fix(headers): always send lowercase headers and strip undefined (BREA…

…KING in rare cases) (#608)

BREAKING: If you previously sent `My-Header: foo` and `my-header: bar`,
both would get sent. Now, only one will.
If you previously sent `My-Header: undefined`, it would send as such.
Now, the header will not be sent.

src/core.ts

@@ -301,18 +301,7 @@ export abstract class APIClient {
  headers[this.idempotencyHeader] = options.idempotencyKey;
  }
 
- const reqHeaders: Record<string, string> = {
- ...(contentLength && { 'Content-Length': contentLength }),
- ...this.defaultHeaders(options),
- ...headers,
- };
- // let builtin fetch set the Content-Type for multipart bodies
- if (isMultipartBody(options.body) && shimsKind !== 'node') {
- delete reqHeaders['Content-Type'];
- }
-
- // Strip any headers being explicitly omitted with null
- Object.keys(reqHeaders).forEach((key) => reqHeaders[key] === null && delete reqHeaders[key]);
+ const reqHeaders = this.buildHeaders({ options, headers, contentLength });
 
  const req: RequestInit = {
  method,
@@ -324,9 +313,35 @@ export abstract class APIClient {
  signal: options.signal ?? null,
  };
 
+ return { req, url, timeout };
+ }
+
+ private buildHeaders({
+ options,
+ headers,
+ contentLength,
+ }: {
+ options: FinalRequestOptions;
+ headers: Record<string, string | null | undefined>;
+ contentLength: string | null | undefined;
+ }): Record<string, string> {
+ const reqHeaders: Record<string, string> = {};
+ if (contentLength) {
+ reqHeaders['content-length'] = contentLength;
+ }
+
+ const defaultHeaders = this.defaultHeaders(options);
+ applyHeadersMut(reqHeaders, defaultHeaders);
+ applyHeadersMut(reqHeaders, headers);
+
+ // let builtin fetch set the Content-Type for multipart bodies
+ if (isMultipartBody(options.body) && shimsKind !== 'node') {
+ delete reqHeaders['content-type'];
+ }
+
  this.validateHeaders(reqHeaders, headers);
 
- return { req, url, timeout };
+ return reqHeaders;
  }
 
  /**
@@ -1013,6 +1028,28 @@ export function hasOwn(obj: Object, key: string): boolean {
  return Object.prototype.hasOwnProperty.call(obj, key);
 }
 
+/**
+ * Copies headers from "newHeaders" onto "targetHeaders",
+ * using lower-case for all properties,
+ * ignoring any keys with undefined values,
+ * and deleting any keys with null values.
+ */
+function applyHeadersMut(targetHeaders: Headers, newHeaders: Headers): void {
+ for (const k in newHeaders) {
+ if (!hasOwn(newHeaders, k)) continue;
+ const lowerKey = k.toLowerCase();
+ if (!lowerKey) continue;
+
+ const val = newHeaders[k];
+
+ if (val === null) {
+ delete targetHeaders[lowerKey];
+ } else if (val !== undefined) {
+ targetHeaders[lowerKey] = val;
+ }
+ }
+}
+
 export function debug(action: string, ...args: any[]) {
  if (typeof process !== 'undefined' && process.env['DEBUG'] === 'true') {
  console.log(`OpenAI:DEBUG:${action}`, ...args);

tests/index.test.ts

@@ -28,25 +28,25 @@ describe('instantiate client', () => {
 
  test('they are used in the request', () => {
  const { req } = client.buildRequest({ path: '/foo', method: 'post' });
- expect((req.headers as Headers)['X-My-Default-Header']).toEqual('2');
+ expect((req.headers as Headers)['x-my-default-header']).toEqual('2');
  });
 
- test('can be overriden with `undefined`', () => {
+ test('can ignore `undefined` and leave the default', () => {
  const { req } = client.buildRequest({
  path: '/foo',
  method: 'post',
  headers: { 'X-My-Default-Header': undefined },
  });
- expect((req.headers as Headers)['X-My-Default-Header']).toBeUndefined();
+ expect((req.headers as Headers)['x-my-default-header']).toEqual('2');
  });
 
- test('can be overriden with `null`', () => {
+ test('can be removed with `null`', () => {
  const { req } = client.buildRequest({
  path: '/foo',
  method: 'post',
  headers: { 'X-My-Default-Header': null },
  });
- expect((req.headers as Headers)['X-My-Default-Header']).toBeUndefined();
+ expect(req.headers as Headers).not.toHaveProperty('x-my-default-header');
  });
  });
 
@@ -179,12 +179,27 @@ describe('request building', () => {
  describe('Content-Length', () => {
  test('handles multi-byte characters', () => {
  const { req } = client.buildRequest({ path: '/foo', method: 'post', body: { value: '—' } });
- expect((req.headers as Record<string, string>)['Content-Length']).toEqual('20');
+ expect((req.headers as Record<string, string>)['content-length']).toEqual('20');
  });
 
  test('handles standard characters', () => {
  const { req } = client.buildRequest({ path: '/foo', method: 'post', body: { value: 'hello' } });
- expect((req.headers as Record<string, string>)['Content-Length']).toEqual('22');
+ expect((req.headers as Record<string, string>)['content-length']).toEqual('22');
+ });
+ });
+
+ describe('custom headers', () => {
+ test('handles undefined', () => {
+ const { req } = client.buildRequest({
+ path: '/foo',
+ method: 'post',
+ body: { value: 'hello' },
+ headers: { 'X-Foo': 'baz', 'x-foo': 'bar', 'x-Foo': undefined, 'x-baz': 'bam', 'X-Baz': null },
+ });
+ expect((req.headers as Record<string, string>)['x-foo']).toEqual('bar');
+ expect((req.headers as Record<string, string>)['x-Foo']).toEqual(undefined);
+ expect((req.headers as Record<string, string>)['X-Foo']).toEqual(undefined);
+ expect((req.headers as Record<string, string>)['x-baz']).toEqual(undefined);
  });
  });
 });