gatsby-node.js

const path = require(`path`)

const makeRequest = (graphql, request) =>
  new Promise((resolve, reject) => {
    // Query for nodes to use in creating pages.
    resolve(
      graphql(request).then(result => {
        if (result.errors) {
          reject(result.errors)
        }
        return result
      })
    )
  })

// Implement the Gatsby API "createPages". This is called once the
// data layer is bootstrapped to let plugins create pages from data.
exports.createPages = ({ actions, graphql }) => {
  const { createPage } = actions

  // Create pages for each blog.
  const getBlog = makeRequest(
    graphql,
    `
   {
     allContentfulBlog (
       sort: { fields: [createdAt], order: DESC }
       filter: {
         node_locale: {eq: "en-US"}},)
     {
       edges {
         node {
           id
           slug
         }
       }
     }
   }
   `
  ).then(result => {
    result.data.allContentfulBlog.edges.forEach(({ node }) => {
      createPage({
        path: `blog/${node.slug}`,
        component: path.resolve(`src/templates/blog.js`),
        context: {
          id: node.id,
        },
      })
    })
  })

  // Create archive page for all blogs, including pagination
  const getArchive = makeRequest(
    graphql,
    `
{
  allContentfulBlog (
    sort: { fields: [createdAt], order: DESC }
    filter: {
      node_locale: {eq: "en-US"}},)
  {
    edges {
      node {
        id
        slug
      }
    }
  }
}
`
  ).then(result => {
    const blogs = result.data.allContentfulBlog.edges
    const blogsPerPage = 9
    const numPages = Math.ceil(blogs.length / blogsPerPage)

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/blog` : `/blog/${i + 1}`,
        component: path.resolve("./src/templates/archive.js"),
        context: {
          limit: blogsPerPage,
          skip: i * blogsPerPage,
          numPages,
          currentPage: i + 1,
        },
      })
    })
  })

  // Create travel category page, including pagination
  const getTravel = makeRequest(
    graphql,
    `
{
  allContentfulBlog(
    sort: {fields: [createdAt], order: DESC}
    filter: {node_locale: {eq: "en-US"}, category: {elemMatch: {title: {eq: "Travel"}}}}
  ) {
    edges {
      node {
        id
        slug
      }
    }
  }
}
`
  ).then(result => {
    const blogs = result.data.allContentfulBlog.edges
    const blogsPerPage = 9
    const numPages = Math.ceil(blogs.length / blogsPerPage)

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/category/travel` : `/category/travel/${i + 1}`,
        component: path.resolve("./src/templates/travel.js"),
        context: {
          limit: blogsPerPage,
          skip: i * blogsPerPage,
          numPages,
          currentPage: i + 1,
        },
      })
    })
  })

  // Create guide category page, including pagination
  const getGuide = makeRequest(
    graphql,
    `
{
  allContentfulBlog(
    sort: {fields: [createdAt], order: DESC}
    filter: {node_locale: {eq: "en-US"}, category: {elemMatch: {title: {eq: "Guide"}}}}
  ) {
    edges {
      node {
        id
        slug
      }
    }
  }
}

`
  ).then(result => {
    const blogs = result.data.allContentfulBlog.edges
    const blogsPerPage = 9
    const numPages = Math.ceil(blogs.length / blogsPerPage)

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/category/guide` : `/category/guide/${i + 1}`,
        component: path.resolve("./src/templates/guide.js"),
        context: {
          limit: blogsPerPage,
          skip: i * blogsPerPage,
          numPages,
          currentPage: i + 1,
        },
      })
    })
  })

  // Create opinion category page, including pagination
  const getOpinion = makeRequest(
    graphql,
    `
{
  allContentfulBlog(
    sort: {fields: [createdAt], order: DESC}
    filter: {node_locale: {eq: "en-US"}, category: {elemMatch: {title: {eq: "Opinion"}}}}
  ) {
    edges {
      node {
        id
        slug
      }
    }
  }
}

`
  ).then(result => {
    const blogs = result.data.allContentfulBlog.edges
    const blogsPerPage = 9
    const numPages = Math.ceil(blogs.length / blogsPerPage)

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/category/opinion` : `/category/opinion/${i + 1}`,
        component: path.resolve("./src/templates/opinion.js"),
        context: {
          limit: blogsPerPage,
          skip: i * blogsPerPage,
          numPages,
          currentPage: i + 1,
        },
      })
    })
  })

  // Create tech category page, including pagination
  const getTech = makeRequest(
    graphql,
    `
{
  allContentfulBlog(
    sort: {fields: [createdAt], order: DESC}
    filter: {node_locale: {eq: "en-US"}, category: {elemMatch: {title: {eq: "Tech"}}}}
  ) {
    edges {
      node {
        id
        slug
      }
    }
  }
}

`
  ).then(result => {
    const blogs = result.data.allContentfulBlog.edges
    const blogsPerPage = 9
    const numPages = Math.ceil(blogs.length / blogsPerPage)

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/category/tech` : `/category/tech/${i + 1}`,
        component: path.resolve("./src/templates/tech.js"),
        context: {
          limit: blogsPerPage,
          skip: i * blogsPerPage,
          numPages,
          currentPage: i + 1,
        },
      })
    })
  })

  return Promise.all([
    getBlog,
    getArchive,
    getTravel,
    getGuide,
    getOpinion,
    getTech,
  ])
}