Path Params

Path params are used to match a single segment (the text until the next /) and provide its value back to you as a named variable. They are defined by using the $ character prefix in the path, followed by the key variable to assign it to. The following are valid path param paths:

• $postId
• $name
• $teamId
• about/$name
• team/$teamId
• blog/$postId

Because path param routes only match to the next /, child routes can be created to continue expressing hierarchy:

Let's create a post route file that uses a path param to match the post ID:

• posts.$postId.tsx

import { createFileRoute } from '@tanstack/react-router'

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    return fetchPost(params.postId)
  },
})

import { createFileRoute } from '@tanstack/react-router'

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    return fetchPost(params.postId)
  },
})

Once a path param has been parsed, it is available to all child routes. This means that if we define a child route to our postRoute, we can use the postId variable from the URL in the child route's path!

Path params are passed to the loader as a params object. The keys of this object are the names of the path params, and the values are the values that were parsed out of the actual URL path. For example, if we were to visit the /blog/123 URL, the params object would be { postId: '123' }:

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    return fetchPost(params.postId)
  },
})

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    return fetchPost(params.postId)
  },
})

The params object is also passed to the beforeLoad option:

export const Route = createFileRoute('/posts/$postId')({
  beforeLoad: async ({ params }) => {
    // do something with params.postId
  },
})

export const Route = createFileRoute('/posts/$postId')({
  beforeLoad: async ({ params }) => {
    // do something with params.postId
  },
})

If we add a component to our postRoute, we can access the postId variable from the URL by using the route's useParams hook:

export const Route = createFileRoute('/posts/$postId')({
  component: PostComponent,
})

function PostComponent() {
  const { postId } = Route.useParams()
  return <div>Post {postId}</div>
}

export const Route = createFileRoute('/posts/$postId')({
  component: PostComponent,
})

function PostComponent() {
  const { postId } = Route.useParams()
  return <div>Post {postId}</div>
}

🧠 Quick tip: If your component is code-split, you can use the getRouteApi function to avoid having to import the Route configuration to get access to the typed useParams() hook.

You can also use the globally exported useParams hook to access any parsed path params from any component in your app. You'll need to pass the strict: false option to useParams, denoting that you want to access the params from an ambiguous location:

function PostComponent() {
  const { postId } = useParams({ strict: false })
  return <div>Post {postId}</div>
}

function PostComponent() {
  const { postId } = useParams({ strict: false })
  return <div>Post {postId}</div>
}

When navigating to a route with path params, TypeScript will require you to pass the params either as an object or as a function that returns an object of params.

Let's see what an object style looks like:

function Component() {
  return (
    <Link to="/blog/$postId" params={{ postId: '123' }}>
      Post 123
    </Link>
  )
}

function Component() {
  return (
    <Link to="/blog/$postId" params={{ postId: '123' }}>
      Post 123
    </Link>
  )
}

And here's what a function style looks like:

function Component() {
  return (
    <Link to="/blog/$postId" params={(prev) => ({ ...prev, postId: '123' })}>
      Post 123
    </Link>
  )
}

function Component() {
  return (
    <Link to="/blog/$postId" params={(prev) => ({ ...prev, postId: '123' })}>
      Post 123
    </Link>
  )
}

Notice that the function style is useful when you need to persist params that are already in the URL for other routes. This is because the function style will receive the current params as an argument, allowing you to modify them as needed and return the final params object.