34 lines
2.3 KiB
TypeScript
Executable File
34 lines
2.3 KiB
TypeScript
Executable File
import { type ReadonlyHeaders } from '../web/spec-extension/adapters/headers';
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/**
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* In this version of Next.js `headers()` returns a Promise however you can still reference the properties of the underlying Headers instance
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* synchronously to facilitate migration. The `UnsafeUnwrappedHeaders` type is added to your code by a codemod that attempts to automatically
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* updates callsites to reflect the new Promise return type. There are some cases where `headers()` cannot be automatically converted, namely
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* when it is used inside a synchronous function and we can't be sure the function can be made async automatically. In these cases we add an
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* explicit type case to `UnsafeUnwrappedHeaders` to enable typescript to allow for the synchronous usage only where it is actually necessary.
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*
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* You should should update these callsites to either be async functions where the `headers()` value can be awaited or you should call `headers()`
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* from outside and await the return value before passing it into this function.
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*
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* You can find instances that require manual migration by searching for `UnsafeUnwrappedHeaders` in your codebase or by search for a comment that
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* starts with `@next-codemod-error`.
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*
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* In a future version of Next.js `headers()` will only return a Promise and you will not be able to access the underlying Headers instance
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* without awaiting the return value first. When this change happens the type `UnsafeUnwrappedHeaders` will be updated to reflect that is it no longer
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* usable.
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*
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* This type is marked deprecated to help identify it as target for refactoring away.
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*
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* @deprecated
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*/
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export type UnsafeUnwrappedHeaders = ReadonlyHeaders;
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/**
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* This function allows you to read the HTTP incoming request headers in
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* [Server Components](https://nextjs.org/docs/app/building-your-application/rendering/server-components),
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* [Server Actions](https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations),
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* [Route Handlers](https://nextjs.org/docs/app/building-your-application/routing/route-handlers) and
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* [Middleware](https://nextjs.org/docs/app/building-your-application/routing/middleware).
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*
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* Read more: [Next.js Docs: `headers`](https://nextjs.org/docs/app/api-reference/functions/headers)
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*/
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export declare function headers(): Promise<ReadonlyHeaders>;
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