In NextJs how to change getServerSideProps with change event

Question

Here I am trying to change products data according to category, I have an index page and two components named Products and Categories. At first I am fetching all products by getServerSideProps then I need to fetch category wise products when user selects a category.

Index Page

import Link from 'next/link';
import Layout from '../components/layouts/App';
import Products from '../components/Products';
import Categories from '../components/Categories';
class Index extends React.Component {
    state={
        products:this.props.products,
    }
    
//receiving category id and trying to change state products
    catProducts = async (cat_id) => {
        const res =  await fetch(`https://example.com/get_products?api_key=4e38d8be3269aa17280d0468b89caa4c7d39a699&category_id=${cat_id}`, { method: 'GET' })
        const productsdata =await res.json()    
        console.log(productsdata)
        // this.setState({products: productsdata})
    }

    render() {
        
        return (
            <div>
                <Layout>
                    <div className="main-wrapper pt-35">
                        <div className="row">
                            <div className="col-lg-3">
                                <Categories categories={this.props.categories} catchange={this.catProducts}/>
                            </div>
                            <div className="col-lg-9 order-first order-lg-last">
                                <Products  products={this.state.products} />
                            </div>
                        </div>
                    </div>

                </Layout>
            </div>
        )
    }


}





export async function getServerSideProps() {
    const cats_req = await fetch('https://example.com/api/get_categories?api_key=4e38d8be3269aa17280d0468b89caa4c7d39a699', { method: 'POST' })
    const categories = await cats_req.json();
    const products_req = await fetch(`https://example.com/api/get_products?api_key=4e38d8be3269aa17280d0468b89caa4c7d39a699`, { method: 'GET' })
    const products = await products_req.json();

    return {
        props: {
            products: products,
            categories: categories
        }
    }

}




export default Index

Here I am getting an error Unhandled Runtime Error TypeError: Failed to fetch

I am new to next js so I don't know how to do this, I will appreciate any advice/suggestion

Answer 1

Is the data coming while using getServerSideProps function is the one you want ??

What I can in catProducts is that the URL is not having '/api' in it, whereas in getServerSideProps there is '/api'. It can be one of the reason.

Also Please promise while using fetch.