gatsby-node.js

const _ = require(`lodash`)
const Promise = require(`bluebird`)
const path = require(`path`)
const slash = require(`slash`)
const webpackLodashPlugin = require('lodash-webpack-plugin')

const { DEPLOY_ENV } = process.env;
/**
 * Generate node edges
 *
 * @param {any} { node, boundActionCreators, getNode }
 */
exports.onCreateNode = ({ node, boundActionCreators }) => {
  const { createNodeField } = boundActionCreators;

  if (!Object.prototype.hasOwnProperty.call(node, 'meta')) {
    return;
  }

  let deploy;

  if (node.meta[DEPLOY_ENV]) {
    deploy = true;
  } else {
    deploy = false;
  }

  createNodeField({ node, name: 'deploy', value: deploy });
};

// Will create pages for Wordpress pages (route : /{slug})
// Will create pages for Wordpress posts (route : /{slug})

exports.createPages = ({ graphql, boundActionCreators }) => {
  const { createPage } = boundActionCreators
  return new Promise((resolve, reject) => {
    // First, query all the pages on your WordPress
    graphql(
      `
        {
          allWordpressPage {
            edges {
              node {
                id
                slug
                status
                template
                fields {
                  deploy
                }
              }
            }
          }
        }
      `
    )
      .then(result => {
        if (result.errors) {
          console.log(result.errors)
          reject(result.errors)
        }
        // Create those pages with the wp_page.jsx template.
        const pageTemplate = path.resolve(`./src/templates/wp_page.jsx`)
        _.each(result.data.allWordpressPage.edges, edge => {
          if (edge.node.fields.deploy) {
            createPage({
              path: `/${edge.node.slug}/`,
              component: slash(pageTemplate),
              context: {
                id: edge.node.id
              }
            })
          }
        })
      })
      // Now, querying all wordpressPosts
      .then(() => {
        graphql(
          `
            {
              allWordpressPost {
                edges {
                  node {
                    id
                    slug
                    modified
                    categories {
                      name
                    }
                    fields {
                      deploy
                    }
                  }
                }
              }
            }
          `
        ).then(result => {
          if (result.errors) {
            console.log(result.errors)
            reject(result.errors)
          }

          const categories = []
          const postTemplate = path.resolve(`./src/templates/post.jsx`)
          // We want to create a detailed page for each
          // post node. We'll just use the Wordpress Slug for the slug.
          // The Post ID is prefixed with 'POST_'

          _.each(result.data.allWordpressPost.edges, edge => {

            if (edge.node.fields.deploy) {
              // grab all the tags and categories for later use
              edge.node.categories.forEach(category => {
                categories.push(category.name)
              })

              createPage({
                path: `/${edge.node.slug}`,
                component: slash(postTemplate),
                context: {
                  id: edge.node.id,
                }
              })
            }

          })
          // ==== END POSTS ====

          // Create pages for each unique category

          const categoriesTemplate = path.resolve(
            `./src/templates/category.jsx`
          )

          const catSet = new Set(categories)

          catSet.forEach(cat => {
            createPage({
              path: `/category/${_.kebabCase(cat)}/`,
              component: slash(categoriesTemplate),
              context: {
                id: cat
              }
            })
          })
          resolve()
        })
      })
    // === END TAGS ===
    resolve()
  })
}

exports.modifyWebpackConfig = ({ config, stage }) => {
  if (stage === 'build-javascript') {
    config.plugin('Lodash', webpackLodashPlugin, null)
  }
}