text: const {createFilePath} = require("gatsby-source-filesystem");
  const path = require("path");
  
  exports.onCreateNode = ({ node , getNode, actions }) => {
      const {createNodeField} = actions;
  if (node.internal.type === "MarkdownRemark"){
          const slug = createFilePath({node, getNode, basePath: "posts"})
          createNodeField({
              node, 
              name: "slug",
              value: slug
          })
      }
  }
  
  exports.createPages = ({graphql, actions}) => {
      const {createPage} = actions;
      
      return graphql(`{
          allMarkdownRemark{
            nodes{
              fields{
                slug
              }
            }
          }
        }
      `).then(result=>{
          result.data.allMarkdownRemark.nodes.forEach((node)=>{
              createPage({
                  path: node.fields.slug,
                  component: path.
              })
          })
      })
  }