feat: Custom fetch per call

docs/astro.config.js

@@ -1,7 +1,7 @@
-import { defineConfig } from "astro/config";
 import preact from "@astrojs/preact";
 import react from "@astrojs/react";
 import sitemap from "@astrojs/sitemap";
+import { defineConfig } from "astro/config";
 import sassDts from "vite-plugin-sass-dts";
 
 // https://astro.build/config
@@ -21,9 +21,15 @@ export default defineConfig({
       },
     },
     define: {
-      "import.meta.env.VITE_ALGOLIA_APP_ID": JSON.stringify(process.env.ALGOLIA_APP_ID ?? ""),
-      "import.meta.env.VITE_ALGOLIA_INDEX_NAME": JSON.stringify(process.env.ALGOLIA_INDEX_NAME ?? ""),
-      "import.meta.env.VITE_ALGOLIA_SEARCH_KEY": JSON.stringify(process.env.ALGOLIA_SEARCH_KEY ?? ""),
+      "import.meta.env.VITE_ALGOLIA_APP_ID": JSON.stringify(
+        process.env.ALGOLIA_APP_ID ?? "",
+      ),
+      "import.meta.env.VITE_ALGOLIA_INDEX_NAME": JSON.stringify(
+        process.env.ALGOLIA_INDEX_NAME ?? "",
+      ),
+      "import.meta.env.VITE_ALGOLIA_SEARCH_KEY": JSON.stringify(
+        process.env.ALGOLIA_SEARCH_KEY ?? "",
+      ),
     },
     plugins: [sassDts()],
   },

docs/src/content/docs/openapi-fetch/api.md

@@ -34,6 +34,7 @@ client.get("/my-url", options);
 | `querySerializer` |                          QuerySerializer                          | (optional) Provide a [querySerializer](#queryserializer)                                                                                                                                                                                                                               |
 | `bodySerializer`  |                          BodySerializer                           | (optional) Provide a [bodySerializer](#bodyserializer)                                                                                                                                                                                                                                 |
 | `parseAs`         | `"json"` \| `"text"` \| `"arrayBuffer"` \| `"blob"` \| `"stream"` | (optional) Parse the response using <a href="https://developer.mozilla.org/en-US/docs/Web/API/Response#instance_methods" target="_blank" rel="noopener noreferrer">a built-in instance method</a> (default: `"json"`). `"stream"` skips parsing altogether and returns the raw stream. |
+| `fetch`           |                              `fetch`                              | Fetch instance used for requests (default: fetch from `createClient`)                                                                                                                                                                                                                  |
 | (Fetch options)   |                                                                   | Any valid fetch option (`headers`, `mode`, `cache`, `signal`, …) (<a href="https://developer.mozilla.org/en-US/docs/Web/API/fetch#options" target="_blank" rel="noopener noreferrer">docs</a>)                                                                                         |
 
 ### querySerializer

docs/src/content/docs/openapi-fetch/examples.md

@@ -90,7 +90,7 @@ openapi-fetch is simple vanilla JS that can be used in any project. But sometime
 
 ### Svelte / SvelteKit
 
-<a href="https://kit.svelte.dev" target="_blank" rel="noopener noreferrer">SvelteKit</a>’s automatic type inference can easily pick up openapi-fetch’s types in both clientside fetching and <a href="https://kit.svelte.dev/docs/load#page-data" target="_blank" rel="noopener noreferrer">Page Data</a> fetching. And it doesn’t need any additional libraries to work.
+<a href="https://kit.svelte.dev" target="_blank" rel="noopener noreferrer">SvelteKit</a>’s automatic type inference can easily pick up openapi-fetch’s types in both clientside fetching and <a href="https://kit.svelte.dev/docs/load#page-data" target="_blank" rel="noopener noreferrer">Page Data</a> fetching. And it doesn’t need any additional libraries to work. SvelteKit also advises to use their <a href="https://kit.svelte.dev/docs/load#making-fetch-requests" target="_blank" rel="noopener noreferrer">custom fetch</a> in load functions - this can be achieved with <a href='/openapi-fetch/api#fetch-options'>fetch options</a>.
 
 _Note: if you’re using Svelte without SvelteKit, the root example in `src/routes/+page.svelte` doesn’t use any SvelteKit features and is generally-applicable to any setup._
 

packages/openapi-fetch/examples/sveltekit/src/hooks.server.ts

@@ -0,0 +1,10 @@
+import type { Handle } from "@sveltejs/kit";
+
+export const handle: Handle = async ({ event, resolve }) => {
+  return resolve(event, {
+    filterSerializedResponseHeaders(name) {
+      // SvelteKit doesn't serialize any headers on server-side fetches by default but openapi-fetch uses this header for empty responses.
+      return name === "content-length";
+    },
+  });
+};

packages/openapi-fetch/examples/sveltekit/src/lib/api/index.ts

@@ -1,12 +1,5 @@
 import createClient from "openapi-fetch";
 import type { paths } from "./v1";
-import type { PageServerLoadEvent } from "../../routes/page-data/$types";
 
 const client = createClient<paths>({ baseUrl: "https://catfact.ninja/" });
 export default client;
-
-export const createServerClient = (fetcher: PageServerLoadEvent["fetch"]) =>
-  createClient<paths>({
-    baseUrl: "https://catfact.ninja/",
-    fetch: fetcher,
-  });

packages/openapi-fetch/examples/sveltekit/src/routes/page-data/+page.server.ts → packages/openapi-fetch/examples/sveltekit/src/routes/page-data/+page.ts

@@ -1,14 +1,12 @@
-import { createServerClient } from "$lib/api/index.js";
+import client from "$lib/api/index.js";
 
 // Note: this uses Svelte’s custom fetcher as an example, but Node’s
 // native fetch works, too. See Svelte’s docs to learn the difference:
 // @see https://kit.svelte.dev/docs/load#making-fetch-requests
 export async function load({ fetch }) {
-  const client = createServerClient(fetch);
   const fact = await client.GET("/fact", {
-    params: {
-      query: { max_length: 500 },
-    },
+    params: { query: { max_length: 500 } },
+    fetch,
   });
 
   return {

packages/openapi-fetch/src/index.test.ts

@@ -396,18 +396,26 @@ describe("client", () => {
     });
 
     it("accepts a custom fetch function", async () => {
-      const data = { works: true };
-      const customFetch = {
-        clone: () => ({ ...customFetch }),
-        headers: new Headers(),
-        json: async () => data,
-        status: 200,
-        ok: true,
-      };
-      const client = createClient<paths>({
-        fetch: async () => Promise.resolve(customFetch as Response),
-      });
-      expect((await client.GET("/self")).data).toBe(data);
+      function createCustomFetch(data: any) {
+        const response = {
+          clone: () => ({ ...response }),
+          headers: new Headers(),
+          json: async () => data,
+          status: 200,
+          ok: true,
+        } as Response;
+        return async () => Promise.resolve(response);
+      }
+
+      const baseData = { works: true };
+      const customBaseFetch = createCustomFetch(baseData);
+      const client = createClient<paths>({ fetch: customBaseFetch });
+      expect((await client.GET("/self")).data).toBe(baseData);
+
+      const data = { result: "it's working" };
+      const customFetch = createCustomFetch(data);
+      const customResponse = await client.GET("/self", { fetch: customFetch });
+      expect(customResponse.data).toBe(data);
     });
   });
 

packages/openapi-fetch/src/index.ts

@@ -70,7 +70,8 @@ export type RequestBodyOption<T> = OperationRequestBodyContent<T> extends never
   ? { body?: OperationRequestBodyContent<T> }
   : { body: OperationRequestBodyContent<T> };
 
-export type FetchOptions<T> = RequestOptions<T> & Omit<RequestInit, "body">;
+export type FetchOptions<T> = RequestOptions<T> &
+  Omit<RequestInit, "body"> & { fetch?: ClientOptions["fetch"] };
 
 export type FetchResponse<T> =
   | {
@@ -95,7 +96,7 @@ export default function createClient<Paths extends {}>(
   clientOptions: ClientOptions = {},
 ) {
   const {
-    fetch = globalThis.fetch,
+    fetch: baseFetch = globalThis.fetch,
     querySerializer: globalQuerySerializer,
     bodySerializer: globalBodySerializer,
     ...options
@@ -110,6 +111,7 @@ export default function createClient<Paths extends {}>(
     fetchOptions: FetchOptions<M extends keyof Paths[P] ? Paths[P][M] : never>,
   ): Promise<FetchResponse<M extends keyof Paths[P] ? Paths[P][M] : unknown>> {
     const {
+      fetch = baseFetch,
       headers,
       body: requestBody,
       params = {},