New Rule: Report Non-Null fields in root schema

[nishtahir]

I'd like to suggest a rule that reports non-null fields in the root schema in order to require partial responses.

Fail

Query {
    foo: Foo!
         ^^^^ Root query fields are required to be non-null
}

Pass

Query {
    foo: Foo
}

[nishtahir]

I've put together an implementation of this here master...nishtahir:graphql-eslint:master. If there's interest in the rule, I can open a PR with it.

[dimaMachina]

Hi! Can you attach more details on why you want it? Maybe some pattern or spec that you follow

[nishtahir]

@B2o5T This is to allow for partial responses queries that access multiple root fields. Also referenced here. A prerequisite for this is that the type of the root field is nullable. Non-null fields cause the entire query to fail if the resolver cannot complete it because null is not an acceptable return value.

For example,

type Query {
    foo: Foo!, 
    bar: Bar!
}

with a query of

query {
   foo: { ... },
   bar: { ... }
}

Would return nothing if foo or bar could not complete. Where a partial response would be acceptable.

data : {
    foo: null,
    bar: { ... },
    errors: [ foo: "foo error" ]
}

[dimaMachina]

Accepted, you can send a PR

[nishtahir]

Thanks for putting the release together but looks like there might have been an issue there. I'm running into this error

Oops! Something went wrong! :(

ESLint: 8.36.0

TypeError: Cannot read properties of undefined (reading 'kind')
Occurred while linting file.graphql:8
Rule: "@graphql-eslint/require-nullable-result-in-root"
    at getNodeName (node_modules/@graphql-eslint/eslint-plugin/cjs/utils.js:128:18)
    at ObjectTypeDefinition,ObjectTypeExtension (node_modules/@graphql-eslint/eslint-plugin/cjs/rules/require-nullable-result-in-root.js:59:76)
    at ruleErrorHandler (node_modules/eslint/lib/linter/linter.js:1118:28)
    at node_modules/eslint/lib/linter/safe-emitter.js:45:58
    at Array.forEach (<anonymous>)
    at Object.emit (node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (node_modules/eslint/lib/linter/node-event-generator.js:297:26)
    at NodeEventGenerator.applySelectors (node_modules/eslint/lib/linter/node-event-generator.js:326:22)
    at NodeEventGenerator.enterNode (node_modules/eslint/lib/linter/node-event-generator.js:340:14)
    at CodePathAnalyzer.enterNode (node_modules/eslint/lib/linter/code-path-analysis/code-path-analyzer.js:795:23)

After digging into the issue looks like the bug is here
https://github.com/B2o5T/graphql-eslint/blob/baf0c46deb710eabab2262da5d9faa94eb2650b8/packages/plugin/src/rules/require-nullable-result-in-root.ts#L66

As far as I can tell this affects built-in scalar types

GraphQLScalarType {
  name: 'Boolean',
  description: 'The `Boolean` scalar type represents `true` or `false`.',
  specifiedByURL: undefined,
  serialize: [Function: serialize],
  parseValue: [Function: parseValue],
  parseLiteral: [Function: parseLiteral],
  extensions: [Object: null prototype] {},
  astNode: undefined,
  extensionASTNodes: []
}

I think the fix here might be to update the line to

          const resultType = (type && type.astNode) ? getNodeName(type.astNode as any) : '';

and possibly use type.name for the reporter and fixer. @B2o5T do you have any thoughts?

[dimaMachina]

@nishtahir I’ll release a fix today, sorry

[nishtahir]

I'm also happy to put together a PR if you need the help

[dimaMachina]

@nishtahir fix is on the way 🤲

[mat813]

It would maybe be great that extend type Mutation and extend type Subscription be ignored as is extend type Query.