Ghost/core/server/services/routing/PreviewRouter.js

const ParentRouter = require('./ParentRouter');
const urlService = require('../url');
const controllers = require('./controllers');

class PreviewRouter extends ParentRouter {
    constructor() {
        super('PreviewRouter');

        this.route = {value: '/p/'};

        this._registerRoutes();
    }

    _registerRoutes() {
        this.router().use(this._prepareContext.bind(this));

        this.mountRoute(urlService.utils.urlJoin(this.route.value, ':uuid', ':options?'), controllers.preview);
    }

    _prepareContext(req, res, next) {
        res.routerOptions = {
            type: 'entry',
            query: {
                alias: 'preview',
                resource: 'posts'
            }
        };

        next();
    }
}

module.exports = PreviewRouter;