feat(types): allow passing interfaces as Bindings / Variables (#3136)

* feat(types): allow passing `interface`s as Bindings / Variables

* test(context): add test for c.var

* fix lint warning

* test(types): add test for Bindings types

src/context.test.ts

@@ -88,6 +88,13 @@ describe('Context', () => {
     expect(c.get('foo2')).toBe(undefined)
   })
 
+  it('c.var', async () => {
+    expect(c.var.foo).toBe(undefined)
+    c.set('foo', 'bar')
+    expect(c.var.foo).toBe('bar')
+    expect(c.var.foo2).toBe(undefined)
+  })
+
   it('c.notFound()', async () => {
     const res = c.notFound()
     expect(res).instanceOf(Response)

src/context.ts

@@ -265,7 +265,7 @@ export class Context<
    * ```
    */
   env: E['Bindings'] = {}
-  #var: E['Variables'] | undefined
+  #var: Map<unknown, unknown> | undefined
   finalized: boolean = false
   /**
    * `.error` can get the error object from the middleware if the Handler throws an error.
@@ -521,9 +521,9 @@ export class Context<
    * ```
 ```
    */
-  set: Set<E> = (key: string, value: unknown) => {
-    this.#var ??= {}
-    this.#var[key as string] = value
+  set: Set<E> = (key: unknown, value: unknown) => {
+    this.#var ??= new Map()
+    this.#var.set(key, value)
   }
 
   /**
@@ -539,8 +539,8 @@ export class Context<
    * })
    * ```
    */
-  get: Get<E> = (key: string) => {
-    return this.#var ? this.#var[key] : undefined
+  get: Get<E> = (key: unknown) => {
+    return this.#var ? this.#var.get(key) : undefined
   }
 
   /**
@@ -558,7 +558,11 @@ export class Context<
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     ContextVariableMap & (IsAny<E['Variables']> extends true ? Record<string, any> : E['Variables'])
   > {
-    return { ...this.#var } as never
+    if (!this.#var) {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      return {} as any
+    }
+    return Object.fromEntries(this.#var)
   }
 
   newResponse: NewResponse = (

src/hono.test.ts

@@ -3585,3 +3585,36 @@ describe('Compatible with extended Hono classes, such Zod OpenAPI Hono.', () =>
     expect(res.status).toBe(200)
   })
 })
+
+describe('Generics for Bindings and Variables', () => {
+  interface CloudflareBindings {
+    MY_VARIABLE: string
+  }
+
+  it('Should not throw type errors', () => {
+    // @ts-expect-error Bindings should extend object
+    new Hono<{
+      Bindings: number
+    }>()
+
+    const appWithInterface = new Hono<{
+      Bindings: CloudflareBindings
+    }>()
+
+    appWithInterface.get('/', (c) => {
+      expectTypeOf(c.env.MY_VARIABLE).toMatchTypeOf<string>()
+      return c.text('/')
+    })
+
+    const appWithType = new Hono<{
+      Bindings: {
+        foo: string
+      }
+    }>()
+
+    appWithType.get('/', (c) => {
+      expectTypeOf(c.env.foo).toMatchTypeOf<string>()
+      return c.text('Hello Hono!')
+    })
+  })
+})

src/preset/quick.test.ts

@@ -7,3 +7,36 @@ describe('hono/quick preset', () => {
     expect(getRouterName(app)).toBe('SmartRouter + LinearRouter')
   })
 })
+
+describe('Generics for Bindings and Variables', () => {
+  interface CloudflareBindings {
+    MY_VARIABLE: string
+  }
+
+  it('Should not throw type errors', () => {
+    // @ts-expect-error Bindings should extend object
+    new Hono<{
+      Bindings: number
+    }>()
+
+    const appWithInterface = new Hono<{
+      Bindings: CloudflareBindings
+    }>()
+
+    appWithInterface.get('/', (c) => {
+      expectTypeOf(c.env.MY_VARIABLE).toMatchTypeOf<string>()
+      return c.text('/')
+    })
+
+    const appWithType = new Hono<{
+      Bindings: {
+        foo: string
+      }
+    }>()
+
+    appWithType.get('/', (c) => {
+      expectTypeOf(c.env.foo).toMatchTypeOf<string>()
+      return c.text('Hello Hono!')
+    })
+  })
+})

src/preset/tiny.test.ts

@@ -7,3 +7,36 @@ describe('hono/tiny preset', () => {
     expect(getRouterName(app)).toBe('PatternRouter')
   })
 })
+
+describe('Generics for Bindings and Variables', () => {
+  interface CloudflareBindings {
+    MY_VARIABLE: string
+  }
+
+  it('Should not throw type errors', () => {
+    // @ts-expect-error Bindings should extend object
+    new Hono<{
+      Bindings: number
+    }>()
+
+    const appWithInterface = new Hono<{
+      Bindings: CloudflareBindings
+    }>()
+
+    appWithInterface.get('/', (c) => {
+      expectTypeOf(c.env.MY_VARIABLE).toMatchTypeOf<string>()
+      return c.text('/')
+    })
+
+    const appWithType = new Hono<{
+      Bindings: {
+        foo: string
+      }
+    }>()
+
+    appWithType.get('/', (c) => {
+      expectTypeOf(c.env.foo).toMatchTypeOf<string>()
+      return c.text('Hello Hono!')
+    })
+  })
+})

src/types.ts

@@ -24,8 +24,8 @@ import type {
 //////                            //////
 ////////////////////////////////////////
 
-export type Bindings = Record<string, unknown>
-export type Variables = Record<string, unknown>
+export type Bindings = object
+export type Variables = object
 
 export type BlankEnv = {}
 export type Env = {