CTF-next: Generate GraphQL schema based on Contentful Content Types

[axe312ger]

Discussion for the upcoming major release: #38585

Note for reviewers:

• Follow up to feat(gatsby-source-contentful): provide gql type definitions using content model introspection and schema-customization #12816 and will be a breaking, so major release.
• This branch will not be directly merged into master as some follow up PRs will come to add more features. See CTF-v6: ☂️ Umbrella issue for next major version of gatsby-source-contentful #31385
• The schema.sql for the Contentful e2e test page has about 80 additions and over 300 deletions

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This adds schema generation to the gatsby-source-contentful plugin. This will remove the most annoying restriction of the plugin: You now can have fields without a single instance in your content model and your GraphQL will no more fail because of this. See: https://www.gatsbyjs.com/plugins/gatsby-source-contentful/#restrictions-and-limitations

Goals

• types will be generated based on the content model in Contentful. Your project will no more break when a field has no values at all.
• Contentful Rich Text references will always be available and allow __typename and contentful on root level
• JSON fields are now real GraphQL JSON fields. This avoids the There are conflicting field types in your data. warning and allows the JSON data structure to be changed in Contentful without breaking the Gatsby GraphQL Query
• Create child nodes only when really necessary
  • RichText fields now use a simple object type
  • Location fields now use a simple object type
  • (Long) Text fields still use a node yet, as gatsby-transformer-remark relies on it. Lets discuss later on.
• Keep data from Contentfuls Common resource attributes within the sys property (solved in refactor: reintroduce contentful sys commen resource attribute #31007)
• Current state does break warm builds. I need to have a another look at reference resolver (solved in refactor: reintroduce contentful sys commen resource attribute #31007)
• Overall align the schema closer to the GraphQL Content API (first steps in refactor: reintroduce contentful sys commen resource attribute #31007)
  • Assets should have meta data like width on top level (refactor: flatten Contentful asset data structure to match GraphQL API schema #31115)
  • Rich Text fields split up references in entries and assets (refactor: align Rich Text field structure to Contentful GraphQL API #31122)
• Rename internal types with a scheme that avoids name collisions with content type names (CTF-v6: Rename schema types #31286)
• update e2e-test/contentful (first steps in refactor: reintroduce contentful sys commen resource attribute #31007)
• update gatsby-remark-images-contentful to match new asset structure no changes needed
• update gatsby-transformer-sqip to match new asset structure (as it is part of e2e-test/contentful)
• the tags feature is now enabled by default
• CTF-next: use union for reference fields with validation #31395
• The id generation is now done with two functions which slightly differ. This creates issues with references. WIP fix in https://github.com/gatsbyjs/gatsby/tree/feat/contentful-schema-generation-normalize-id-generation

Performance improvements

• These changes will reduce the node count which will lead to improvements in bigger projects.
• Rich Text fields no more need to JSON.stringify() and rich text renderer no more needs to JSON.parse()

Upcoming goals in the next major / Follow up PRs:

See #31385

Migration steps / Breaking changes

See #31385 (comment) for the full list of steps to migrate.

[itwasmattgregg]

What do you think about adding a metadata: { ...assetItem.metadata }, to const assetNode?

Or should we make Tags a separate Node?

[axe312ger]

@itwasmattgregg I'd like to duplicate the pattern the Contentful GraphQL API implements this new feature.

To keep reviews doable, please keep in mind that this will be in a follow up PR

[pieh]

Published new alpha version - gatsby-source-contentful@9.0.0-alpha.3

[axe312ger]

Published new alpha version - gatsby-source-contentful@9.0.0-alpha.4

[axe312ger]

We published new alpha versions:

• gatsby-source-contentful@9.0.0-alpha.8
• gatsby@5.14.0-ctf-next.0

[bartveneman]

👋 Long time plugin user here, nice progress!

Just to add context on the necessity of getting this PR merged: I started a discussion on the potential workarounds I need to do to get a site working that has a restricted content model ID, where I'm confident that this PR could solve my problems in a better way than the alternatives I can think of. #38908