BREAKING CHANGE(gatsby-plugin-mdx): MDX v2 (#35650)

Co-authored-by: Josh Johnson <jcjohnson77@gmail.com>
Co-authored-by: LekoArts <lekoarts@gmail.com>
Co-authored-by: Ward Peeters <ward@coding-tech.com>
Co-authored-by: Lennart <lekoarts@gmail.com>
Co-authored-by: pieh <misiek.piechowiak@gmail.com>
Co-authored-by: Michal Piechowiak <misiek.piechowiak@gmail.com>

.circleci/config.yml

@@ -434,15 +434,12 @@ jobs:
           test_path: e2e-tests/themes
           test_command: cd production-runtime; yarn test
 
-  mdx_e2e_tests:
+  e2e_tests_mdx:
     <<: *e2e-executor
     steps:
       - e2e-test:
           test_path: e2e-tests/mdx
           test_command: CYPRESS_PROJECT_ID=spbj28 CYPRESS_RECORD_KEY=af30ea46-121f-4fb7-97dd-f17ec224402e yarn test
-      - e2e-test:
-          test_path: e2e-tests/mdx-less-babel
-          test_command: CYPRESS_PROJECT_ID=xo139a CYPRESS_RECORD_KEY=74d485b5-3ba6-40e1-a7d4-e63c0a8d2a4d yarn test
 
   e2e_tests_visual-regression:
     <<: *e2e-executor
@@ -646,6 +643,8 @@ workflows:
           <<: *e2e-test-workflow
       - e2e_tests_contentful:
           <<: *e2e-test-workflow
+      - e2e_tests_mdx:
+          <<: *e2e-test-workflow
       - e2e_tests_trailing-slash:
           <<: *e2e-test-workflow
       - e2e_tests_development_runtime:
@@ -660,8 +659,6 @@ workflows:
           <<: *e2e-test-workflow
       - themes_e2e_tests_development_runtime:
           <<: *e2e-test-workflow
-      - mdx_e2e_tests:
-          <<: *e2e-test-workflow
       - starters_validate:
           <<: *ignore_master
       - starters_publish:

benchmarks/gabe-fs-mdx/gatsby-config.js

@@ -1,3 +1,5 @@
+const path = require("path")
+
 module.exports = {
   siteMetadata: {
     siteTitle: `Gatsby MDX Benchmark`,
@@ -12,9 +14,7 @@ module.exports = {
     },
     {
       resolve: `gatsby-plugin-mdx`,
-      options: {
-        lessBabel: true,
-      },
     },
-  ],
+    !process.env.CI && `gatsby-plugin-webpack-bundle-analyser-v2`,
+  ].filter(Boolean),
 }

benchmarks/gabe-fs-mdx/gatsby-node.js

@@ -1,7 +1,5 @@
 const path = require("path")
 
-const blogPost = path.resolve(`./src/templates/blog-post.js`)
-
 exports.createPages = async ({ graphql, actions }) => {
   const { createPage } = actions
 
@@ -14,6 +12,13 @@ exports.createPages = async ({ graphql, actions }) => {
           frontmatter {
             title # used in prev/next
           }
+          parent {
+            ... on File {
+              id
+              name
+              absolutePath
+            }
+          }
         }
       }
     }
@@ -25,13 +30,15 @@ exports.createPages = async ({ graphql, actions }) => {
 
   const posts = result.data.allMdx.nodes
 
-  posts.forEach(({ id, slug }, index) => {
+  posts.forEach(({ id, slug, parent }, index) => {
     const previous = index === posts.length - 1 ? null : posts[index + 1]
     const next = index === 0 ? null : posts[index - 1]
 
     createPage({
       path: slug,
-      component: blogPost,
+      component: `${path.resolve(
+        `./src/templates/blog-post.js`
+      )}?__contentFilePath=${parent.absolutePath}`,
       context: {
         id,
         slug,

benchmarks/gabe-fs-mdx/gen.js

@@ -19,7 +19,6 @@ date: ${faker.date.recent(1000).toISOString().slice(0, 10)}
 import { Link } from "gatsby"
 
 export const author = "Fred Flintstone"
-export default props => <main {...props} />
 
 <Link to="/">Go Home</Link>
 

benchmarks/gabe-fs-mdx/package.json

@@ -13,6 +13,7 @@
     "format": "prettier --write \"**/*.{js,jsx,json,md}\""
   },
   "devDependencies": {
+    "gatsby-plugin-webpack-bundle-analyser-v2": "^1.1.27",
     "prettier": "2.0.4"
   },
   "repository": {
@@ -28,13 +29,12 @@
     "mdx"
   ],
   "dependencies": {
-    "@mdx-js/mdx": "^1",
-    "@mdx-js/react": "^1",
+    "@mdx-js/react": "^2",
     "faker": "^4.1.0",
-    "gatsby": "^2",
-    "gatsby-plugin-mdx": "^1",
-    "gatsby-source-filesystem": "^2",
-    "react": "^16.12.0",
-    "react-dom": "^16.12.0"
+    "gatsby": "^4",
+    "gatsby-plugin-mdx": "^3",
+    "gatsby-source-filesystem": "^4",
+    "react": "^17",
+    "react-dom": "^17"
   }
 }

benchmarks/gabe-fs-mdx/src/templates/blog-post.js

@@ -1,29 +1,23 @@
 import React from "react"
 import { graphql, Link } from "gatsby"
 import Layout from "../components/layout_1"
-import { MDXRenderer } from "gatsby-plugin-mdx"
-
-const Article = ({ data }) => {
-  const { body } = data.mdx
-  const { mdx } = data
 
+const Article = ({ children, data: { mdx } }) => {
   return (
     <Layout>
       <Link to="/">Go back to index page</Link>
       <div>
         <h1>{mdx.frontmatter.title}</h1>
-        <div>
-          <MDXRenderer>{body}</MDXRenderer>
-        </div>
+        {children}
       </div>
     </Layout>
   )
 }
 
-export const query = graphql`
-  query MdxQuery($id: String!) {
+export const pageQuery = graphql`
+  query($id: String!) {
     mdx(id: { eq: $id }) {
-      body
+      id
       frontmatter {
         title
       }

docs/docs/how-to/routing/mdx.md

@@ -2,7 +2,7 @@
 title: Add components to content using MDX
 examples:
   - label: Using MDX
-    href: "https://github.com/gatsbyjs/gatsby/tree/master/examples/using-MDX"
+    href: "https://github.com/gatsbyjs/gatsby/tree/master/examples/using-mdx"
 ---
 
 ## Introduction

docs/docs/mdx/importing-and-using-components.md

@@ -119,4 +119,4 @@ Here is a demo:
 
 ### Additional resources
 
-- Follow this detailed [example on using MDX](https://github.com/gatsbyjs/gatsby/tree/master/examples/using-MDX) to import and render components.
+- Follow this detailed [example on using MDX](https://github.com/gatsbyjs/gatsby/tree/master/examples/using-mdx) to import and render components.

docs/docs/reference/graphql-data-layer/schema-customization.md

@@ -131,7 +131,7 @@ suddenly fail.
 Both problems can be solved by providing explicit type definitions for Gatsby's
 GraphQL schema.
 
-### Creating type definitions
+## Creating type definitions
 
 Look at the latter case first. Assume a new author joins the team, but in the
 new author entry there is a typo on the `joinedAt` field: "201-04-02" which is
@@ -150,7 +150,7 @@ not a valid Date.
 This will confuse Gatsby's type inference since the `joinedAt`
 field will now have both Date and String values.
 
-#### Fixing field types
+### Fixing field types
 
 To ensure that the field will always be of Date type, you can provide explicit
 type definitions to Gatsby with the [`createTypes`](/docs/reference/config-files/actions/#createTypes) action.
@@ -176,7 +176,7 @@ provided, they will still be handled by Gatsby's type inference.
 > (available in Gatsby v2.12 and above),
 > and [`sourceNodes`](/docs/reference/config-files/gatsby-node/#sourceNodes) APIs.
 
-#### Opting out of type inference
+### Opting out of type inference
 
 There are however advantages to providing full definitions for a node type, and
 bypassing the type inference mechanism altogether. With smaller scale projects
@@ -209,7 +209,7 @@ Note that you don't need to explicitly provide the Node interface fields (`id`,
 > [specifying nullability](https://graphql.org/learn/schema/#lists-and-non-null)
 > in GraphQL, i.e. if a field value is allowed to be `null` or not.
 
-#### Defining media types
+### Defining media types
 
 You can specify the media types handled by a node type using the `@mimeTypes` extension:
 
@@ -222,7 +222,7 @@ type Markdown implements Node
 
 The types passed in are used to determine child relations of the node.
 
-#### Defining child relations
+### Defining child relations
 
 The `@childOf` extension can be used to explicitly define what node types or media types a node is a child of and immediately add `child[MyType]` and `children[MyType]` fields on the parent.
 
@@ -255,7 +255,7 @@ type Mdx implements Node
 }
 ```
 
-#### Nested types
+### Nested types
 
 So far, the example project has only been dealing with scalar values (`String` and `Date`;
 GraphQL also knows `ID`, `Int`, `Float`, `Boolean` and `JSON`). Fields can
@@ -305,7 +305,7 @@ always starting from the Node types created by source and transformer plugins.
 > it is not a top-level type created by source or transformer plugins: it has no
 > `id` field, and is there to describe the data shape on a nested field.
 
-#### Gatsby Type Builders
+### Gatsby Type Builders
 
 In many cases, GraphQL SDL provides a succinct way to provide type definitions
 for your schema. If however you need more flexibility, `createTypes` also
@@ -362,7 +362,7 @@ schema.buildObjectType({
 > Note that the `createTypes` action also accepts `graphql-js` types directly,
 > but usually either SDL or Type Builders are the better alternatives.
 
-#### Foreign-key fields
+### Foreign-key fields
 
 In the example project, the `frontmatter.author` field on
 `MarkdownRemark` nodes to expand the provided field value to a full `AuthorJson` node.
@@ -466,15 +466,15 @@ For the above example you can read `@link` this way: Use the value from the fiel
 
 Keep in mind that in the example above, the link of `posts` in `AuthorJson` works because `frontmatter` and `author` are both objects. If, for example, the `Frontmatter` type had a list of `authors` instead (`frontmatter.authors.email`), it wouldn't work since the `by` argument doesn't support arrays. In that case, you'd have to provide a custom resolver with [Gatsby Type Builders](/docs/reference/graphql-data-layer/schema-customization/#gatsby-type-builders) or [createResolvers API](/docs/reference/graphql-data-layer/schema-customization/#createresolvers-api).
 
-#### Extensions and directives
+### Extensions and directives
 
-Out of the box, Gatsby provides [four extensions](/docs/reference/config-files/actions/#createTypes)
-that allow adding custom functionality to fields without having to manually
-write field resolvers: the `link` extension has already been discussed above,
-`dateformat` allows adding date formatting options, `fileByRelativePath` is
-similar to `link` but will resolve relative paths when linking to `File` nodes,
-and `proxy` is helpful when dealing with data that contains field names with
-characters that are invalid in GraphQL.
+Out of the box, Gatsby provides [four extensions](/docs/reference/config-files/actions/#createTypes) that allow adding custom functionality to fields without having to manually write field resolvers:
+
+1. The `link` extension has already been discussed above
+1. `dateformat` allows adding date formatting options
+1. `fileByRelativePath` is similar to `link` but will resolve relative paths when linking to `File` nodes
+1. `proxy` is helpful when dealing with data that contains field names with
+   characters that are invalid in GraphQL or to alias fields
 
 To add an extension to a field you can either use a directive in SDL, or the
 `extensions` property when using Gatsby Type Builders:
@@ -518,7 +518,75 @@ query {
 `publishedAt` is also provided a default `formatString` which will be used
 when no explicit formatting options are provided in the query.
 
-#### Setting default field values
+If the JSON would contain keys you'd want to `proxy` to other names, you could do it like this:
+
+```json
+{
+  "name": "Doe",
+  "firstName": "Zoe",
+  "email": "zoe@example.com",
+  "start_date": "2022/08/01"
+}
+```
+
+```graphql
+type AuthorJson implements Node {
+  startDate: Date! @dateformat @proxy(from: "start_date")
+}
+```
+
+You can also combine multiple extensions (built-in and custom ones).
+
+#### Aliasing fields
+
+You can use the `@proxy` directive to alias (nested) fields to another field on the same node. This is helpful if e.g. you want to keep the shape you have to query flat or if you need it to keep things backwards compatible.
+
+If you'd add a new field using [`createNodeField`](/docs/reference/config-files/actions/#createNodeField) to the `MarkdownRemark` nodes (change this check if you use another source/type) like this:
+
+```js:title=gatsby-node.js
+exports.onCreateNode = ({ node, actions }) => {
+  const { createNodeField } = actions
+  if (node.internal.type === `MarkdownRemark`) {
+    createNodeField({
+      node,
+      name: `someInformation`,
+      value: `Hello World`
+    })
+  }
+}
+```
+
+The `Hello World` would be queryable at:
+
+```graphql
+nodes {
+  fields {
+    someInformation
+  }
+}
+```
+
+To be able to query `someInformation` like this instead you have to alias the `fields.someInformation` field.
+
+```graphql
+nodes {
+  someInformation
+}
+```
+
+```javascript:title=source-plugin/gatsby-node.js
+exports.createSchemaCustomization = ({ actions }) => {
+  const { createTypes } = actions
+
+  createTypes(`
+    type MarkdownRemark implements Node {
+      someInformation: String @proxy(from: "fields.someInformation")
+    }
+  `)
+}
+```
+
+### Setting default field values
 
 For setting default field values, Gatsby currently does not (yet) provide an
 out-of-the-box extension, so resolving a field to a default value (instead of
@@ -552,7 +620,7 @@ exports.createSchemaCustomization = ({ actions, schema }) => {
 }
 ```
 
-#### Creating custom extensions
+### Creating custom extensions
 
 With the [`createFieldExtension`](/docs/reference/config-files/actions/#createFieldExtension) action
 it is possible to define custom extensions as a way to add reusable functionality