Gatsby: Add createContentDigest helper

Created on 27 Sep 2018 · 4Comments · Source: gatsbyjs/gatsby

Summary

Add a createContentDigest helper and pass it in to the Gatsby API runner. This means people can use it when implementing Gatsby APIS in their gatsby-node.js file.

Basic example

Create this file packages/gatsby/utils/create-content-digest.js, and add content a bit like:

const crypto = require(`crypto`)

// docblock goes here
const createContentDigest = obj => crypto
  .createHash(`md5`)
  .update(obj)
  .digest(`hex`)


module.exports = createContentDigest

Add a couple of tests to packages/gatsby/utils/__tests__
Import and include the helper here: https://github.com/gatsbyjs/gatsby/blob/17b9dc2b2d3a11ff2663832a6df417af59db5944/packages/gatsby/src/utils/api-runner-node.js#L110 (see createNodeId for an existing example).
Update docs and examples where necessary. Key docs would be the tutorial, the API reference docs and the source plugin guide. Search across the repo for crypto for other places this could be updated. Here's a before and after example of the sourceNodes docs

- const crypto = require(`crypto`);
- 
- exports.sourceNodes = ({ actions, createNodeId }) => {
+ exports.sourceNodes = ({ actions, createNodeId, createContentDigest }) => {
  const { createNode } = actions;
  const myData = {
    foo: `The foo field of my node`,
    bar: `Bar bah baa baw`
  }

  const nodeContent = JSON.stringify(myData)
-    const nodeContentDigest = crypto
-    .createHash(`md5`)
-    .update(nodeContent)
-    .digest(`hex`)

  const nodeMeta = {
    id: createNodeId(`my-unique-id`),
    parent: null,
    children: [],
    internal: {
        type: `MyNodeType`,
        mediaType: `text/html`,
        content: nodeContent,
-        contentDigest: nodeContentDigest
+        contentDigest: createContentDigest(nodeContent)
    }
}

  const node = Object.assign({}, myData, nodeMeta)
  const createNode(node)
}

Ref: https://github.com/gatsbyjs/gatsby/pull/8585/files#r220931791