feat: Build markdown nodes from CMS RichText fields (#98)

* feat: Build markdown nodes for CMS markdown fields

Can be used with MDX

* feat: Add buildMarkdownNodes configuration option

Defaults to false

* style: Linting

* chore(demo): Add MDX dependencies

* chore(demo): Update demo to use MDX

* fix: Remove optional chaining

Eventually transpile with Babel

* docs: Update README to include markdownNode usage

* docs: Add link to demo source

For a full MDX example

demo/gatsby-browser.js

@@ -1,11 +1,17 @@
 import React from 'react'
+import { MDXProvider } from '@mdx-js/react'
 
 import Layout from './src/components/layout'
+import Parargraph from './src/components/paragraph'
 
 import './src/styles/main.css'
 
 const wrapPageElement = ({ element, props }) => {
   return <Layout {...props}>{element}</Layout>
 }
 
-export { wrapPageElement }
+const wrapRootElement = ({ element }) => {
+  return <MDXProvider components={{ p: Parargraph }}>{element}</MDXProvider>
+}
+
+export { wrapPageElement, wrapRootElement }

demo/gatsby-config.js

@@ -2,11 +2,13 @@ require('dotenv').config()
 
 module.exports = {
   plugins: [
+    'gatsby-plugin-mdx',
     'gatsby-plugin-postcss',
     'gatsby-plugin-sharp',
     {
       resolve: 'gatsby-source-graphcms',
       options: {
+        buildMarkdownNodes: true,
         downloadLocalImages: true,
         endpoint: process.env.GRAPHCMS_ENDPOINT,
         token: process.env.GRAPHCMS_TOKEN,

demo/gatsby-node.js

@@ -6,7 +6,11 @@ exports.createPages = async ({ actions: { createPage }, graphql }) => {
       products: allGraphCmsProduct {
         nodes {
           description {
-            text
+            markdownNode {
+              childMdx {
+                body
+              }
+            }
           }
           formattedPrice
           id

demo/gatsby-ssr.js

@@ -1 +1 @@
-export { wrapPageElement } from './gatsby-browser'
+export { wrapPageElement, wrapRootElement } from './gatsby-browser'

demo/package.json

@@ -8,8 +8,11 @@
     "dev": "ENABLE_GATSBY_REFRESH_ENDPOINT=true gatsby develop"
   },
   "dependencies": {
+    "@mdx-js/mdx": "1.6.16",
+    "@mdx-js/react": "1.6.16",
     "gatsby": "2.23.22",
     "gatsby-image": "2.4.13",
+    "gatsby-plugin-mdx": "1.2.30",
     "gatsby-plugin-postcss": "2.3.11",
     "gatsby-plugin-sharp": "2.6.19",
     "gatsby-source-graphcms": "2.0.0",

demo/src/components/paragraph.js

@@ -0,0 +1,7 @@
+import React from 'react'
+
+function Paragraph(props) {
+  return <p className="leading-relaxed md:text-xl text-lg" {...props} />
+}
+
+export default Paragraph

demo/src/templates/product-page.js

@@ -1,6 +1,7 @@
 import React from 'react'
 import { graphql } from 'gatsby'
 import Img from 'gatsby-image'
+import { MDXRenderer } from 'gatsby-plugin-mdx'
 
 const ProductPage = ({ data: { productImages }, pageContext: { product } }) => {
   const [mainImage] = productImages.nodes
@@ -17,9 +18,9 @@ const ProductPage = ({ data: { productImages }, pageContext: { product } }) => {
         {product.description && (
           <React.Fragment>
             <hr className="my-4" />
-            <p className="leading-relaxed md:text-xl text-lg">
-              {product.description.text}
-            </p>
+            <MDXRenderer>
+              {product.description.markdownNode.childMdx.body}
+            </MDXRenderer>
           </React.Fragment>
         )}
       </div>

gatsby-source-graphcms/README.md

@@ -65,6 +65,10 @@ module.exports = {
 
   - Download and cache GraphCMS image assets in your Gatsby project. [Learn more](#downloading-local-image-assets).
 
+- `buldMarkdownNodes` _Boolean_ (default value: `false`)
+
+  - Build markdown nodes for all [`RichText`](https://graphcms.com/docs/reference/fields/rich-text) fields in your GraphCMS schema. [Learn more](#using-markdown-nodes).
+
 ## Downloading local image assets
 
 This source plugin provides the option to download and cache GraphCMS assets in your Gatsby project. This enables you to use [`gatsby-image`](https://www.gatsbyjs.org/packages/gatsby-image), for image loading optimizations, with your GraphCMS image assets.
@@ -107,3 +111,51 @@ You can then use the fragments from [`gatsby-transformer-sharp`](https://www.gat
 ```
 
 For more information on using `gatsby-image`, please see the [documentation](https://www.gatsbyjs.org/packages/gatsby-image/?=#how-to-use).
+
+## Using markdown nodes
+
+This source plugin provides the option to build markdown nodes for all `RichText` fields in your GraphCMS schema, which in turn can be used with [MDX](https://mdxjs.com).
+
+To enable this, add `buildMarkdownNodes: true` to your plugin configuration.
+
+```js
+// gatsby-config.js
+module.exports = {
+  plugins: [
+    {
+      resolve: 'gatsby-source-graphcms',
+      options: {
+        endpoint: process.env.GRAPHCMS_ENDPOINT,
+        buildMarkdownNodes: true,
+      },
+    },
+  ],
+}
+```
+
+Enabling this option adds a `markdownNode` nested field to all `RichText` fields on the generated Gatsby schema.
+
+### Usage with `gatsby-plugin-mdx`
+
+These newly built nodes can be used with [`gatsby-plugin-mdx`](https://www.gatsbyjs.org/packages/gatsby-plugin-mdx) to render markdown from GraphCMS.
+
+Once installed, you will be able to query for `MDX` fields using a query similar to the one below.
+
+```gql
+{
+  allGraphCmsPost {
+    nodes {
+      id
+      content {
+        markdownNode {
+          childMdx {
+            body
+          }
+        }
+      }
+    }
+  }
+}
+```
+
+Check out the [demo source](https://github.com/GraphCMS/gatsby-source-graphcms/tree/next/demo) for an example of a full MDX implementation.

gatsby-source-graphcms/gatsby-node.js

@@ -1,3 +1,4 @@
+const crypto = require('crypto')
 const {
   wrapQueryExecutorWithQueue,
   loadSchema,
@@ -116,7 +117,7 @@ exports.sourceNodes = async (gatsbyApi, pluginOptions) => {
 
 exports.onCreateNode = async (
   { node, actions: { createNode }, createNodeId, getCache },
-  { downloadLocalImages = false }
+  { buildMarkdownNodes = false, downloadLocalImages = false }
 ) => {
   if (
     downloadLocalImages &&
@@ -137,16 +138,54 @@ exports.onCreateNode = async (
       console.error('gatsby-source-graphcms:', e)
     }
   }
+
+  if (buildMarkdownNodes) {
+    const fields = Object.entries(node)
+      .map(([, value]) => value)
+      .filter(
+        (value) =>
+          value && value.remoteTypeName && value.remoteTypeName === 'RichText'
+      )
+
+    if (fields.length) {
+      fields.forEach((field) => {
+        const markdownNode = {
+          id: `MarkdownNode:${createNodeId(node.id)}`,
+          parent: node.id,
+          internal: {
+            type: `GraphCMS_MarkdownNode`,
+            mediaType: 'text/markdown',
+            content: field.markdown,
+            contentDigest: crypto
+              .createHash(`md5`)
+              .update(field.markdown)
+              .digest(`hex`),
+          },
+        }
+
+        createNode(markdownNode)
+
+        field.markdownNode = markdownNode.id
+      })
+    }
+  }
 }
 
 exports.createSchemaCustomization = (
   { actions: { createTypes } },
-  { downloadLocalImages = false }
+  { buildMarkdownNodes = false, downloadLocalImages = false }
 ) => {
   if (downloadLocalImages)
     createTypes(`
-    type GraphCMS_Asset {
-      localFile: File @link
-    }
-  `)
+      type GraphCMS_Asset {
+        localFile: File @link
+      }
+    `)
+
+  if (buildMarkdownNodes)
+    createTypes(`
+      type GraphCMS_RichText {
+        markdownNode: GraphCMS_MarkdownNode @link
+      }
+    `)
 }