Do not require fragments to have `id` in their root in `require-id-when-available`

Fragments should not be required to include id field on their root selection set, as this is the query’s responsibility.

This causes a couple of issues:

• Fragments have to include id which they may not need at all
• If multiple fragments are inlined, all of them need to include the id
• If id is missing on the query and all used fragments, errors are reported for the query and all fragments, making the problem much worse than it is

Consider this example:

fragment UserAvatar {
  firstName
  lastName
  avatar
}
fragment UserManager {
  manager {
    id
    ...UserAvatar
  }
}

query GetCurrentUser {
  me {
    id
    ...UserAvatar
    ...UserManager
  }
}

Both fragments define data requirements of simple UI components - they don’t need the User’s id to work at all. This should be added on the query level, as this is the cache’s requirement.

An exception to this is when deeper objects are queried in fragments. Queries don’t know about the fragment internals, so in this case, it’s fragment’s responsiblity to query the id.

I’ve made a working change on my fork as we’re using this in a big project: https://github.com/dotansimha/graphql-eslint/compare/master...panrafal:panrafal/dont-require-id-on-fragment-root

[B2o5T]

Hi @panrafal, thanks for the report, this will be tricky to implement, but I’ll work on this to make graphql-eslint better 🥳

[dotansimha]

Hey @panrafal the tricky part is that we can make this rule smarter without ignoring id field for fragments by checking if the fragment is imported by some operation and at least 1 operation requires his id field.

@dotansimha what do you think?

Agree, I think we can consider adding support for parserServices - to allow us to check if a fragment is used and get a list of operations that are using it and then validate it there. It might add some complexity because fragments might be used by other fragments that are used in a query - so this needs some way to “flatten” the query that uses each fragment, and then check if the id is used there?