Function checkDepth

packages/query/src/graphql/plugins/QueryDepthLimitPlugin.ts:50–85

(
  node: ASTNode,
  fragments: Record<string, FragmentDefinitionNode>,
  depthSoFar: number,
  maxDepth: number
)

}

export function checkDepth(
  node: ASTNode,
  fragments: Record<string, FragmentDefinitionNode>,
  depthSoFar: number,
  maxDepth: number
): void {
  if (depthSoFar > maxDepth) {
    throw new GraphQLError(`Query is too deep. Maximum depth allowed is ${maxDepth}.`, [node]);
  }
  switch (node.kind) {
    case Kind.FIELD: {
      if (!node.selectionSet) {
        return;
      }

      node.selectionSet.selections.forEach((selection: SelectionNode) => {
        checkDepth(selection, fragments, depthSoFar + 1, maxDepth);
      });

      return;
    }
    case Kind.FRAGMENT_SPREAD: {
      return checkDepth(fragments[node.name.value], fragments, depthSoFar, maxDepth);
    }
    case Kind.INLINE_FRAGMENT:
    case Kind.FRAGMENT_DEFINITION:
    case Kind.OPERATION_DEFINITION: {
      node.selectionSet.selections.forEach((selection: SelectionNode) => {
        checkDepth(selection, fragments, depthSoFar, maxDepth);
      });
      return;
    }
    default:
      break;
  }
}

export function queryDepthLimitPlugin(options: {schema: GraphQLSchema; maxDepth?: number}): ApolloServerPlugin {
  return {