Next.js: Router.push with state

I'm using next.js for rebuilding an app for server side rendering. I have a button that handles a search request.

In the old app, the handler was this one:

search = (event) => {
    event.preventDefault();
    history.push({
        pathname: '/results',
        state: {
            pattern: this.state.searchText,
        }
    });
}

In the results class, I could get the state date with this.props.location.state.pattern.

So now I'm using next.js:

import Router, { withRouter } from 'next/router'

performSearch = (event) => {
    event.preventDefault();
    Router.push({ pathname: '/results', state: { pattern: this.state.searchText } });
};

In the results class, I use

static async getInitialProps({req}) {
    return req.params;
}

I'm not sure if I have to add this to my server.js:

server.get('/results', (req, res) => {
    return app.render(req, res, '/results', req.params)
})

However, the function getInitialProps throws an error because req is undefined. Long text, short question: how to pass state or params to another page without using GET parameters?

In next.js you can pass query parameters like this

Router.push({
    pathname: '/about',
    query: { name: 'Someone' }
})

and then in your next page (here in /about page), retrieve the query via the router props, which needs to be injected to Component by using withRouter.

import { withRouter } from 'next/router'

class About extends React.Component {
  // your Component implementation
  // retrieve them like this
  // this.props.router.query.name
}

export default withRouter(About)