gatsby-node.js

const _ = require('lodash')
const path = require('path')
const { createFilePath } = require('gatsby-source-filesystem')
const { fmImagesToRelative } = require('gatsby-remark-relative-images')
const createPaginatedPages = require('gatsby-paginate')

// Remove trailing slashes unless it's only "/", then leave it as it is
const replaceTrailing = _path => (_path === `/` ? _path : _path.replace(/\/$/, ``))

exports.createPages = ({ actions, graphql }) => {
  const { createPage } = actions

  return graphql(`
    {
      allMarkdownRemark(limit: 1000) {
        edges {
          node {
            id
            fields {
              slug
            }
            frontmatter {
              tags
              templateKey
            }
          }
        }
      }
    }
  `).then(result => {
    if (result.errors) {
      result.errors.forEach(e => console.error(e.toString()))
      return Promise.reject(result.errors)
    }

    const postsAndPages = result.data.allMarkdownRemark.edges
     // Post pages:
     let posts = []
     // Iterate through each post/page, putting all found posts (where templateKey = blog-post) into `posts`
     postsAndPages.forEach(edge => {
       if (_.isMatch(edge.node.frontmatter, { templateKey: 'blog-post' })) {
         posts = posts.concat(edge)
       }
     })

   createPaginatedPages({
       edges: posts,
       createPage: createPage,
       pageTemplate: 'src/pages/blog/index.js',
       pageLength: 10,
       pathPrefix: 'blog',
       context: {
       }
     })

/* 
     Array.from({ length: numPages }).forEach((posts, i) => {
      createPage({
        edges: posts,
        path: i === 0 ? `/` : `/${i + 1}`,
        component: path.resolve("src/pages/blog/index.js"),
        context: {
          limit: postsPerPage,
          skip: i * postsPerPage,
          posts
        }
      })
    }) */


    postsAndPages.forEach(edge => {
      const id = edge.node.id
      createPage({
        path: edge.node.fields.slug,
        tags: edge.node.frontmatter.tags,
        component: path.resolve(
          `src/templates/${String(edge.node.frontmatter.templateKey)}.js`
        ),
        // additional data can be passed via context
        context: {
          id,
        },
      })
    })

    // Tag pages:
    let tags = []
    // Iterate through each post, putting all found tags into `tags`
    postsAndPages.forEach(edge => {
      if (_.get(edge, `node.frontmatter.tags`)) {
        tags = tags.concat(edge.node.frontmatter.tags)
      }
    })
    // Eliminate duplicate tags
    tags = _.uniq(tags)

    // Make tag pages
    tags.forEach(tag => {
      const tagPath = `/tags/${_.kebabCase(tag)}/`

      createPage({
        path: tagPath,
        component: path.resolve(`src/templates/tags.js`),
        context: {
          tag,
        },
      })
    })
  })
}

exports.onCreateNode = ({ node, actions, getNode }) => {
  const { createNodeField } = actions
  fmImagesToRelative(node) // convert image paths for gatsby images

  if (node.internal.type === `MarkdownRemark`) {
    const value = createFilePath({ node, getNode })
    createNodeField({
      name: `slug`,
      node,
      value,
    })
  }
}