params vs searchParams

import { notFound } from 'next/navigation'
 
type Props = {
  params: Promise<{ slug: string }>
}
 
// Mock data fetcher
async function getPost(slug: string) {
  const posts: Record<string, { title: string; content: string }> = {
    'hello-world': { title: 'Hello World', content: 'Welcome to our blog!' },
    'nextjs-routing': { title: 'Next.js Routing', content: 'Learn about App Router.' },
  }
  return posts[slug] || null
}
 
export default async function BlogPostPage({ params }: Props) {
  const { slug } = await params
  const post = await getPost(slug)
 
  if (!post) {
    notFound()
  }
 
  return (
    <article className="mx-auto max-w-2xl p-6">
      <h1 className="mb-4 text-3xl font-bold">{post.title}</h1>
      <p className="text-gray-600">{post.content}</p>
    </article>
  )
}

import Link from 'next/link'
import { FilterControls } from './filter-controls'
 
type Props = {
  searchParams: Promise<{
    category?: string
    sort?: string
    page?: string
  }>
}
 
// Mock data
const allPosts = [
  { id: '1', slug: 'hello-world', title: 'Hello World', category: 'general' },
  { id: '2', slug: 'nextjs-routing', title: 'Next.js Routing', category: 'tech' },
  { id: '3', slug: 'react-tips', title: 'React Tips', category: 'tech' },
]
 
export default async function BlogListingPage({ searchParams }: Props) {
  const { category, sort, page } = await searchParams
 
  // Filter and sort posts
  let posts = category
    ? allPosts.filter((p) => p.category === category)
    : allPosts
 
  if (sort === 'title') {
    posts = [...posts].sort((a, b) => a.title.localeCompare(b.title))
  }
 
  const currentPage = parseInt(page || '1', 10)
 
  return (
    <div className="mx-auto max-w-2xl p-6">
      <h1 className="mb-4 text-2xl font-bold">
        Blog Posts {category && <span className="text-gray-500">in {category}</span>}
      </h1>
 
      {/* Client Component for filter controls */}
      <FilterControls currentCategory={category} currentSort={sort} />
 
      <ul className="mt-6 space-y-4">
        {posts.map((post) => (
          <li key={post.id}>
            <Link
              href={`/${post.slug}`}
              className="block rounded-lg border p-4 hover:bg-gray-50"
            >
              <h2 className="font-semibold">{post.title}</h2>
              <span className="text-sm text-gray-500">{post.category}</span>
            </Link>
          </li>
        ))}
      </ul>
 
      <p className="mt-4 text-sm text-gray-500">Page {currentPage}</p>
    </div>
  )
}

'use client'
 
import { useSearchParams, useRouter, usePathname } from 'next/navigation'
import { useCallback } from 'react'
 
type Props = {
  currentCategory?: string
  currentSort?: string
}
 
export function FilterControls({ currentCategory, currentSort }: Props) {
  const router = useRouter()
  const pathname = usePathname()
  const searchParams = useSearchParams()
 
  // Create a new URLSearchParams instance preserving existing params
  const createQueryString = useCallback(
    (name: string, value: string) => {
      const params = new URLSearchParams(searchParams.toString())
      if (value) {
        params.set(name, value)
      } else {
        params.delete(name)
      }
      // Reset pagination when filters change
      if (name !== 'page') {
        params.delete('page')
      }
      return params.toString()
    },
    [searchParams]
  )
 
  const handleCategoryChange = (category: string) => {
    router.push(`${pathname}?${createQueryString('category', category)}`)
  }
 
  const handleSortChange = (sort: string) => {
    router.push(`${pathname}?${createQueryString('sort', sort)}`)
  }
 
  const clearFilters = () => {
    router.push(pathname)
  }
 
  return (
    <div className="flex flex-wrap gap-4">
      {/* Category filter */}
      <div className="flex gap-2">
        <button
          type="button"
          onClick={() => handleCategoryChange('')}
          className={`rounded px-3 py-1 text-sm ${
            !currentCategory ? 'bg-blue-600 text-white' : 'bg-gray-100'
          }`}
        >
          All
        </button>
        <button
          type="button"
          onClick={() => handleCategoryChange('tech')}
          className={`rounded px-3 py-1 text-sm ${
            currentCategory === 'tech' ? 'bg-blue-600 text-white' : 'bg-gray-100'
          }`}
        >
          Tech
        </button>
        <button
          type="button"
          onClick={() => handleCategoryChange('general')}
          className={`rounded px-3 py-1 text-sm ${
            currentCategory === 'general' ? 'bg-blue-600 text-white' : 'bg-gray-100'
          }`}
        >
          General
        </button>
      </div>
 
      {/* Sort control */}
      <select
        value={currentSort || ''}
        onChange={(e) => handleSortChange(e.target.value)}
        className="rounded border px-3 py-1 text-sm"
      >
        <option value="">Default order</option>
        <option value="title">Sort by title</option>
      </select>
 
      {/* Clear all filters */}
      {(currentCategory || currentSort) && (
        <button
          type="button"
          onClick={clearFilters}
          className="text-sm text-red-600 hover:underline"
        >
          Clear filters
        </button>
      )}
    </div>
  )
}