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January 5, 2022 01:25 am GMT

Building Dynamic Breadcrumbs in NextJS

Breadcrumbs are a website navigation tool that allows a user to see their current page's "stack" of how it is nested under any parent pages. Users can then jump back to a parent page by clicking the associated breadcrumb link. These "Crumbs" increase User Experience of the application, making it easier for the users to navigate nested pages efficiently and effectively.

Breadcrumbs are popular enough that if you are building a web dashboard or application, you may have considered adding them. Generating these breadcrumb links efficiently and with the appropriate context is key to an improved user experience.

Let's build a smart NextBreadcrumbs React component that will parse the current route and build a dynamic breadcrumbs display that can handle both static & dynamic routes efficiently.

My projects usually revolve around Nextjs and MUI (formerly Material-UI) so that is the angle that I am going to approach this problem from, although the solution should work for any Nextjs-related application.

Static Route Breadcrumbs

To start, our NextBreadcrumbs component will only handle static routes, meaning that our project has only static pages defined in the pages directory.

The following are examples of static routes, because they do not contain [s and ]s in the route names, meaning the directory structure lines up 1:1 exactly with the expected URLs that they serve.

pages/index.js --> /
pages/about.js --> /about
pages/my/super/nested/route.js --> /my/super/nested/route

The solution will be extended to handle dynamic routes later.

Defining the Basic Component

We can start with the basic component that uses the MUI Breadcrumbs component as a baseline.

import Breadcrumbs from '@mui/material/Breadcrumbs';import * as React from 'react';export default function NextBreadcrumbs() {  return (    <Breadcrumbs aria-label="breadcrumb" />  );}

The above creates the basic structure of the NextBreadcrumbs React component, imports the correct dependencies, and renders an empty Breadcrumbs MUI component.

We can then add in the next/router hooks, which will allow us to build the breadcrumbs from the current route.

We also create a Crumb component that will be used to render each link. This is a pretty dumb component for now, except that it will render normal text instead of a link for the last breadcrumb.

In a situation like /settings/notifications, it would render as the following:

Home (/ link) > Settings (/settings link) > Notifications (no link)

This is because the user is already on the last breadcrumb's page, so there is no need to link out to the same page. All the other crumbs are rendered as links to be clicked.

import Breadcrumbs from '@mui/material/Breadcrumbs';import Link from '@mui/material/Link';import Typography from '@mui/material/Typography';import { useRouter } from 'next/router';import React from 'react';export default function NextBreadcrumbs() {  // Gives us ability to load the current route details  const router = useRouter();  return (    <Breadcrumbs aria-label="breadcrumb" />  );}// Each individual "crumb" in the breadcrumbs listfunction Crumb({ text, href, last=false }) {  // The last crumb is rendered as normal text since we are already on the page  if (last) {    return <Typography color="text.primary">{text}</Typography>  }  // All other crumbs will be rendered as links that can be visited   return (    <Link underline="hover" color="inherit" href={href}>      {text}    </Link>  );}

With this layout, we can then dive back into the NextBreadcrumbs component to generate the breadcrumbs from the route. Some existing code will start to be omitted to keep the code pieces smaller. The full example is shown below.

We will generate a list of breadcrumb objects that contain the information to be rendered by each Crumb element. Each breadcrumb will be created by parsing the Nextjs router's asPath property, which is a string containing the route as shown in the browser URL bar.

We will strip any query parameters, such as ?query=value, from the URL to make the breadcrumb creation process more straightforward.

export default function NextBreadcrumbs() {  // Gives us ability to load the current route details  const router = useRouter();  function generateBreadcrumbs() {    // Remove any query parameters, as those aren't included in breadcrumbs    const asPathWithoutQuery = router.asPath.split("?")[0];    // Break down the path between "/"s, removing empty entities    // Ex:"/my/nested/path" --> ["my", "nested", "path"]    const asPathNestedRoutes = asPathWithoutQuery.split("/")                                                 .filter(v => v.length > 0);    // Iterate over the list of nested route parts and build    // a "crumb" object for each one.    const crumblist = asPathParts.map((subpath, idx) => {      // We can get the partial nested route for the crumb      // by joining together the path parts up to this point.      const href = "/" + asPathNestedRoutes.slice(0, idx + 1).join("/");      // The title will just be the route string for now      const title = subpath;      return { href, text };     })    // Add in a default "Home" crumb for the top-level    return [{ href: "/", text: "Home" }, ...crumblist];  }  // Call the function to generate the breadcrumbs list  const breadcrumbs = generateBreadcrumbs();  return (    <Breadcrumbs aria-label="breadcrumb" />  );}

With this list of breadcrumbs, we can now render them using the Breadcrumbs and Crumb components. As previously mentioned, only the return portion of our component is shown for brevity.

  // ...rest of NextBreadcrumbs component above...  return (    {/* The old breadcrumb ending with '/>' was converted into this */}    <Breadcrumbs aria-label="breadcrumb">      {/*        Iterate through the crumbs, and render each individually.        We "mark" the last crumb to not have a link.      */}      {breadcrumbs.map((crumb, idx) => (        <Crumb {...crumb} key={idx} last={idx === breadcrumbs.length - 1} />      ))}    </Breadcrumbs>  );

This should start generating some very basic - but working - breadcrumbs on our site once rendered; /user/settings/notifications would render as

Home > user > settings > notifications

Memoizing Generated Breadcrumbs

There is a quick improvement that we can make before going further though. Right now the breadcrumb list is recreated every time the component re-renders, so we can memoize the crumb list for a given route to save some performance. To accomplish this, we can wrap our generateBreadcrumbs function call in the useMemo React hook.

  const router = useRouter();  // this is the same "generateBreadcrumbs" function, but placed  // inside a "useMemo" call that is dependent on "router.asPath"  const breadcrumbs = React.useMemo(function generateBreadcrumbs() {    const asPathWithoutQuery = router.asPath.split("?")[0];    const asPathNestedRoutes = asPathWithoutQuery.split("/")                                                 .filter(v => v.length > 0);    const crumblist = asPathParts.map((subpath, idx) => {      const href = "/" + asPathNestedRoutes.slice(0, idx + 1).join("/");      return { href, text: subpath };     })    return [{ href: "/", text: "Home" }, ...crumblist];  }, [router.asPath]);  return // ...rest below...

Improving Breadcrumb Text Display

Before we start incorporating dynamic routes, we can clean this current solution up more by including a nice way to change the text shown for each crumb generated.

Right now, if we have a path like /user/settings/notifications, then it will show:

Home > user > settings > notifications

which is not very appealing. We can provide a function to the NextBreadcrumbs component that will try to generate a more user-friendly name for each of these nested route crumbs.

const _defaultGetDefaultTextGenerator= path => pathexport default function NextBreadcrumbs({ getDefaultTextGenerator=_defaultGetDefaultTextGenerator }) {  const router = useRouter();  // Two things of importance:  // 1. The addition of getDefaultTextGenerator in the useMemo dependency list  // 2. getDefaultTextGenerator is now being used for building the text property  const breadcrumbs = React.useMemo(function generateBreadcrumbs() {    const asPathWithoutQuery = router.asPath.split("?")[0];    const asPathNestedRoutes = asPathWithoutQuery.split("/")                                                 .filter(v => v.length > 0);    const crumblist = asPathParts.map((subpath, idx) => {      const href = "/" + asPathNestedRoutes.slice(0, idx + 1).join("/");      return { href, text: getDefaultTextGenerator(subpath, href) };     })    return [{ href: "/", text: "Home" }, ...crumblist];  }, [router.asPath, getDefaultTextGenerator]);  return ( // ...rest below

and then our parent component can have something like the following, to title-ize the subpaths, or maybe even replace them with a new string.

{/* Assume that `titleize` is written and works appropriately */}<NextBreadcrumbs getDefaultTextGenerator={path => titleize(path)} />

This implementation would then result in the following breadcrumbs. The full code example at the bottom has more examples of this.

Home > User > Settings > Notifications

Nextjs Dynamic Routes

Nextjs's router allows for including dynamic routes that uses Pattern Matching to allow for URLs to have slugs, UUIDs, and other dynamic values that will then be passed to your views.

For example, if your Nextjs application has a page component at pages/post/[post_id].js, then the routes /post/1 and /post/abc will match it.

For our breadcrumbs component, we would like to show the name of the associated post instead of just its UUID. This means that the component will need to dynamically look up the post data based on the nested URL route path and regenerate the text of the associated crumb.

Right now, if you visit /post/abc, you would see breadcrumbs that look like

post > abc

but if the post with UUID has a title of My First Post, then we want to change the breadcrumbs to say

post > My First Post

Let's dive into how that can happen using async functions.

Nextjs Router: `asPath` vs `pathname`

The next/router router instance in our code has two useful properties for our NextBreadcrumbs component; asPath and pathname. The router asPath is the URL path as shown directly in the URL bar of the browser. The pathname is a more internal version of the URL that has the dynamic parts of the path replaced with their [parameter] components.

For example, consider the path /post/abc from above.

The asPath would be /post/abc as the URL is shown
The pathname would be /post/[post_id] as our pages directory dictates

We can use these two URL path variants to build a way to dynamically fetch information about the breadcrumb, so we can show more contextually appropriate information to the user.

There is a lot going on below, so please re-read it - and the helpful notes below it - a few times over if needed.

const _defaultGetTextGenerator = (param, query) => null;const _defaultGetDefaultTextGenerator = path => path;// Pulled out the path part breakdown because its// going to be used by both `asPath` and `pathname`const generatePathParts = pathStr => {  const pathWithoutQuery = pathStr.split("?")[0];  return pathWithoutQuery.split("/")                         .filter(v => v.length > 0);}export default function NextBreadcrumbs({  getTextGenerator=_defaultGetTextGenerator,  getDefaultTextGenerator=_defaultGetDefaultTextGenerator}) {  const router = useRouter();  const breadcrumbs = React.useMemo(function generateBreadcrumbs() {    const asPathNestedRoutes = generatePathParts(router.asPath);    const pathnameNestedRoutes = generatePathParts(router.pathname);    const crumblist = asPathParts.map((subpath, idx) => {      // Pull out and convert "[post_id]" into "post_id"      const param = pathnameNestedRoutes[idx].replace("[", "").replace("]", "");      const href = "/" + asPathNestedRoutes.slice(0, idx + 1).join("/");      return {        href, textGenerator: getTextGenerator(param, router.query),        text: getDefaultTextGenerator(subpath, href)      };     })    return [{ href: "/", text: "Home" }, ...crumblist];  }, [router.asPath, router.pathname, router.query, getTextGenerator, getDefaultTextGenerator]);  return ( // ...rest below

The asPath breakdown was moved to a generatePathParts function since the same logic is used for both router.asPath and router.pathname.
Determine the parameter that lines up with the dynamic route value, so abc would result in post_id.
The nested route parameter and all associated query values (router.query) are passed to a provided getTextGenerator which will return either a null value or a Promise response that should return the dynamic string to use in the associated breadcrumb.
The useMemo dependency array has more dependencies added; router.pathname, router.query, and getTextGenerator.

Finally, we need to update the Crumb component to use this textGenerator value if it is provided for the associated crumb object.

function Crumb({ text: defaultText, textGenerator, href, last=false }) {  const [text, setText] = React.useState(defaultText);  useEffect(async () => {    // If `textGenerator` is nonexistent, then don't do anything    if (!Boolean(textGenerator)) { return; }    // Run the text generator and set the text again    const finalText = await textGenerator();    setText(finalText);  }, [textGenerator]);  if (last) {    return <Typography color="text.primary">{text}</Typography>  }  return (    <Link underline="hover" color="inherit" href={href}>      {text}    </Link>  );}

The breadcrumbs can now handle both static routes and dynamic routes cleanly with the potential to display user-friendly values. While the above code is the business logic of the component, this can all be used with a parent component that looks like the final example below.

Full Example

// NextBreadcrumbs.jsconst _defaultGetTextGenerator = (param, query) => null;const _defaultGetDefaultTextGenerator = path => path;// Pulled out the path part breakdown because its// going to be used by both `asPath` and `pathname`const generatePathParts = pathStr => {  const pathWithoutQuery = pathStr.split("?")[0];  return pathWithoutQuery.split("/")                         .filter(v => v.length > 0);}export default function NextBreadcrumbs({  getTextGenerator=_defaultGetTextGenerator,  getDefaultTextGenerator=_defaultGetDefaultTextGenerator}) {  const router = useRouter();  const breadcrumbs = React.useMemo(function generateBreadcrumbs() {    const asPathNestedRoutes = generatePathParts(router.asPath);    const pathnameNestedRoutes = generatePathParts(router.pathname);    const crumblist = asPathParts.map((subpath, idx) => {      // Pull out and convert "[post_id]" into "post_id"      const param = pathnameNestedRoutes[idx].replace("[", "").replace("]", "");      const href = "/" + asPathNestedRoutes.slice(0, idx + 1).join("/");      return {        href, textGenerator: getTextGenerator(param, router.query),        text: getDefaultTextGenerator(subpath, href)      };     })    return [{ href: "/", text: "Home" }, ...crumblist];  }, [router.asPath, router.pathname, router.query, getTextGenerator, getDefaultTextGenerator]);  return (    <Breadcrumbs aria-label="breadcrumb">      {breadcrumbs.map((crumb, idx) => (        <Crumb {...crumb} key={idx} last={idx === breadcrumbs.length - 1} />      ))}    </Breadcrumbs>  );}function Crumb({ text: defaultText, textGenerator, href, last=false }) {  const [text, setText] = React.useState(defaultText);  useEffect(async () => {    // If `textGenerator` is nonexistent, then don't do anything    if (!Boolean(textGenerator)) { return; }    // Run the text generator and set the text again    const finalText = await textGenerator();    setText(finalText);  }, [textGenerator]);  if (last) {    return <Typography color="text.primary">{text}</Typography>  }  return (    <Link underline="hover" color="inherit" href={href}>      {text}    </Link>  );}

and then an example of this NextBreadcrumbs being used can be seen below. Note that useCallback is used to create only one reference to each helper function which will prevent unnecessary re-renders of the breadcrumbs when/if the page layout component re-rendered. You could also move this out to the top-level scope of the file, but I don't like to pollute the global scope like that.

// MyPage.js (Parent Component)import React from 'react';import NextBreadcrumbs from "./NextBreadcrumbs";function MyPageLayout() {  // Either lookup a nice label for the subpath, or just titleize it  const getDefaultTextGenerator = React.useCallback((subpath) => {    return {      "post": "Posts",      "settings": "User Settings",    }[subpath] || titleize(subpath);  }, [])  // Assuming `fetchAPI` loads data from the API and this will use the  // parameter name to determine how to resolve the text. In the example,  // we fetch the post from the API and return it's `title` property  const getTextGenerator = React.useCallback((param, query) => {    return {      "post_id": () => await fetchAPI(`/posts/${query.post_id}/`).title,    }[param];  }, []);  return () {    <div>      {/* ...Whatever else... */}      <NextBreadcrumbs        getDefaultTextGenerator={getDefaultTextGenerator}        getTextGenerator={getTextGenerator}      />      {/* ...Whatever else... */}    </div>  }}

This is one of my more in-depth and technical posts, so I hope you enjoyed it, and please comment or reach out so that I can ensure consistency and correctness. Hopefully this post taught you a few strategies or concepts about Nextjs.

If you liked this or my other posts, please subscribe to my brand new Newsletter for weekly tech updates!

Original Link: https://dev.to/dan_starner/building-dynamic-breadcrumbs-in-nextjs-17oa

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