ERROR: Cannot read property 'replace' of undefined, onCreateNode, while using contentful cms

[AnnieTaylorCHEN]

Description

Error msg:

 ERROR #11321  PLUGIN

"gatsby-node.js" threw an error while running the onCreateNode lifecycle:

Cannot read property 'replace' of undefined



  TypeError: Cannot read property 'replace' of undefined
  
  - path.js:54 slash
    [PetiteMinimal]/[gatsby-core-utils]/dist/path.js:54:15
  
  - create-file-path.js:41 module.exports
    [PetiteMinimal]/[gatsby-source-filesystem]/create-file-path.js:41:61
  
  - gatsby-node.js:16 Object.exports.onCreateNode
    /home/annie/Desktop/PetiteMinimal/gatsby-node.js:16:18
  
  - api-runner-node.js:235 runAPI
    [PetiteMinimal]/[gatsby]/dist/utils/api-runner-node.js:235:41
  
  - api-runner-node.js:375 Promise.catch.pluginName
    [PetiteMinimal]/[gatsby]/dist/utils/api-runner-node.js:375:13
  
  - new Promise
  
  - api-runner-node.js:374 runPlugin
    [PetiteMinimal]/[gatsby]/dist/utils/api-runner-node.js:374:10
  
  - api-runner-node.js:328 module.exports
    [PetiteMinimal]/[gatsby]/dist/utils/api-runner-node.js:328:24
  
  - task_queues.js:93 processTicksAndRejections
    internal/process/task_queues.js:93:5

I suspect that the errors are caused by onCreateNode in gatsby-node.js file. Because for some reasons I have 49 totalCount in allMarkdownRemark, while I only have 6 md files to create blog posts. Those extra files might come from contentful cms for some reason, they have sourceName and absolutepath as Null, but they do have internal.content, which are some filler text, which appear in some of my contentful data.

When I commented this out, together with blog templates and createPages for blog files, I no longer had the error msg. That's why I suspect it was caused by the those extra files (that is not from my md files) with a lot null fields.

Reference link:
Click here

Steps to reproduce

Almost impossible to reproduce unless you have exactly the same content as my contentful cms.

Expected result

can deploy to netlify.

Actual result

when I run gatsby develop, site is working correctly locally as expected despite the console has errors. And those errors are causing gatsby build to fail, so I can't deploy it.

Environment

System:
OS: Linux 5.0 Linux Mint 19.3 (Tricia)
CPU: (4) x64 Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz
Shell: 4.4.20 - /bin/bash
Binaries:
Node: 12.13.0 - ~/.nvm/versions/node/v12.13.0/bin/node
npm: 6.12.0 - ~/.nvm/versions/node/v12.13.0/bin/npm
Languages:
Python: 2.7.17 - /usr/bin/python
Browsers:
Chrome: 79.0.3945.117
Firefox: 72.0.1
npmPackages:
gatsby: ^2.18.8 => 2.18.11
gatsby-image: ^2.2.34 => 2.2.36
gatsby-plugin-commercelayer: ^1.2.10 => 1.2.10
gatsby-plugin-manifest: ^2.2.31 => 2.2.33
gatsby-plugin-offline: ^3.0.27 => 3.0.29
gatsby-plugin-react-helmet: ^3.1.16 => 3.1.18
gatsby-plugin-sharp: ^2.3.5 => 2.3.7
gatsby-plugin-snipcart: ^1.1.2 => 1.1.2
gatsby-remark-images: ^3.1.38 => 3.1.38
gatsby-remark-source-name: ^1.0.0 => 1.0.0
gatsby-source-contentful: ^2.1.76 => 2.1.76
gatsby-source-filesystem: ^2.1.40 => 2.1.42
gatsby-transformer-remark: ^2.6.42 => 2.6.42
gatsby-transformer-sharp: ^2.3.7 => 2.3.9
npmGlobalPackages:
gatsby-cli: 2.8.26

[AnnieTaylorCHEN]

According to #20398, it seems all the longText from contentful is markdown. This might explains why I have those extra files.

Then.... what should I do with onCreateNode to generate md files for blog posts only?

[LekoArts]

Hi!

Sorry to hear you're running into an issue. To help us best begin debugging the underlying cause, it is incredibly helpful if you're able to create a minimal reproduction. I know that you linked a repository but unfortunately we don't have access to your contentful space. Creating such an example will also help you see at which point the problem occurs.

Then.... what should I do with onCreateNode to generate md files for blog posts only?

You filter for the sourceInstanceName namely blog:

exports.onCreateNode = ({ node, getNode, ...rest }) => {
  const fileNode = getNode(node.parent)
  const source = fileNode.sourceInstanceName

  if (node.internal.type === `MarkdownRemark` && source === 'blog') {}
}

[AnnieTaylorCHEN]

Thank you so much Lennart @LekoArts .

I know a minimal production would be nicer... I will try that next time.

I also tried your code but it resulted in errors which is similar to the above. However, I tried those myself and finally was able to run gatsby build and deployed my site. For future reference here is my code:

exports.onCreateNode = ({ node, getNode, actions }) => {
  const { createNodeField } = actions
  
    if (node.internal.type === "MarkdownRemark" && node.fields.sourceName
     === "blog") {
      const slug = createFilePath({ node, getNode, basePath: "posts" })
      console.log('slug :', slug)
      createNodeField({
        node,
        name: "slug",
        value: slug
      })
    }
    
  }