gatsby-node.js

/* Vendor imports */
const path = require('path');
/* App imports */
const config = require('./config');
const utils = require('./src/utils/pageUtils');

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

    return graphql(`
    {
      allMarkdownRemark(sort: {order: DESC, fields: [frontmatter___date]}) {
        edges {
          node {
            frontmatter {
              path
              tags
            }
            fileAbsolutePath
          }
        }
      }
    }    
  `).then((result) => {
        if (result.errors) return Promise.reject(result.errors);

        const {allMarkdownRemark} = result.data;

        /* Post pages */
        allMarkdownRemark.edges.forEach(({node}) => {
            // Check path prefix of post
            if (node.frontmatter.path.indexOf(config.pages.blog) !== 0) {
                // eslint-disable-next-line no-throw-literal
                throw `Invalid path prefix: ${node.frontmatter.path}`;
            }

            createPage({
                path: node.frontmatter.path,
                component: path.resolve('src/templates/post/post.jsx'),
                context: {
                    postPath: node.frontmatter.path,
                    translations: utils.getRelatedTranslations(node, allMarkdownRemark.edges),
                },
            });
        });
        const regexForIndex = /index\.md$/;
        // Posts in default language, excluded the translated versions
        const defaultPosts = allMarkdownRemark.edges
            .filter(({node: {fileAbsolutePath}}) => fileAbsolutePath.match(regexForIndex));

        /* Tag pages */
        const allTags = [];
        defaultPosts.forEach(({node}) => {
            node.frontmatter.tags.forEach((tag) => {
                if (allTags.indexOf(tag) === -1) allTags.push(tag);
            });
        });

        allTags
            .forEach((tag) => {
                createPage({
                    path: utils.resolvePageUrl(config.pages.tag, tag),
                    component: path.resolve('src/templates/tags/index.jsx'),
                    context: {
                        tag,
                    },
                });
            });

        return 1;
    });
};