feat: c.req.param() schema validation

handler.ts

@@ -68,15 +68,16 @@ export function handler<T>() {
     pathname: Pathname,
     // deno-lint-ignore no-unused-vars
     ...handler: (
-      | {
+      | ({
         body?: ValidatedBody
         cookies?: ValidatedCookies
         headers?: ValidatedHeaders
         query?: ValidatedQuery
         /** @deprecated please pass this option to the `c.req.body()` method! */
         transform?: boolean // TODO remove at v2.0
         cors?: string
-      }
+        params?: Partial<Record<keyof ExtractParams<Pathname>, ZodType>>
+      })
       | Handler<
         Pathname,
         ValidatedBody,
@@ -124,6 +125,7 @@ export function bodylessHandler<T>() {
         headers?: ValidatedHeaders
         query?: ValidatedQuery
         cors?: string
+        params?: Partial<Record<keyof ExtractParams<Pathname>, ZodType>>
       }
       | BodylessHandler<
         Pathname,
@@ -147,6 +149,7 @@ export type HandlerOrSchema =
     /** @deprecated please pass this option to the `c.req.body()` method! */
     transform?: boolean // TODO remove at v2.0
     cors?: string
+    params?: Record<string, ZodType>
   }
   | Handler<unknown>
   | BodylessHandler<unknown>

request_context.ts

@@ -41,6 +41,7 @@ export class RequestContext<
       cookies?: ObjectType | undefined
       headers?: ObjectType | undefined
       query?: ObjectType | undefined
+      params?: Record<string, ZodType>
       [key: string]: unknown
     } | null,
     e: Context['exception'],
@@ -70,8 +71,17 @@ export class RequestContext<
    * A method to retrieve the corresponding value of a parameter.
    */
   param<T extends keyof Params>(name: T): Params[T] {
-    // @ts-ignore:
-    return this.#p[name]
+    if (this.#s?.params && this.#s.params[name as string]) {
+      const result = this.#s.params[name as string].safeParse(this.#p[name])
+
+      if (!result.success) {
+        throw this.#e('Bad Request')
+      }
+
+      return result.data as Params[T]
+    } else {
+      return this.#p[name as string] as Params[T]
+    }
   }
 
   /**

test/validation.test.ts

@@ -215,4 +215,38 @@ Deno.test('Validation', async (t) => {
       { second: false, third: 69 },
     )
   })
+
+  await t.step('params', async () => {
+    const app = new cheetah()
+
+    app.get(
+      '/animals/:name',
+      {
+        params: {
+          name: z.union([z.literal('cat'), z.literal('dog')]),
+        },
+      },
+      (c) => {
+        return c.req.param('name')
+      },
+    )
+
+    const res1 = await app.fetch(
+      new Request('http://localhost/animals/cat'),
+    )
+
+    assertEquals(res1.status, 200)
+
+    const res2 = await app.fetch(
+      new Request('http://localhost/animals/dog'),
+    )
+
+    assertEquals(res2.status, 200)
+
+    const res3 = await app.fetch(
+      new Request('http://localhost/animals/rabbit'),
+    )
+
+    assertEquals(res3.status, 400)
+  })
 })