Скачать или смотреть Handling the Cannot read properties of null (reading 'useContext') Error in Next.js Router

Learn how to solve the common Next.js error regarding the use of `useContext` with routing and API pages effectively.
---
This video is based on the question https://stackoverflow.com/q/75595118/ asked by the user 'João Silva' ( https://stackoverflow.com/u/13526575/ ) and on the answer https://stackoverflow.com/a/75609500/ provided by the user 'Saar' ( https://stackoverflow.com/u/18204979/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Using Next.JS Router Error: Cannot read properties of null (reading 'useContext')

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding the Cannot read properties of null (reading 'useContext') Error in Next.js

If you're just starting your journey with Next.js and React, encountering errors can be frustrating, especially when you're trying to implement functionalities like routing. One common issue beginners face is the Cannot read properties of null (reading 'useContext') error when using the router in API pages. In this guide, we’ll break down the problem and provide a clear solution to help you redirect users effectively to dynamic project details.

The Issue at Hand

The problem arises when trying to use the useRouter hook in an API route in Next.js. Here’s the scenario:

Redirecting to Project Details: You have a function meant to redirect users to a project detail page.

[[See Video to Reveal this Text or Code Snippet]]

Using useRouter: In your API page, you attempt to retrieve the project identifier with:

[[See Video to Reveal this Text or Code Snippet]]

Error Encountered: You face the error stating Cannot read properties of null (reading 'useContext'). This is primarily because you cannot use React hooks like useRouter in API pages.

Understanding API Pages in Next.js

Before diving into the solution, it’s important to understand what API pages are meant for:

API Pages: These are used for server-side logic and usually return data in JSON format, not HTML.

Client-Side Pages: These are intended for rendering UI components and can utilize hooks like useRouter.

Given that your intention is to redirect to a project detail page that renders HTML, you should opt for a page route instead of an API route.

Solution: Use Dynamic Pages Instead of API Pages

Step 1: Change Your Page Route

Instead of using /api/[key].js, consider creating a dynamic route:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update the ProjectDetails Component

Modify the ProjectDetails function to extract the key from the route parameters. Here’s how you would do it:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Update the Redirect Function

With the new page in place, your redirect function should change to:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By switching from an API route to a dynamic page for your project details, you not only resolve the useContext error but also leverage Next.js routing capabilities effectively. This helps in improving the overall user experience and keeps your code cleaner.

With practice, you'll become adept at navigating through Next.js architecture and its routing mechanisms. Keep experimenting, and happy coding!