next.config.js

const SUMMARY_JSON = require('./content/summary.json')

module.exports = {
  exportPathMap: function() {
    const posts = {}
    const paths = {}
    SUMMARY_JSON.fileMap && Object.keys(SUMMARY_JSON.fileMap)
      .forEach((file) => {
        const fileObj = SUMMARY_JSON.fileMap[file]
        const obj = {}
        if (fileObj.paths) {
          // Handle custom paths / aliases.
          obj.page = '/post'
          obj.query = {
            fullUrl: file.match(/^content(.+)\.json$/)[1]
          }
          fileObj.paths.forEach((path) => {
            paths[path] = obj
          })
        } else if (file.indexOf('content/posts') === 0) {
          // Handle posts.
          const page = file.split('content').join('').split('.json').join('')
          posts[page] = {
            page: '/post',
            query: {
              fullUrl: page
            }
          }
        }
      })

    return Object.assign({}, {
      '/': { page: '/' }
    }, posts, paths) // aliases
  }
}