ts, initial_comment, blocks.
  * {@link https://api.slack.com/methods/files.completeUploadExternal files.completeUploadExternal} allows for multiple
  * files to be uploaded with a message (`initial_comment`), and as a threaded message (`thread_ts`)
  * In order to be grouped together, file uploads must have like properties.
@@ -232,13 +234,14 @@ export function getAllFileUploadsToComplete(
 ): Record<string, FilesCompleteUploadExternalArguments> {
   const toComplete: Record<string, FilesCompleteUploadExternalArguments> = {};
   for (const upload of fileUploads) {
-    const { channel_id, thread_ts, initial_comment, file_id, title } = upload;
+    const { blocks, channel_id, thread_ts, initial_comment, file_id, title } = upload;
     if (file_id) {
-      const compareString = `:::${channel_id}:::${thread_ts}:::${initial_comment}`;
+      const compareString = `:::${channel_id}:::${thread_ts}:::${initial_comment}:::${JSON.stringify(blocks)}`;
       if (!Object.prototype.hasOwnProperty.call(toComplete, compareString)) {
         toComplete[compareString] = {
           files: [{ id: file_id, title }],
           channel_id,
+          blocks,
           initial_comment,
         };
         if (thread_ts && channel_id) {
@@ -425,7 +428,7 @@ export function buildMultipleChannelsErrorMsg(): string {
 
 export function buildInvalidFilesUploadParamError(): string {
   return (
-    'You may supply file_uploads only for a single channel, comment, thread respectively. ' +
-    'Therefore, please supply any channel_id, initial_comment, thread_ts in the top-layer.'
+    'You may supply file_uploads only for a single channel, message, or thread respectively. ' +
+    'Therefore, please supply any channel_id, initial_comment or blocks, or thread_ts in the top-layer.'
   );
 }

packages/web-api/src/types/request/files.ts

@@ -1,4 +1,5 @@
 import type { Stream } from 'node:stream';
+import type { Block, KnownBlock } from '@slack/types';
 import type { ExcludeFromUnion } from '../helpers';
 import type { FilesGetUploadURLExternalResponse } from '../response/index';
 import type {
@@ -64,10 +65,19 @@ type FileDestinationArgumentChannels = FileChannelDestinationArgumentChannels |
 // https://api.slack.com/methods/files.completeUploadExternal
 export type FilesCompleteUploadExternalArguments = FileDestinationArgument &
   TokenOverridable & {
-    /** @description Array of file IDs and their corresponding (optional) titles. */
+    /**
+     * @description Array of file IDs and their corresponding (optional) titles.
+     * @example [{"id":"F044GKUHN9Z", "title":"slack-test"}]
+     **/
     files: [FileUploadComplete, ...FileUploadComplete[]];
     /** @description The message text introducing the file in the specified channel. */
     initial_comment?: string;
+    /**
+     * @description An array of structured rich text blocks. If the `initial_comment` field is provided, the `blocks` field is ignored.
+     * @example [{"type": "section", "text": {"type": "plain_text", "text": "Hello world"}}]
+     * @see {@link https://api.slack.com/reference/block-kit/blocks}
+     */
+    blocks?: (KnownBlock | Block)[];
   };
 
 // https://api.slack.com/methods/files.delete
@@ -148,6 +158,12 @@ export type FilesUploadArguments = FileUpload & TokenOverridable;
 export type FileUploadV2 = FileUpload & {
   /** @description Description of image for screen-reader. */
   alt_text?: string;
+  /**
+   * @description An array of structured rich text blocks. If the `initial_comment` field is provided, the `blocks` field is ignored.
+   * @example [{"type": "section", "text": {"type": "plain_text", "text": "Hello world"}}]
+   * @see {@link https://api.slack.com/reference/block-kit/blocks}
+   */
+  blocks?: (KnownBlock | Block)[];
   /** @description Channel ID where the file will be shared. If not specified the file will be private. */
   channel_id?: string;
   /** @deprecated use channel_id instead */
@@ -157,7 +173,10 @@ export type FileUploadV2 = FileUpload & {
 };
 
 export interface FilesUploadV2ArgumentsMultipleFiles {
-  file_uploads: ExcludeFromUnion<FileUploadV2, 'channel_id' | 'channels' | 'initial_comment' | 'thread_ts'>[];
+  file_uploads: ExcludeFromUnion<
+    FileUploadV2,
+    'blocks' | 'channel_id' | 'channels' | 'initial_comment' | 'thread_ts'
+  >[];
 }
 
 // https://tools.slack.dev/node-slack-sdk/web-api#upload-a-file