79 lines
2.3 KiB
JavaScript
79 lines
2.3 KiB
JavaScript
import { GraphQLError } from '../../error/GraphQLError.mjs';
|
|
|
|
/**
|
|
* No fragment cycles
|
|
*
|
|
* The graph of fragment spreads must not form any cycles including spreading itself.
|
|
* Otherwise an operation could infinitely spread or infinitely execute on cycles in the underlying data.
|
|
*
|
|
* See https://spec.graphql.org/draft/#sec-Fragment-spreads-must-not-form-cycles
|
|
*/
|
|
export function NoFragmentCyclesRule(context) {
|
|
// Tracks already visited fragments to maintain O(N) and to ensure that cycles
|
|
// are not redundantly reported.
|
|
const visitedFrags = Object.create(null); // Array of AST nodes used to produce meaningful errors
|
|
|
|
const spreadPath = []; // Position in the spread path
|
|
|
|
const spreadPathIndexByName = Object.create(null);
|
|
return {
|
|
OperationDefinition: () => false,
|
|
|
|
FragmentDefinition(node) {
|
|
detectCycleRecursive(node);
|
|
return false;
|
|
},
|
|
}; // This does a straight-forward DFS to find cycles.
|
|
// It does not terminate when a cycle was found but continues to explore
|
|
// the graph to find all possible cycles.
|
|
|
|
function detectCycleRecursive(fragment) {
|
|
if (visitedFrags[fragment.name.value]) {
|
|
return;
|
|
}
|
|
|
|
const fragmentName = fragment.name.value;
|
|
visitedFrags[fragmentName] = true;
|
|
const spreadNodes = context.getFragmentSpreads(fragment.selectionSet);
|
|
|
|
if (spreadNodes.length === 0) {
|
|
return;
|
|
}
|
|
|
|
spreadPathIndexByName[fragmentName] = spreadPath.length;
|
|
|
|
for (const spreadNode of spreadNodes) {
|
|
const spreadName = spreadNode.name.value;
|
|
const cycleIndex = spreadPathIndexByName[spreadName];
|
|
spreadPath.push(spreadNode);
|
|
|
|
if (cycleIndex === undefined) {
|
|
const spreadFragment = context.getFragment(spreadName);
|
|
|
|
if (spreadFragment) {
|
|
detectCycleRecursive(spreadFragment);
|
|
}
|
|
} else {
|
|
const cyclePath = spreadPath.slice(cycleIndex);
|
|
const viaPath = cyclePath
|
|
.slice(0, -1)
|
|
.map((s) => '"' + s.name.value + '"')
|
|
.join(', ');
|
|
context.reportError(
|
|
new GraphQLError(
|
|
`Cannot spread fragment "${spreadName}" within itself` +
|
|
(viaPath !== '' ? ` via ${viaPath}.` : '.'),
|
|
{
|
|
nodes: cyclePath,
|
|
},
|
|
),
|
|
);
|
|
}
|
|
|
|
spreadPath.pop();
|
|
}
|
|
|
|
spreadPathIndexByName[fragmentName] = undefined;
|
|
}
|
|
}
|