Support extraction of content on build with onContent function

README.md

@@ -107,6 +107,12 @@ Object of scan objects containing the following parameters
 
 See ["Scanning MDX Content"](#scanning-mdx-content) for more details.
 
+### onContent
+
+> `function` | optional
+
+A function that will run on build for each MDX page. All metadata and full text content are passed to this function as its only argument. Useful for indexing your content for site search or any other purpose where you'd like to capture content on build.
+
 ## Layouts
 
 We can specify a layout for a given `.mdx` file using its front matter, as such:

__tests__/fixtures/on-content/layouts/docs-page.jsx

@@ -0,0 +1,5 @@
+export default () => {
+  return function docsPageLayout({ children }) {
+    return <>{children}</>
+  }
+}

__tests__/fixtures/on-content/next.config-mock.js

@@ -0,0 +1,6 @@
+const withMdxEnhanced = require('../../..')
+
+module.exports = configFn =>
+  withMdxEnhanced({
+    onContent: mdxContent => configFn(mdxContent)
+  })()

__tests__/fixtures/on-content/next.config.js

@@ -0,0 +1,9 @@
+const withMdxEnhanced = require('../../..')
+
+module.exports = withMdxEnhanced({
+  onContent: mdxContent => processContent(mdxContent)
+})()
+
+function processContent(content) {
+  console.log(content)
+}

__tests__/fixtures/on-content/pages/docs/advanced.mdx

@@ -0,0 +1,6 @@
+---
+layout: 'docs-page'
+title: 'Advanced Docs'
+---
+
+A piece of content that should trigger a function call for `onContent`

__tests__/fixtures/on-content/pages/docs/intro.mdx

@@ -0,0 +1,6 @@
+---
+layout: 'docs-page'
+title: 'Intro Docs'
+---
+
+A piece of content that should trigger a function call for `onContent`

__tests__/fixtures/on-content/pages/index.jsx

@@ -0,0 +1 @@
+export default () => <p>Hello world</p>

__tests__/integration.js

@@ -3,6 +3,7 @@ const fs = require('fs')
 const rmfr = require('rmfr')
 const nextBuild = require('next/dist/build').default
 const nextExport = require('next/dist/export').default
+const glob = require('glob')
 
 // increase timeout since these are integration tests
 jest.setTimeout(20000)
@@ -70,6 +71,22 @@ test('options.scan', async () => {
   )
 })
 
+test('options.onContent', async () => {
+  const onContentFixture = path.join(__dirname, 'fixtures/on-content')
+  let mdxPageCount = 0
+  glob('**/**/*.mdx', { cwd: onContentFixture }, (err, files) => {
+    if (err) throw err
+    mdxPageCount = files.length
+  })
+  const mockCallback = jest.fn(content => console.log(content))
+  const compile = await compileNextjsWithMockFunction(
+    onContentFixture,
+    'next.config-mock.js',
+    mockCallback
+  )
+  expect(compile.mock.calls.length).toBe(mdxPageCount)
+})
+
 // Remove artifacts
 afterAll(() => {
   return Promise.all([
@@ -98,3 +115,18 @@ function expectContentMatch(outPath, filePath, matcher) {
   const content = fs.readFileSync(path.join(outPath, filePath), 'utf8')
   return expect(content).toMatch(matcher)
 }
+
+function compileNextjsWithMockFunction(
+  projectPath,
+  configPath = 'next.config.js',
+  mockFn
+) {
+  const config = require(path.join(projectPath, configPath))
+  const outPath = path.join(projectPath, 'out')
+  return nextBuild(projectPath, config(mockFn)).then(() => {
+    return nextExport(projectPath, {
+      outdir: outPath,
+      silent: true
+    }).then(() => mockFn)
+  })
+}

loader.js

@@ -101,9 +101,19 @@ function processLayout(options, frontMatter, content, resourcePath, scans) {
         )
       }
 
+      const { onContent } = pluginOpts
+      if (onContent && this._compiler.name === 'server') {
+        onContent({
+          ...frontMatter,
+          ...extendedFm,
+          ...{ __resourcePath: resourcePath },
+          content
+        })
+      }
+
       // Import the layout, export the layout-wrapped content, pass front matter into layout
       return resolve(`import layout from '${normalizeToUnixPath(layoutPath)}'
-
+      
 export default layout(${stringifyObject({
         ...frontMatter,
         ...extendedFm,