Generating a Netlify Redirects file from redirect-directives created in Sanity.io

gatsby-node.js

exports.onPostBuild = ({ graphql }) =>
  graphql(`
    {
      redirects: allSanityRedirect {
        nodes {
          matchPath
          target
          statusCode
        }
      }
    }
  `).then(({ data }) => {
    const redirectData = data.redirects.nodes
      .map(
        ({ matchPath, target, statusCode }) =>
          `${matchPath} ${target} ${statusCode}`
      )
      .join("\n")

    return fs.appendFile(
      path.resolve(__dirname, "public/_redirects"),
      redirectData
    )
  })

redirect.js

export default {
  title: "Redirect",
  name: "redirect",
  type: "document",
  fields: [
    {
      title: "Internal Name",
      name: "internalName",
      type: "string",
      validation: Rule => Rule.required(),
    },
    {
      title: "Match Rule",
      description:
        "The URL path to match. This is the “from” portion of the redirect. A “splat” (*) can be used to match any additional characters at the end of the line (e.g. `/blog/*`).",
      name: "rule",
      type: "string",
      validation: Rule =>
        Rule.required().regex(/^\//, { name: "Must start with a `/`" }),
    },
    {
      title: "Redirect Target",
      description:
        "The destination for the redirect. If a “splat” (*) was used in the match rule, it can be expanded in the target using `:splat` (e.g. `/blog/:splat`).",
      name: "target",
      type: "string",
      validation: Rule => Rule.required().regex(/^(\/|https?:\/\/)/),
    },
    {
      title: "Redirect Type",
      description:
        "Both temporary and permanent redirects can be internal or external links. Rewrites can only be internal (i.e. to another page that is built in Sanity).",
      name: "statusCode",
      type: "string",
      options: {
        list: [
          { title: "Temporary (302)", value: "302" },
          { title: "Permanent (301)", value: "301" },
          { title: "Rewrite (200)", value: "200" },
        ],
      },
      validation: Rule => Rule.required(),
    },
  ],
  preview: {
    select: {
      title: "internalName",
      rule: "rule",
      target: "target",
      statusCode: "statusCode",
    },
    prepare: ({ title, rule, target, statusCode }) => ({
      title,
      subtitle: `${rule} ${target} ${statusCode}`,
    }),
  },
}