In a Next 14 app with app router, how could I set up a context + context provider, fetch the products and use the context to store these? I have a route app/netshop with a page.tsx and a layout.tsx. Should I fetch and set the state context from the layout file, and in that case how would you solve it?
#product state context in NextJs 14.1 with app router
autumn pond
limber pierBOT
Hi @autumn pond. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:
In Next.js 14 with the App Router, you can set up a context and context provider to fetch and store products. Here's how you can do it:
- Create a Context and Context Provider: You can create a context and a context provider in a separate file. This provider can be used to fetch the products and store them in the state. Here's an example from a Github issue (https://github.com/vercel/next.js/issues/52448) where a context and a context provider are created:
export const AppContext = createContext({} as {
currentUser?: ICurrentUser,
login: (user: ICurrentUser) => void,
});
const userStorageKey = "key";
export default function AppContextProvider({
children,
}: {
children: React.ReactNode
}) {
const [currentUser, setCurrentUser] = useState(JSON.parse(localStorage.getItem(userStorageKey) ?? "{}") as ICurrentUser);
const login = useCallback((user: ICurrentUser) => {
localStorage.setItem(userStorageKey, JSON.stringify(user));
setCurrentUser(user);
}, []);
const contextValue = useMemo(() => ({
currentUser,
login,
}), [currentUser, login]);
return (
<AppContext.Provider value={contextValue}>
{children}
</AppContext.Provider>
);
}
In your case, you would replace currentUser with products, and login with a function to fetch and set the products.
- Use the Context Provider in the Layout: You can use the context provider in your
layout.tsxfile. This is where you would fetch the products and set them in the state. Here's an example from the Next.js documentation (https://nextjs.org/docs/app/building-your-application/rendering/composition-patterns#using-context-providers) where a context provider is used in a layout:
import ThemeProvider from './theme-provider'
export default function RootLayout({
children,
}: {
children: React.ReactNode
}) {
return (
<html>
<body>
<ThemeProvider>{children}</ThemeProvider>
</body>
</html>
)
}
In your case, you would replace ThemeProvider with your AppContextProvider.
- Use the Context in the Page: Finally, you can use the context in your
page.tsxfile to access the products. You can do this using theuseContexthook from React.
Remember, if you need to use state or lifecycle effects (like useState), you should use the use client directive at the start of your component to tell React it will be a Client Component, as mentioned in this Github issue (https://github.com/vercel/next.js/issues/49839).
Please note that this is a general guide and you might need to adjust the code to fit your specific use case.
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
autumn pond
@limber pier I currently fetch the products in app/netshop/page.tsx and render the product cards there. I just need to access the list of products in the cart which is under the Navbar client-component, and then at a check-out page. What would be the most efficient code structure: to fetch the products for the netshop in app/netshop/page.tsx and render the product cards, then fetch again in the layout.tsx and set the state, or could I do it in another more efficient way`
limber pierBOT
Let me check the knowledge base for you. One moment! :books:
In terms of efficiency and performance, it's generally a good practice to fetch data once and then distribute it to the components that need it. This can be achieved by using a context provider at a higher level in your component tree, and then consuming the context in the components that need the data.
Here's a suggested approach:
-
Fetch the Products in the Layout: You can fetch the products in your
layout.tsxfile and store them in the state using a context provider. This way, the products are fetched once when the layout is rendered, and they are available to all the child components. -
Access the Products in the Page and Navbar: You can then use the
useContexthook in yourapp/netshop/page.tsxfile and the Navbar component to access the products from the context. This way, you don't need to fetch the products again in these components. -
Access the Products in the Checkout Page: Similarly, you can use the
useContexthook in your checkout page to access the products from the context.
This approach ensures that the products are fetched only once and are available to all the components that need them. It also keeps your components clean and focused on rendering, as they don't need to handle data fetching.
Remember, if you need to use state or lifecycle effects (like useState), you should use the use client directive at the start of your component to tell React it will be a Client Component, as mentioned in this Github issue (https://github.com/vercel/next.js/issues/49839).
Please note that this is a general guide and you might need to adjust the code to fit your specific use case.
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
autumn pond
@limber pier ok, but then do I need to make the layout.tsx a "client component" ?
limber pierBOT
Let me check the knowledge base for you. One moment! :books:
Yes, if you're planning to use state or lifecycle effects (like useState or useEffect) in your layout.tsx file, you should make it a Client Component. You can do this by adding the use client directive at the start of your component.
Here's an example from the Next.js documentation (https://nextjs.org/docs/app/building-your-application/rendering/composition-patterns#using-context-providers):
'use client'
import { createContext } from 'react'
export const ThemeContext = createContext({})
export default function ThemeProvider({
children,
}: {
children: React.ReactNode
}) {
return <ThemeContext.Provider value="dark">{children}</ThemeContext.Provider>
}
In this example, ThemeProvider is a Client Component because it uses the use client directive. In your case, you would replace ThemeProvider with your RootLayout component.