feat: add support for header validation and aggregation in fetch schema (#65)

Author: karol-broda

dev/index.ts

@@ -1,23 +1,37 @@
-import { betterFetch, createFetch, createSchema } from "@better-fetch/fetch";
+import { createFetch, createSchema } from "@better-fetch/fetch";
 import { z } from "zod";
-
+ 
 const $fetch = createFetch({
-	schema: createSchema({
-		"@patch/user": {
-			input: z.object({
-				id: z.string(),
+    baseURL: "https://jsonplaceholder.typicode.com",
+    schema: createSchema({
+        "/path": {
+            input: z.object({
+                userId: z.string(),
+                id: z.number(),
+                title: z.string(),
+                completed: z.boolean(),
+            }),
+			headers: z.object({
+				"x-custom-header": z.string(),
 			}),
-		},
-	}),
-	baseURL: "http://localhost:3000",
-	onRequest(context) {
-		console.log("onRequest", JSON.parse(context.body));
+        },
+    }), 
+	auth: {
+		type: "Bearer",
+		token:"test-token",
+	}
+})
+ 
+const { data, error } = await $fetch("/path", {
+    body: {
+        userId: "1",
+        id: 1,
+        title: "title",
+        completed: true,
+    },
+	headers: {
+		"x-custom-header": "custom-value",
 	},
-});
+})
 
-const f = $fetch("https://jsonplaceholder.typicode.com/todos/:id", {
-	method: "GET",
-	params: {
-		id: "1",
-	},
-});
+console.log(data, error);

doc/content/docs/authorization.mdx

@@ -6,6 +6,10 @@ description: Authorization
 Authorization is a way that allows you to add authentication headers to the request.
 Currently, supports `Bearer` and `Basic` authorization.
 
+<Callout type="info">
+For more advanced header handling and validation, see the [Headers](/docs/headers) documentation.
+</Callout>
+
 ### Bearer
 
 The bearer authorization is used to add a bearer token to the request. The token is added to the `Authorization` header. 

doc/content/docs/fetch-schema.mdx

@@ -47,9 +47,13 @@ const $fetch = createFetch({
 ## Fetch Schema
 
 The Fetch Schema is a map of path/url and schema. The path is the url path and the schema is an object with 
-`input`, `output`, `query` and `params` keys.
+`input`, `output`, `query`, `params`, and `headers` keys.
 
-The `input` key is the schema of the request data. The `output` key is the schema of the response data. The `query` key is the schema of the query params. The `params` key is dynamic path parameters.
+The `input` key is the schema of the request data. The `output` key is the schema of the response data. The `query` key is the schema of the query params. The `params` key is dynamic path parameters. The `headers` key is for header validation.
+
+<Callout type="info">
+For detailed information about header validation and types, see the [Headers](/docs/headers) documentation.
+</Callout>
 
 ### Input
 
@@ -143,6 +147,38 @@ const { data, error } = await $fetch("/path", {
 // @annotate: Hover over the data object to see the type
 ```
 
+### Headers
+
+The headers schema is the schema of the request headers. You can define header validation using Zod or any StandardSchema library.
+
+```ts title="fetch.ts"
+import { createFetch, createSchema } from "@better-fetch/fetch";
+import { z } from "zod";
+
+const $fetch = createFetch({
+    baseURL: "http://localhost:3000",
+    schema: createSchema({
+        "/api/users": {
+            headers: z.object({
+                "x-api-key": z.string(),
+                "x-user-id": z.string().uuid(),
+            }),
+        },
+    }),
+})
+
+const { data } = await $fetch("/api/users", {
+    headers: {
+        "x-api-key": "my-key",
+        "x-user-id": "123e4567-e89b-12d3-a456-426614174000",
+    },
+})
+```
+
+<Callout type="info">
+Header keys should be defined in lowercase for case-insensitive matching. See [Headers](/docs/headers) for more details.
+</Callout>
+
 ### Dynamic Path Parameters
 
 The params schema is the schema of the path params. You can either use the `params` key to define the paramters or prepend `:` to the path to make the parameters dynamic. 

doc/content/docs/getting-started.mdx

@@ -100,14 +100,16 @@ Learn more about handling errors [Handling Errors](/docs/handling-errors) sectio
 
 ### Fetch Schema
 
-Fetch schema enables you to pre-define the URL path and the shape of request and response data. This makes it easy to document your API. 
+Fetch schema enables you to pre-define the URL path and the shape of request and response data, including headers, query parameters, and path parameters. This makes it easy to document your API. 
 
 <Callout type="info">
    Plugins can also define fetch schemas. See [Plugins](/docs/plugins) section for more details.
 </Callout>
 
 The output of the schema will be validated using your schema and if the validation fails, it'll throw an error.
 
+You can validate headers, request body, query params, and more. See [Fetch Schema](/docs/fetch-schema) and [Headers](/docs/headers) for more details.
+
 ```ts twoslash title="fetch.ts" 
 import { createSchema, createFetch } from "@better-fetch/fetch";