Gatsby Node API (1/2)

onCreateNode.js

// Defining what should happen whenever we create a new node
exports.onCreateNode = ({ node, getNode, actions }) => {
  const { createNode, createNodeField } = actions
  // Check if the node being passed is the right type (our markdown content)
  if (node.internal.type === 'MarkdownRemark') {
    // Generate a new slug for this file using the createFilePath function
    // Note we are setting the basePath as pages that way the slug will also include subdirectories
    const slug = createFilePath({ node,  getNode , basePath: 'pages'});
    // Add a new field to node of name 'slug' with value slug
    createNodeField({
      node,
      name: `slug`,
      value: slug
    })
  }
}