Gatsby入门指南—添加上一页下一页功能（完结篇）

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const path = require("path");
exports.createPages = ({ actions, graphql }) => {
  const { createPage } = actions
  const blogPostTemplate = path.resolve(`src/templates/blogPost.js`)
  return graphql(`
    {
      allMarkdownRemark {
        edges {
          node {
            frontmatter {
              path,
              title,
              tags
            }
          }
        }
      }
    }
  `).then(result => {
    if (result.errors) {
      return Promise.reject(result.errors)
    }
    const posts = result.data.allMarkdownRemark.edges;
    createTagPages(createPage, posts);
    posts.forEach(({ node }, index) => {
      const path = node.frontmatter.path;
      const title = node.frontmatter.title;
      createPage({
        title,
        path,
        component: blogPostTemplate,
        context: {
          pathSlug: path,
          //这里是新增加的
          prev: index === 0 ? null : posts[index - 1].node,
          next: index === (posts.length - 1) ? null : posts[index + 1].node
        }, // additional data can be passed via context
      })
    })
  })
}

import React from "react"
import { graphql,Link } from 'gatsby'
const Template = ({ data, pageContext }) => {
  const {next,prev} = pageContext;
  const {markdownRemark} = data;
  const title = markdownRemark.frontmatter.title;
  const html = markdownRemark.html;
  return (
​
    <div style={{
      display: 'flex',
      flexDirection: 'column',
      alignItems: 'center'
    }}>
      <h1>{title}</h1>
      <div dangerouslySetInnerHTML={{ __html: html }} />
      
      {next&&<Link to={next.frontmatter.path}>Next</Link>}
      {prev&&<Link to={prev.frontmatter.path}>Prev</Link>}
    </div>
  )
}
​
export const query = graphql`
  query($pathSlug: String!) {
    markdownRemark(frontmatter: { path: { eq: $pathSlug } }) {
      html
      frontmatter {
        date(formatString: "MMMM DD, YYYY")
        path
        title
      }
    }
  }
`
export default Template;