Is it possible to use the action "createNodeField" from "sourceNodes" API?

I have a use case where I want to add information from the last commit that affected a sourced markdown file. To do this I need to fetch the git information by traversing the git history, but to avoid traversing the same history multiple times, I need to know all files for which I need to fetch the git information first, and then traverse the history only once.

To do this I tried to put my logic in “sourceNodes” like this:

// Get all markdown nodes
let mdNodes = getNodes().filter((node) => node.absolutePath && node.absolutePath.endsWith(".md"));

let gitCache = ... code to build git-cache

mdNodes.forEach(n => {
   createNodeField({
      n,
      name: 'git',
      value: gitCache.getLatestCommitInfo(n.absolutePath) //Gives last commit info for given markdown file
});

When executing the code I get this error: TypeError: Cannot read property 'internal' of undefined

In the documentation I can´t see anywhere that the “createNodeField” should not be working from “sourceNodes”.

[jlkiri]

@david-nossebro I’m looking at a signature of createNodeField and it looks like this:

  { node, name, value, fieldName, fieldValue }: CreateNodeInput,
  plugin: Plugin,
  actionOptions?: ActionOptions

Internally it tries to access internal property of the destructured node but there is no node, there is n instead. Which means that you cannot use n, but node: n instead. Does it fix your issue?

[LekoArts]

Yeah, that’s what I meant. In theory getNodes() should already work (see: https://www.gatsbyjs.org/docs/gatsby-repl/#getnodes) but somehow your n seems undefined as createNodeField tries to access node.internal.type.