Dynamic route parameters not being passed correctly

Dynamic route parameters are essential in web development when you need to handle dynamic content based on user input, such as:

• Fetching user profiles (/user/:id)
• Viewing product details (/product/:productId)
• Displaying blog posts (/blog/:slug)

They allow your app to handle different values dynamically without defining static routes for each case.

Common Issues with Dynamic Route Parameters

If your dynamic route parameters are not being passed correctly, the issue could be due to:

1. Incorrect route definitions
2. Improper use of URL parameters
3. Issues with navigation methods
4. Problems in fetching parameters in components
5. Incorrect configurations in frameworks like React, Next.js, Angular, or Express.js

Let’s go through each of these issues and their solutions.

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Step 1: Define Dynamic Routes Properly

First, ensure your route definition is correct. The syntax varies slightly depending on the framework you are using.

Example in Express.js (Backend Route)

app.get('/user/:id', (req, res) => {
    const userId = req.params.id;
    res.send(`User ID is ${userId}`);
});

Here, :id is the dynamic parameter that will be extracted from the request.

Example in React Router (Frontend Route Handling)

<Route path="/user/:id" element={<UserProfile />} />

If the route is incorrect, React Router won’t recognize the parameter correctly.

Common mistakes:

• Using /user/{id} instead of /user/:id
• Forgetting to wrap dynamic segments in <Route path="..." />

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Step 2: Extract Parameters Correctly

Once you have the route defined, you need to extract the parameters properly.

In Express.js Backend

app.get('/user/:id', (req, res) => {
    console.log(req.params); // Should log { id: '123' } if the URL is /user/123
});

If req.params is empty, check:

1. Whether the request is reaching the server
2. If the route path is defined before other conflicting routes
3. If middleware (like body-parser for POST requests) is missing

In React (Using useParams Hook in React Router v6)

import { useParams } from 'react-router-dom';

function UserProfile() {
    let { id } = useParams(); // Extracts dynamic ID from URL
    return <h1>User ID: {id}</h1>;
}

If id is undefined:

1. Ensure <Route path="/user/:id" element={<UserProfile />} /> is correctly defined
2. Check that you’re accessing the route correctly (/user/123)

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Step 3: Use Navigation Correctly

Incorrect navigation can also cause issues.

Example Using React Router’s useNavigate Hook

import { useNavigate } from 'react-router-dom';

function HomePage() {
    let navigate = useNavigate();

    const goToUserProfile = () => {
        navigate(`/user/123`); // Navigates to the correct dynamic route
    };

    return <button onClick={goToUserProfile}>Go to User</button>;
}

Common mistakes:

• Using navigate('/user/{id}') instead of navigate(/user/${id})
• Not wrapping routes inside <BrowserRouter>

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Step 4: Fetching Parameters in API Calls

When making API requests with dynamic parameters, ensure they are passed correctly.

Example Using Fetch API

useEffect(() => {
    fetch(`/api/user/${id}`)
        .then(res => res.json())
        .then(data => setUser(data))
        .catch(err => console.error(err));
}, [id]);

Common errors:

• Using fetch('/api/user/id') instead of fetch(/api/user/${id})
• Forgetting to check if id is undefined before making the API request

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Step 5: Handling Issues in Next.js

In Next.js, dynamic routes are handled differently using file-based routing.

Correct Dynamic Route Setup in Next.js

1. Create a file: pages/user/[id].js
2. Extract the parameter in getServerSideProps or useRouter

import { useRouter } from 'next/router';

const UserProfile = () => {
    const router = useRouter();
    const { id } = router.query;

    return <h1>User ID: {id}</h1>;
};

export default UserProfile;

If id is undefined:

• Make sure you are using the correct dynamic file structure ([id].js)
• Ensure router.query.id is available by wrapping in a useEffect if needed

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Step 6: Debugging Issues

If the parameters are not working:

Check Console Logs

• console.log(req.params); in Express
• console.log(useParams()); in React
• console.log(router.query); in Next.js

Check Network Requests

• Open browser dev tools (F12 → Network tab)
• See if the request is correctly hitting the backend

Check Route Order in Express

• Dynamic routes (/user/:id) should not come after wildcard routes (*)

Check Browser URL

• Ensure you are passing the correct values in the URL (/user/123 and not /user/{id})