🔥 Fixing Next.js Hydration Error with Shadcn Dialog Component

Introduction

Hydration errors in Next.js often occur when the server-rendered HTML does not match the client-rendered content. This can be particularly problematic when using Shadcn Dialog components. In this article, we will address common causes of these errors and provide solutions to ensure a seamless integration of Shadcn Dialog with Next.js.

The Problem

When using Shadcn Dialog in a Next.js application, you might encounter the following error:

Hydration failed because the initial UI does not match what was rendered on the server.

This issue arises because:

1. Server-Side Rendering (SSR): The dialog's initial rendering on the server may differ from the client's dynamic behavior.
2. Radix UI Primitives: Components like Shadcn Dialog rely on client-side interactivity that conflicts with SSR.
3. State Mismatches: Dialogs often rely on client-only state, which may not be initialized during server rendering.

Example Scenario:

import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/ui/dialog'

interface ModalProps {
  title: string
  description: string
  isOpen: boolean
  onClose: () => void
}

export const Modal: React.FC<ModalProps> = ({ title, description, isOpen, onClose, children }) => {
  const onChange = (open: boolean) => {
    if (!open) {
      onClose()
    }
  }

  return (
    <Dialog open={isOpen} onOpenChange={onChange}>
      <DialogContent>
        <DialogHeader>
          <DialogTitle>{title}</DialogTitle>
          <p>{description}</p>
        </DialogHeader>
        {children}
      </DialogContent>
    </Dialog>
  )
}

When this Modal component is rendered in a Next.js page, a hydration error may occur because the server and client outputs do not match.

Solutions

1. Delayed Rendering with useEffect

Ensure the dialog is only rendered on the client by delaying its initialization using the useEffect hook.

Updated Code:

import { useState, useEffect } from 'react'

export const Modal: React.FC<ModalProps> = ({ title, description, isOpen, onClose, children }) => {
  const [isMounted, setIsMounted] = useState(false)

  useEffect(() => {
    setIsMounted(true)
  }, [])

  if (!isMounted) {
    return null
  }

  const onChange = (open: boolean) => {
    if (!open) {
      onClose()
    }
  }

  return (
    <Dialog open={isOpen} onOpenChange={onChange}>
      <DialogContent>
        <DialogHeader>
          <DialogTitle>{title}</DialogTitle>
          <p>{description}</p>
        </DialogHeader>
        {children}
      </DialogContent>
    </Dialog>
  )
}

2. Use Dynamic Imports with ssr: false

Another approach is to dynamically import the Modal component and disable server-side rendering (SSR).

Example:

import dynamic from 'next/dynamic'

const Modal = dynamic(() => import('@/components/ui/modal'), {
  ssr: false,
  loading: () => <p>Loading...</p>,
})

const SetupPage = () => {
  return (
    <div className="p-4">
      <Modal title="Test" description="Test Desc" isOpen={true} onClose={() => {}}>
        Children
      </Modal>
    </div>
  )
}

export default SetupPage

3. Adjust Radix UI Settings

If you’re using Radix UI (underlying Shadcn components), ensure proper settings are in place to avoid SSR issues. Radix components often support props like forceMount to control server-side rendering.

Example:

<Dialog open={isOpen} forceMount>
  <DialogContent>...</DialogContent>
</Dialog>

FAQs

1. Why does the hydration error occur? The error occurs because the server-rendered HTML does not match the dynamically rendered content on the client, often due to state or lifecycle discrepancies.

2. Why use useEffect or dynamic imports? These approaches ensure that components relying on client-side state or interactivity are only initialized after the client has loaded, preventing mismatches.

3. Can I use Shadcn Dialog without SSR? Yes, disabling SSR for the component using dynamic imports is a common and effective solution.

Conclusion

By delaying rendering, using dynamic imports, or adjusting Radix UI settings, you can resolve hydration errors with Shadcn Dialog in Next.js. These methods ensure consistent rendering between server and client, providing a seamless user experience.