Did you know that Next.js Server Actions can return React Components JSX instead of raw JSON data?
While it's not explicitly mentioned in the docs, I was pleasantly surprised that it works.
Example
I have a page that renders users list with server action:
export default function Page() {
async function loadUsersAction() {
"use server";
return [
{ name: "John", age: 30 },
{ name: "Jane", age: 25 },
{ name: "Doe", age: 40 },
];
}
return <UsersList loadUsersAction={loadUsersAction} />;
}
UsersList component loads users by button click:
'use client';
import { useState } from 'react';
export default function UsersList({ loadUsersAction }) {
const [users, setUsers] = useState();
const onClick = async () => {
const data = await loadUsersAction();
setUsers(data);
};
return (
<>
<button onClick={onClick}>Load users</button>
<ul>
{users?.map((user) => (
<li key={user.name}>
{user.name} - {user.age}
</li>
))}
</ul>
</>
);
}
Demo:
Now I change server action to return JSX with rendered users:
async function loadUsersAction() {
"use server";
const users = [
{ name: "John", age: 30 },
{ name: "Jane", age: 25 },
{ name: "Doe", age: 40 },
];
return (
<ul>
{users?.map((user) => (
<li key={user.name}>
{user.name} - {user.age}
</li>
))}
</ul>
);
}
And in UsersList component just render server action response:
export default function UsersList({ loadUsersAction }) {
const [users, setUsers] = useState();
const onClick = async () => {
const data = await loadUsersAction();
setUsers(data);
};
return (
<>
<button onClick={onClick}>Load users</button>
{users}
</>
);
}
In browser everything works in the same way!
Note on errors handling
What if server action throws an error? When it returns a JSON data, we can catch that error inside action and return it in own format like:
{ error: "my error" }
When returning JSX, we can let error throw and catch it on the client with the nearest error boundary. As server action is called not inside a <form> element, it should be wrapped into Transition for proper errors handling. For Next.js it means that the nearest error.tsx file will be displayed in case of error.
The final code of UsersList component:
'use client';
import { useState, useTransition } from 'react';
export default function UsersList({ loadUsersAction }) {
const [isPending, startTransition] = useTransition();
const [users, setUsers] = useState();
const onClick = () => {
startTransition(async () => {
const data = await loadUsersAction();
setUsers(data);
});
};
return (
<>
<button onClick={onClick}>Load users</button>
{isPending ? <div>Loading users...</div> : users}
</>
);
}
Additionally, I utilize isPending flag to show message while loading users.
Demo:
You can check out a fully working example on GitHub.
Thanks for reading and happy coding! ❤️
Top comments (4)
while it's very cool, where is the separation of concerns here?
what if in some years your company (or you) decides to refactor your code, ditch Nextjs, and go back to APIs?
my advice is treat actions like if they were API endpoints, also when it comes to security
I agree, it's more vendor lock, compared to traditional API calls. That's the payment for conveniency, a trade-off as always.
Personally, I think server actions will become more used in other frameworks, not only in Next.js. As they are core React feature and a part of Server Components, that will be stable in React 19.
I've checked Astro, it has similar actions approach.
Good easy to understand example!
I don't know much about SA. Do they accept generic parameters beyond FormData (as I saw in a video)? They can also return any type of data, as in those examples JSON (or a JS object), JSX and more? Thank you for your great article.