Not possible to mark parent as `@required` if parent is nullable due to child being a nullable fragment

[joleeee]

Describe the bug

TLDR; if a query has a fragment with a @required in a top level field, it bubbles up to the query, but it's not possible to mark the parent of the fragment spread @required.

Example:

I have a fragment

fragment AirportParts on airports @required {
    id
    location @required {
        city
    }
}

And i use it in a query

query MyQuery {
    flights {
        to {
            ...AirportParts @mask_disable
        }
    }
}

Naturally, it leads to a nullable to:

export type MyQuery$result = {
    /**
     * An array relationship
    */
    readonly flights: ({
        /**
         * An object relationship
        */
        readonly to: { // <----- to IS NULLABLE
            readonly id: number;
            readonly iata: string | null;
            /**
             * An object relationship
            */
            readonly location: {
                readonly city: string;
                readonly name: string;
            };
            readonly " $fragments": {
                AirportParts: {};
            };
        } | null; // <----- to IS NULLABLE
    })[];
};

However, it is not possible to mark the to as required:

If you try:

query MyQuery {
    flights {
-        to {
+        to @required {
            ...AirportParts @mask_disable
        }
    }
}

❌ Encountered error in src/routes/.../query.gql
@required may only be used on nullable fields

Reproduction

No response

[AlecAivazis]

Hm maybe i'm missing something subtle in your issue but you wouldn't need to mark to with @required if the field is non-null. since it would always have a value

[joleeee]

Thanks for replying

readonly to: { ... } | null; 

means it is typed as nullable

[joleeee]

Sorry, but the point was that the field is nullable so i want to add @required, but houdini mistakenly says it is not nullable @AlecAivazis

[joleeee]

Commenting out this check makes it work. So it seems there is different logic in checking if @required is valid, and actually applying it.

houdini/packages/houdini/src/codegen/validators/typeCheck.ts

Lines 409 to 416 in d7b30f0

	if (!isServerNullable && !isAlreadyClientNullable) {
	ctx.reportError(
	new graphql.GraphQLError(
	`@${config.requiredDirective} may only be used on nullable fields`
	)
	)
	return
	}

[SeppahBaws]

What is the type of that field in your graphql schema?

[joleeee]

I think I made a patch that makes it work? But I might've done something weird the the existing logic.

What is the type of that field in your graphql schema?

I'm new to graphql, how can I see this? I use hasura with a postgres backend if it is of any help...

[joleeee]

I removed the irrelevant fields

type flights {
  to: airports!
}

type airports {
  id: Int!
  location: locations
}

type locations {
  city: String!
}

[SeppahBaws]

the to field on flights is non-nullable, so that's why the @required directive cannot be used there.

[joleeee]

Yes but ... AirportParts has a @require, which bubbles up to to, which means to becomes nullable, as seen by the typescript output!

[AlecAivazis]

Just a heads up - this should be fixed in the upcoming go compiler. I hope to have something you can test against in a week or 2