docs: link to example fetcher + inline example

Author: astahmer

README.md

@@ -10,7 +10,7 @@ See [the online playground](https://typed-openapi-astahmer.vercel.app/)
 
 ## Features
 
-- Headless API client, bring your own fetcher ! (fetch, axios, ky, etc...)
+- Headless API client, [bring your own fetcher](packages/typed-openapi/API_CLIENT_EXAMPLES.md#basic-api-client-api-client-examplets) (fetch, axios, ky, etc...) !
 - Generates a fully typesafe API client with just types by default (instant suggestions)
 - **Type-safe error handling** with discriminated unions and configurable success status codes
 - **TanStack Query integration** with `withResponse` and `selectFn` options for advanced error handling

packages/typed-openapi/API_CLIENT_EXAMPLES.md

@@ -11,6 +11,94 @@ A simple, dependency-free client that handles:
 - Custom headers
 - Basic error handling
 
+```typescript
+/**
+ * Generic API Client for typed-openapi generated code
+ *
+ * This is a simple, production-ready wrapper that you can copy and customize.
+ * It handles:
+ * - Path parameter replacement
+ * - Query parameter serialization
+ * - JSON request/response handling
+ * - Basic error handling
+ *
+ * Usage:
+ * 1. Replace './generated/api' with your actual generated file path
+ * 2. Set your API_BASE_URL
+ * 3. Customize error handling and headers as needed
+ */
+
+import { type Fetcher, createApiClient  } from "../tmp/generated-client.ts";
+
+// Basic configuration
+const API_BASE_URL = process.env["API_BASE_URL"] || "https://api.example.com";
+
+/**
+ * Simple fetcher implementation without external dependencies
+ */
+const fetcher: Fetcher = async (method, apiUrl, params) => {
+  const headers = new Headers();
+
+  // Replace path parameters (supports both {param} and :param formats)
+  const actualUrl = replacePathParams(apiUrl, (params?.path ?? {}) as Record<string, string>);
+  const url = new URL(actualUrl);
+
+  // Handle query parameters
+  if (params?.query) {
+    const searchParams = new URLSearchParams();
+    Object.entries(params.query).forEach(([key, value]) => {
+      if (value != null) {
+        // Skip null/undefined values
+        if (Array.isArray(value)) {
+          value.forEach((val) => val != null && searchParams.append(key, String(val)));
+        } else {
+          searchParams.append(key, String(value));
+        }
+      }
+    });
+    url.search = searchParams.toString();
+  }
+
+  // Handle request body for mutation methods
+  const body = ["post", "put", "patch", "delete"].includes(method.toLowerCase())
+    ? JSON.stringify(params?.body)
+    : undefined;
+
+  if (body) {
+    headers.set("Content-Type", "application/json");
+  }
+
+  // Add custom headers
+  if (params?.header) {
+    Object.entries(params.header).forEach(([key, value]) => {
+      if (value != null) {
+        headers.set(key, String(value));
+      }
+    });
+  }
+
+  const response = await fetch(url, {
+    method: method.toUpperCase(),
+    ...(body && { body }),
+    headers,
+  });
+
+  return response;
+};
+
+/**
+ * Replace path parameters in URL
+ * Supports both OpenAPI format {param} and Express format :param
+ */
+function replacePathParams(url: string, params: Record<string, string>): string {
+  return url
+    .replace(/{(\w+)}/g, (_, key: string) => params[key] || `{${key}}`)
+    .replace(/:([a-zA-Z0-9_]+)/g, (_, key: string) => params[key] || `:${key}`);
+}
+
+export const api = createApiClient(fetcher, API_BASE_URL);
+```
+
 ### Setup
 
 1. Copy the file to your project