Скачать или смотреть Accessing getServerSideProps Data in Your Custom Document for Next.js

Discover how to seamlessly pass data from `getServerSideProps` to your `_document.js` in Next.js, enhancing performance and user experience.
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Accessing getServerSideProps Data in Your Custom Document for Next.js

Next.js is a powerful framework that supports server-side rendering (SSR) using getServerSideProps. However, developers often encounter challenges when it comes to accessing the data fetched in getServerSideProps within the _document.js file of a Next.js application. This post will guide you through the steps needed to achieve this, helping to eliminate issues like flashing during page loads.

Understanding the Problem

When using getServerSideProps, data is fetched on the server side, and that data is then passed to your page component as props. While _document.js is responsible for rendering the overall HTML structure of your application, it does not have direct access to the same props as your page components. However, you might want to utilize certain data (like a theme or class name) in _document.js to enhance styles and prevent flashing effects during loading.

A Hacky Solution to the Problem

While there isn't an official way to directly pass the data from getServerSideProps into _document.js, there is a workaround that can achieve the desired result.

Step-by-Step Approach

Fetching Data in getServerSideProps: Start by implementing your getServerSideProps function, where you will fetch the required data. For example, you might fetch event data based on an ID.

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Render Data in Page Component: In your page component, you can create an empty div that will store the fetched data within your HTML structure. This data will later be accessed in _document.js.

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

Modify _document.js: Open your _document.js, which will allow you to manipulate the server-rendered HTML and check if you are on the appropriate page:

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

Explanation of the Code

Server Check: The code first checks if the request is a server-side request and whether it is pointing to the correct route (/j/[shortId]). This ensures any modifications made to the document only apply when necessary.

HTML Parsing: The initialProps.html contains the HTML that was rendered with your data. By searching for your custom data attribute, you can extract the desired value related to your event theme.

Returning Props: The extracted value is then added to the props that will be passed to the _document.js, allowing you to set classes or data attributes based on SSR data.

Conclusion

While this method provides a rather hacky approach to accessing getServerSideProps data in _document.js, it serves well to enhance the user experience by minimizing flashing and improving performance. However, due caution is advised when implementing this technique as it relies on parsing HTML and can lead to maintenance challenges in the future.

For developers looking for a more official way to handle data across different contexts in Next.js, monitoring updates to the framework could yield new, improved methodologies.

Remember, always test thoroughly in your specific environment and ensure your solution maintains performance across all use cases!