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|
// @flow strict
import inspect from '../../jsutils/inspect';
import { GraphQLError } from '../../error/GraphQLError';
import type { ASTVisitor } from '../../language/visitor';
import type { GraphQLCompositeType } from '../../type/definition';
import { isCompositeType } from '../../type/definition';
import { typeFromAST } from '../../utilities/typeFromAST';
import { doTypesOverlap } from '../../utilities/typeComparators';
import type { ValidationContext } from '../ValidationContext';
/**
* Possible fragment spread
*
* A fragment spread is only valid if the type condition could ever possibly
* be true: if there is a non-empty intersection of the possible parent types,
* and possible types which pass the type condition.
*/
export function PossibleFragmentSpreadsRule(
context: ValidationContext,
): ASTVisitor {
return {
InlineFragment(node) {
const fragType = context.getType();
const parentType = context.getParentType();
if (
isCompositeType(fragType) &&
isCompositeType(parentType) &&
!doTypesOverlap(context.getSchema(), fragType, parentType)
) {
const parentTypeStr = inspect(parentType);
const fragTypeStr = inspect(fragType);
context.reportError(
new GraphQLError(
`Fragment cannot be spread here as objects of type "${parentTypeStr}" can never be of type "${fragTypeStr}".`,
node,
),
);
}
},
FragmentSpread(node) {
const fragName = node.name.value;
const fragType = getFragmentType(context, fragName);
const parentType = context.getParentType();
if (
fragType &&
parentType &&
!doTypesOverlap(context.getSchema(), fragType, parentType)
) {
const parentTypeStr = inspect(parentType);
const fragTypeStr = inspect(fragType);
context.reportError(
new GraphQLError(
`Fragment "${fragName}" cannot be spread here as objects of type "${parentTypeStr}" can never be of type "${fragTypeStr}".`,
node,
),
);
}
},
};
}
function getFragmentType(
context: ValidationContext,
name: string,
): ?GraphQLCompositeType {
const frag = context.getFragment(name);
if (frag) {
const type = typeFromAST(context.getSchema(), frag.typeCondition);
if (isCompositeType(type)) {
return type;
}
}
}
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