[gatsby-source-contentful] Some referenced nodes can't be resolved during onCreateNode lifecycle

[osartun]

Preliminary Checks

• This issue is not a duplicate. Before opening a new issue, please search existing issues: https://github.com/gatsbyjs/gatsby/issues
• This issue is not a question, feature request, RFC, or anything other than a bug report. Please post those things in GitHub Discussions: https://github.com/gatsbyjs/gatsby/discussions

Description

We have a local transformer plugin built on top of gatsby-source-contentful which breaks when we update the Contentful plugin. The problem is that getNode(…) returns null for certain referenced nodes even though the nodes exist at the end of the bootstrap process.

The issue didn't exist until 2.1.100. It must have been introduced with #22307 when sourcing nodes was turned asynchronous.

Related links:

• I wrote about my findings in a comment on this issue: getNode returns null on upgrade from gatsby-source-contentful 2.1.88 to 2.2.5 #22792 (comment)
• It's possible that this is the same issue: [gatsby-source-contentful] getNode returns undefined on child node when using latest [email protected] #32290

Reproduction Link

https://github.com/osartun/gatsby-contentful-transformer-issue

Steps to Reproduce

Clone the reproduction repo and run gatsby in the v3 folder. Read more in the README of the reproduction repo.

Alternatively:

1. Use gatsby-source-contentful >= 2.2.0
2. Have a Contentful entry reference another entry of a different content type. (It might be important that the referenced content type was created after your entry)
3. In your gatsby-node.js in the onCreateNode lifecycle call getNode() with the ID of the referenced node

Expected Result

getNode({referenced id}) returns the node

Actual Result

getNode({referenced id}) returns null

Environment

System:
    OS: macOS 11.3.1
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 14.17.1 - ~/.nvm/versions/node/v14.17.1/bin/node
    Yarn: 1.22.10 - ~/.nvm/versions/node/v14.17.1/bin/yarn
    npm: 6.14.13 - ~/.nvm/versions/node/v14.17.1/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 91.0.4472.114
    Firefox: 89.0.1
    Safari: 14.1
  npmPackages:
    gatsby: ^3.9.1 => 3.9.1
    gatsby-plugin-image: ^1.9.0 => 1.9.0
    gatsby-source-contentful: ^5.9.0 => 5.9.0
  npmGlobalPackages:
    gatsby-cli: 3.9.0

Config Flags

No response

[axe312ger]

Thank you for the detailed report. I'll have a look. @wardpeet Seems like your changed introduced the issue, any idea why?

[wardpeet]

My guess is that this was luck that it worked before. The order how we create nodes probably got changed. It's not a good idea to fetch other nodes during onCreateNode call. @osartun I suggest creating a customer resolver instead of adding it as a field to the object.

[osartun]

@wardpeet You mean the createResolvers API? https://www.gatsbyjs.com/docs/reference/graphql-data-layer/schema-customization/#createresolvers-api

[wardpeet]

@osartun https://www.gatsbyjs.com/docs/reference/graphql-data-layer/schema-customization/

this comes closest to what you're looking for
https://www.gatsbyjs.com/docs/reference/graphql-data-layer/schema-customization/#foreign-key-fields