feat: support multipart/related requests (#610)

* feat: support multipart/related requests

* move uuid to deps

* fix typo

* add spec note

package.json

@@ -82,14 +82,14 @@
     "tmp": "0.2.3",
     "ts-loader": "^8.0.0",
     "typescript": "^5.1.6",
-    "uuid": "^9.0.0",
     "webpack": "^5.35.0",
     "webpack-cli": "^4.0.0"
   },
   "dependencies": {
     "extend": "^3.0.2",
     "https-proxy-agent": "^7.0.1",
     "is-stream": "^2.0.0",
-    "node-fetch": "^2.6.9"
+    "node-fetch": "^2.6.9",
+    "uuid": "^9.0.1"
   }
 }

src/common.ts

@@ -16,6 +16,7 @@ import {URL} from 'url';
 
 import {pkg} from './util';
 import extend from 'extend';
+import {Readable} from 'stream';
 
 /**
  * Support `instanceof` operator for `GaxiosError`s in different versions of this library.
@@ -135,6 +136,11 @@ export interface GaxiosResponse<T = any> {
   request: GaxiosXMLHttpRequest;
 }
 
+export interface GaxiosMultipartOptions {
+  headers: Headers;
+  content: string | Readable;
+}
+
 /**
  * Request options that are used to form the request.
  */
@@ -175,6 +181,7 @@ export interface GaxiosOptions {
    */
   maxRedirects?: number;
   follow?: number;
+  multipart?: GaxiosMultipartOptions[];
   params?: any;
   paramsSerializer?: (params: {[index: string]: string | number}) => string;
   timeout?: number;

src/gaxios.ts

@@ -21,6 +21,7 @@ import {URL} from 'url';
 
 import {
   FetchResponse,
+  GaxiosMultipartOptions,
   GaxiosError,
   GaxiosOptions,
   GaxiosPromise,
@@ -29,8 +30,9 @@ import {
   defaultErrorRedactor,
 } from './common';
 import {getRetryConfig} from './retry';
-import {Stream} from 'stream';
+import {PassThrough, Stream, pipeline} from 'stream';
 import {HttpsProxyAgent as httpsProxyAgent} from 'https-proxy-agent';
+import {v4} from 'uuid';
 
 /* eslint-disable @typescript-eslint/no-explicit-any */
 
@@ -261,7 +263,7 @@ export class Gaxios {
     }
 
     opts.headers = opts.headers || {};
-    if (opts.data) {
+    if (opts.multipart === undefined && opts.data) {
       const isFormData =
         typeof FormData === 'undefined'
           ? false
@@ -294,6 +296,19 @@ export class Gaxios {
       } else {
         opts.body = opts.data;
       }
+    } else if (opts.multipart && opts.multipart.length > 0) {
+      // note: once the minimum version reaches Node 16,
+      // this can be replaced with randomUUID() function from crypto
+      // and the dependency on UUID removed
+      const boundary = v4();
+      opts.headers['Content-Type'] = `multipart/related; boundary=${boundary}`;
+      const bodyStream = new PassThrough();
+      opts.body = bodyStream;
+      pipeline(
+        this.getMultipartRequest(opts.multipart, boundary),
+        bodyStream,
+        () => {}
+      );
     }
 
     opts.validateStatus = opts.validateStatus || this.validateStatus;
@@ -416,4 +431,32 @@ export class Gaxios {
       return response.blob();
     }
   }
+
+  /**
+   * Creates an async generator that yields the pieces of a multipart/related request body.
+   * This implementation follows the spec: https://www.ietf.org/rfc/rfc2387.txt. However, recursive
+   * multipart/related requests are not currently supported.
+   *
+   * @param {GaxioMultipartOptions[]} multipartOptions the pieces to turn into a multipart/related body.
+   * @param {string} boundary the boundary string to be placed between each part.
+   */
+  private async *getMultipartRequest(
+    multipartOptions: GaxiosMultipartOptions[],
+    boundary: string
+  ) {
+    const finale = `--${boundary}--`;
+    for (const currentPart of multipartOptions) {
+      const partContentType =
+        currentPart.headers['Content-Type'] || 'application/octet-stream';
+      const preamble = `--${boundary}\r\nContent-Type: ${partContentType}\r\n\r\n`;
+      yield preamble;
+      if (typeof currentPart.content === 'string') {
+        yield currentPart.content;
+      } else {
+        yield* currentPart.content;
+      }
+      yield '\r\n';
+    }
+    yield finale;
+  }
 }

test/test.getch.ts

@@ -14,7 +14,7 @@
 import assert from 'assert';
 import nock from 'nock';
 import sinon from 'sinon';
-import stream from 'stream';
+import stream, {Readable} from 'stream';
 import {describe, it, afterEach} from 'mocha';
 import fetch from 'node-fetch';
 import {HttpsProxyAgent} from 'https-proxy-agent';
@@ -698,6 +698,69 @@ describe('🎏 data handling', () => {
     assert.notEqual(res.data, body);
   });
 
+  it('should handle multipart/related when options.multipart is set and a single part', async () => {
+    const bodyContent = {hello: '🌎'};
+    const body = new Readable();
+    body.push(JSON.stringify(bodyContent));
+    body.push(null);
+    const scope = nock(url)
+      .matchHeader(
+        'Content-Type',
+        /multipart\/related; boundary=[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/
+      )
+      .post(
+        '/',
+        /^(--[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}[\r\n]+Content-Type: application\/json[\r\n\r\n]+{"hello":"🌎"}[\r\n]+--[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}--)$/
+      )
+      .reply(200, {});
+    const res = await request({
+      url,
+      method: 'POST',
+      multipart: [
+        {
+          headers: {'Content-Type': 'application/json'},
+          content: body,
+        },
+      ],
+    });
+    scope.done();
+    assert.ok(res.data);
+  });
+
+  it('should handle multipart/related when options.multipart is set and a multiple parts', async () => {
+    const jsonContent = {hello: '🌎'};
+    const textContent = 'hello world';
+    const body = new Readable();
+    body.push(JSON.stringify(jsonContent));
+    body.push(null);
+    const scope = nock(url)
+      .matchHeader(
+        'Content-Type',
+        /multipart\/related; boundary=[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/
+      )
+      .post(
+        '/',
+        /^(--[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}[\r\n]+Content-Type: application\/json[\r\n\r\n]+{"hello":"🌎"}[\r\n]+--[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}[\r\n]+Content-Type: text\/plain[\r\n\r\n]+hello world[\r\n]+--[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}--)$/
+      )
+      .reply(200, {});
+    const res = await request({
+      url,
+      method: 'POST',
+      multipart: [
+        {
+          headers: {'Content-Type': 'application/json'},
+          content: body,
+        },
+        {
+          headers: {'Content-Type': 'text/plain'},
+          content: textContent,
+        },
+      ],
+    });
+    scope.done();
+    assert.ok(res.data);
+  });
+
   it('should redact sensitive props via the `errorRedactor` by default', async () => {
     const REDACT =
       '<<REDACTED> - See `errorRedactor` option in `gaxios` for configuration>.';