feat: allow baseUrl override

Author: ajaishankar

.eslintignore

@@ -1,2 +1,3 @@
 test/examples/*.ts
-dist
+dist
+build.js

README.md

@@ -36,8 +36,6 @@ npx openapi-typescript https://petstore.swagger.io/v2/swagger.json --output pets
 **Typed fetch client**
 
 ```ts
-import 'whatwg-fetch'
-
 import { Fetcher } from 'openapi-typescript-fetch'
 
 import { paths } from './petstore'
@@ -125,30 +123,6 @@ fetcher.configure({
 fetcher.use(logger)
 ```
 
-### Server Side Usage
-
-This library can be used server side with [node-fetch](https://www.npmjs.com/package/node-fetch)
-
-Node CommonJS setup
-```ts
-// install node-fetch v2
-npm install node-fetch@2
-npm install @types/node-fetch@2
-
-// fetch-polyfill.ts
-import fetch, { Headers, Request, Response } from 'node-fetch'
-
-if (!globalThis.fetch) {
-    globalThis.fetch = fetch as any
-    globalThis.Headers = Headers as any
-    globalThis.Request = Request as any
-    globalThis.Response = Response as any
-}
-
-// index.ts
-import './fetch-polyfill'
-```
-
 ### Utility Types
 
 - `OpArgType` - Infer argument type of an operation
@@ -190,4 +164,23 @@ const body = arrayRequestBody([{ item: 1}], { param: 2})
 // body type is { item: number }[] & { param: number }
 ```
 
+### Changing the baseUrl at runtime
+
+The baseUrl can be configured with a function that returns the url at runtime
+
+```ts
+fetcher.configure({
+  baseUrl: () => getBaseUrl(...)
+})
+```
+
+It can also be overriden per method invocation
+
+```ts
+await findPetsByStatus(
+  { status: ['available', 'pending'] },
+  { baseUrl: "https://staging.petstore.swagger.io/v2" }
+)
+```
+
 Happy fetching! 👍

src/fetcher.ts

@@ -183,6 +183,7 @@ function wrapMiddlewares(middlewares: Middleware[], fetch: Fetch): Fetch {
       return fetch(url, init)
     }
     const current = middlewares[index]
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     return await current!(url, init, (nextUrl, nextInit) =>
       handler(index + 1, nextUrl, nextInit),
     )
@@ -228,7 +229,7 @@ function createFetch<OP>(fetch: _TypedFetch<OP>): TypedFetch<OP> {
 }
 
 function fetcher<Paths>() {
-  let baseUrl = ''
+  let baseUrl = '' as string | (() => string)
   let defaultInit: RequestInit = {}
   const middlewares: Middleware[] = []
   const fetch = wrapMiddlewares(middlewares, fetchJson)
@@ -246,15 +247,17 @@ function fetcher<Paths>() {
         create: ((queryParams?: Record<string, true | 1>) =>
           createFetch((payload, init) =>
             fetchUrl({
-              baseUrl: baseUrl || '',
+              baseUrl:
+                init?.baseUrl ??
+                (typeof baseUrl === 'function' ? baseUrl() : baseUrl),
               path: path as string,
               method: method as Method,
               queryParams: Object.keys(queryParams || {}),
               payload,
               init: mergeRequestInit(defaultInit, init),
               fetch,
             }),
-          )) as CreateFetch<M, Paths[P][M]>,
+          )) as unknown as CreateFetch<M, Paths[P][M]>,
       }),
     }),
   }

src/types.ts

@@ -92,7 +92,7 @@ export type Fetch = (
 
 export type _TypedFetch<OP> = (
   arg: OpArgType<OP>,
-  init?: RequestInit,
+  init?: RequestInit & { baseUrl?: string },
 ) => Promise<ApiResponse<OpReturnType<OP>>>
 
 export type TypedFetch<OP> = _TypedFetch<OP> & {
@@ -130,7 +130,7 @@ export type Middleware = (
 ) => Promise<ApiResponse>
 
 export type FetchConfig = {
-  baseUrl?: string
+  baseUrl?: string | (() => string)
   init?: RequestInit
   use?: Middleware[]
 }

test/fetch.test.ts

@@ -231,6 +231,32 @@ describe('fetch', () => {
     expect(data.headers).toEqual({ ...expectedHeaders, admin: 'true' })
   })
 
+  describe('baseUrl', () => {
+    const baseUrl = 'https://api2.backend.dev'
+    const payload = {
+      a: 1,
+      b: '2',
+      scalar: 'a',
+      list: ['b', 'c'],
+    }
+
+    it('can override baseUrl per invocation', async () => {
+      fetcher.configure({}) // empty baseUrl
+      const fun = fetcher.path('/query/{a}/{b}').method('get').create()
+      const { data } = await fun(payload, { baseUrl })
+      expect(data.host).toBe('api2.backend.dev')
+    })
+
+    it('can configure with a function', async () => {
+      fetcher.configure({
+        baseUrl: () => baseUrl,
+      })
+      const fun = fetcher.path('/query/{a}/{b}').method('get').create()
+      const { data } = await fun(payload)
+      expect(data.host).toBe('api2.backend.dev')
+    })
+  })
+
   it('middleware', async () => {
     const fun = fetcher
       .path('/bodyquery/{id}')

test/mocks/handlers.ts

@@ -36,10 +36,30 @@ function getResult(
   )
 }
 
+function getResultWithHost(
+  req: RestRequest,
+  res: ResponseComposition,
+  ctx: RestContext,
+) {
+  return res(
+    ctx.json({
+      params: req.params,
+      headers: getHeaders(req),
+      query: getQuery(req),
+      body: req.body,
+      host: new URL(req.url).host,
+    }),
+  )
+}
+
 const HOST = 'https://api.backend.dev'
+const HOST2 = 'https://api2.backend.dev'
 
 const methods = {
-  withQuery: [rest.get(`${HOST}/query/:a/:b`, getResult)],
+  withQuery: [
+    rest.get(`${HOST}/query/:a/:b`, getResult),
+    rest.get(`${HOST2}/query/:a/:b`, getResultWithHost),
+  ],
   withBody: ['post', 'put', 'patch', 'delete'].map((method) => {
     return (rest as any)[method](`${HOST}/body/:id`, getResult)
   }),

test/paths.ts

@@ -4,6 +4,7 @@ export type Data = {
   headers: Record<string, string>
   query: Record<string, string | string[]>
   body: any
+  host?: string
 }
 
 type Query = {