Unable to use Deferred Static Generation with the Gatsby Source Kontent Plugin

[bwlng]

Brief bug description

Gatsby builds using the new defer argument for the createPage action in gatsby-node.js to exclude the page from the build step and instead generate it during the first HTTP request result in an error during the build process.

During the Validating Rendering Engines portion of the build process, the following error is thrown:

Gatsby kontent source plugin resulted to error in `createSchemaCustomization` method ENOENT: no such file or directory, open '.cache/query-engine/template.items.schema.gql'

Error: ENOENT: no such file or directory, open '.cache/query-engine/template.items.schema.gql'

Repro steps

1. Add the defer argument to a createPage action in gatsby-node.js
2. Run npm run build
3. See error

Expected behavior

The site should build. Remove the defer argument from the createPage action then run npm run build and the site will build as expected.

Test environment

• Gatsby 4.1.5
• Gatsby Source Kontent 8.0.0-beta.1

Additional context

A repo with reproducible steps in the README is available here: https://github.com/bwlng/gatsby-kontent-dsg-issue

[bwlng]

A member of the Gatsby team mentioned the fix may be similar to this issue on gatsby-plugin-loadable-components-ssr: graysonhicks/gatsby-plugin-loadable-components-ssr#46

[Simply007]

A member of the Gatsby team mentioned the fix may be similar to this issue on gatsby-plugin-loadable-components-ssr: graysonhicks/gatsby-plugin-loadable-components-ssr#46

The cause is similar

• for schema customization, I am loading the *.gql files as a template for schema definition https://github.com/Kentico/kontent-gatsby-packages/blob/gatsbyv4-upgrade/packages/gatsby-source-kontent/src/naming.ts#L133

To identify a file, I am using __dirnane to get current folder for the loading the file content - and in build the __dirname is being set to .cache/query-engine

I have placed the debugger to the file loading place in ~\.cache\query-engine\index.js and when the debugger was hit I haven't found template.items.schema.gql file in the issue .cache folder.

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I have reached out to Gatsby devs to get the best practice for the fix.

[Simply007]

@bwlng

Gatsby did not respond yet, but I have tried to rewrite templated files to TS modules and tested it and it looks it works fine.

I have also tried it on your repo and seems fine.

https://www.npmjs.com/package/@kentico/gatsby-source-kontent/v/8.0.0-beta.2

If it is fixed, please close this issue.

[Simply007]

The issue has been resolved and released version 8.0.0-beta.2.

Gatsby team confirmed the fix was correct. It has been also published on the migration guides:

• https://www.gatsbyjs.com/docs/reference/release-notes/migrating-source-plugin-from-v3-to-v4/#the-old-way-4
• https://www.gatsbyjs.com/docs/reference/release-notes/migrating-from-v3-to-v4/#bundling-external-files