gatsby-node.js

const path = require('path');
module.exports.onCreateNode = ({ node, actions }) => {
    const { createNodeField } = actions;
    if (node.internal.type === "MarkdownRemark") {
        const slug = path.basename(node.fileAbsolutePath, '.md');
        createNodeField({
            node,
            name: 'slug',
            value: slug
        })
    }

}

module.exports.createPages = async ({ graphql, actions }) => {
    const { createPage } = actions;
    const blogTemplate = path.resolve('./src/templates/blog.js');
    const res = await graphql(`
    query{
        allMarkdownRemark{
            edges{
                node{
                    fields{
                        slug
                    }
                }
            }
        }
    }`)
    res.data.allMarkdownRemark.edges.forEach((edge) => {
        createPage({
            component: blogTemplate,
            path: `/blog/${edge.node.fields.slug}`,
            context: {
                slug: edge.node.fields.slug
            }
        })
    })
    // 1.TODO: Get path to template
    // 1. TODO: Get markdown data
    // 1. TODO: Create new pages

}