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import { inspect } from '../../jsutils/inspect.mjs';
import { GraphQLError } from '../../error/GraphQLError.mjs';
import { Kind } from '../../language/kinds.mjs';
import { print } from '../../language/printer.mjs';
import {
getNamedType,
isInterfaceType,
isLeafType,
isListType,
isNonNullType,
isObjectType,
} from '../../type/definition.mjs';
import { sortValueNode } from '../../utilities/sortValueNode.mjs';
import { typeFromAST } from '../../utilities/typeFromAST.mjs';
function reasonMessage(reason) {
if (Array.isArray(reason)) {
return reason
.map(
([responseName, subReason]) =>
`subfields "${responseName}" conflict because ` +
reasonMessage(subReason),
)
.join(' and ');
}
return reason;
}
/**
* Overlapping fields can be merged
*
* A selection set is only valid if all fields (including spreading any
* fragments) either correspond to distinct response names or can be merged
* without ambiguity.
*
* See https://spec.graphql.org/draft/#sec-Field-Selection-Merging
*/
export function OverlappingFieldsCanBeMergedRule(context) {
// A memoization for when two fragments are compared "between" each other for
// conflicts. Two fragments may be compared many times, so memoizing this can
// dramatically improve the performance of this validator.
const comparedFragmentPairs = new PairSet(); // A cache for the "field map" and list of fragment names found in any given
// selection set. Selection sets may be asked for this information multiple
// times, so this improves the performance of this validator.
const cachedFieldsAndFragmentNames = new Map();
return {
SelectionSet(selectionSet) {
const conflicts = findConflictsWithinSelectionSet(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
context.getParentType(),
selectionSet,
);
for (const [[responseName, reason], fields1, fields2] of conflicts) {
const reasonMsg = reasonMessage(reason);
context.reportError(
new GraphQLError(
`Fields "${responseName}" conflict because ${reasonMsg}. Use different aliases on the fields to fetch both if this was intentional.`,
{
nodes: fields1.concat(fields2),
},
),
);
}
},
};
}
/**
* Algorithm:
*
* Conflicts occur when two fields exist in a query which will produce the same
* response name, but represent differing values, thus creating a conflict.
* The algorithm below finds all conflicts via making a series of comparisons
* between fields. In order to compare as few fields as possible, this makes
* a series of comparisons "within" sets of fields and "between" sets of fields.
*
* Given any selection set, a collection produces both a set of fields by
* also including all inline fragments, as well as a list of fragments
* referenced by fragment spreads.
*
* A) Each selection set represented in the document first compares "within" its
* collected set of fields, finding any conflicts between every pair of
* overlapping fields.
* Note: This is the *only time* that a the fields "within" a set are compared
* to each other. After this only fields "between" sets are compared.
*
* B) Also, if any fragment is referenced in a selection set, then a
* comparison is made "between" the original set of fields and the
* referenced fragment.
*
* C) Also, if multiple fragments are referenced, then comparisons
* are made "between" each referenced fragment.
*
* D) When comparing "between" a set of fields and a referenced fragment, first
* a comparison is made between each field in the original set of fields and
* each field in the the referenced set of fields.
*
* E) Also, if any fragment is referenced in the referenced selection set,
* then a comparison is made "between" the original set of fields and the
* referenced fragment (recursively referring to step D).
*
* F) When comparing "between" two fragments, first a comparison is made between
* each field in the first referenced set of fields and each field in the the
* second referenced set of fields.
*
* G) Also, any fragments referenced by the first must be compared to the
* second, and any fragments referenced by the second must be compared to the
* first (recursively referring to step F).
*
* H) When comparing two fields, if both have selection sets, then a comparison
* is made "between" both selection sets, first comparing the set of fields in
* the first selection set with the set of fields in the second.
*
* I) Also, if any fragment is referenced in either selection set, then a
* comparison is made "between" the other set of fields and the
* referenced fragment.
*
* J) Also, if two fragments are referenced in both selection sets, then a
* comparison is made "between" the two fragments.
*
*/
// Find all conflicts found "within" a selection set, including those found
// via spreading in fragments. Called when visiting each SelectionSet in the
// GraphQL Document.
function findConflictsWithinSelectionSet(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
parentType,
selectionSet,
) {
const conflicts = [];
const [fieldMap, fragmentNames] = getFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
parentType,
selectionSet,
); // (A) Find find all conflicts "within" the fields of this selection set.
// Note: this is the *only place* `collectConflictsWithin` is called.
collectConflictsWithin(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
fieldMap,
);
if (fragmentNames.length !== 0) {
// (B) Then collect conflicts between these fields and those represented by
// each spread fragment name found.
for (let i = 0; i < fragmentNames.length; i++) {
collectConflictsBetweenFieldsAndFragment(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
false,
fieldMap,
fragmentNames[i],
); // (C) Then compare this fragment with all other fragments found in this
// selection set to collect conflicts between fragments spread together.
// This compares each item in the list of fragment names to every other
// item in that same list (except for itself).
for (let j = i + 1; j < fragmentNames.length; j++) {
collectConflictsBetweenFragments(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
false,
fragmentNames[i],
fragmentNames[j],
);
}
}
}
return conflicts;
} // Collect all conflicts found between a set of fields and a fragment reference
// including via spreading in any nested fragments.
function collectConflictsBetweenFieldsAndFragment(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap,
fragmentName,
) {
const fragment = context.getFragment(fragmentName);
if (!fragment) {
return;
}
const [fieldMap2, referencedFragmentNames] =
getReferencedFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
fragment,
); // Do not compare a fragment's fieldMap to itself.
if (fieldMap === fieldMap2) {
return;
} // (D) First collect any conflicts between the provided collection of fields
// and the collection of fields represented by the given fragment.
collectConflictsBetween(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap,
fieldMap2,
); // (E) Then collect any conflicts between the provided collection of fields
// and any fragment names found in the given fragment.
for (const referencedFragmentName of referencedFragmentNames) {
// Memoize so two fragments are not compared for conflicts more than once.
if (
comparedFragmentPairs.has(
referencedFragmentName,
fragmentName,
areMutuallyExclusive,
)
) {
continue;
}
comparedFragmentPairs.add(
referencedFragmentName,
fragmentName,
areMutuallyExclusive,
);
collectConflictsBetweenFieldsAndFragment(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap,
referencedFragmentName,
);
}
} // Collect all conflicts found between two fragments, including via spreading in
// any nested fragments.
function collectConflictsBetweenFragments(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fragmentName1,
fragmentName2,
) {
// No need to compare a fragment to itself.
if (fragmentName1 === fragmentName2) {
return;
} // Memoize so two fragments are not compared for conflicts more than once.
if (
comparedFragmentPairs.has(
fragmentName1,
fragmentName2,
areMutuallyExclusive,
)
) {
return;
}
comparedFragmentPairs.add(fragmentName1, fragmentName2, areMutuallyExclusive);
const fragment1 = context.getFragment(fragmentName1);
const fragment2 = context.getFragment(fragmentName2);
if (!fragment1 || !fragment2) {
return;
}
const [fieldMap1, referencedFragmentNames1] =
getReferencedFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
fragment1,
);
const [fieldMap2, referencedFragmentNames2] =
getReferencedFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
fragment2,
); // (F) First, collect all conflicts between these two collections of fields
// (not including any nested fragments).
collectConflictsBetween(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap1,
fieldMap2,
); // (G) Then collect conflicts between the first fragment and any nested
// fragments spread in the second fragment.
for (const referencedFragmentName2 of referencedFragmentNames2) {
collectConflictsBetweenFragments(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fragmentName1,
referencedFragmentName2,
);
} // (G) Then collect conflicts between the second fragment and any nested
// fragments spread in the first fragment.
for (const referencedFragmentName1 of referencedFragmentNames1) {
collectConflictsBetweenFragments(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
referencedFragmentName1,
fragmentName2,
);
}
} // Find all conflicts found between two selection sets, including those found
// via spreading in fragments. Called when determining if conflicts exist
// between the sub-fields of two overlapping fields.
function findConflictsBetweenSubSelectionSets(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
parentType1,
selectionSet1,
parentType2,
selectionSet2,
) {
const conflicts = [];
const [fieldMap1, fragmentNames1] = getFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
parentType1,
selectionSet1,
);
const [fieldMap2, fragmentNames2] = getFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
parentType2,
selectionSet2,
); // (H) First, collect all conflicts between these two collections of field.
collectConflictsBetween(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap1,
fieldMap2,
); // (I) Then collect conflicts between the first collection of fields and
// those referenced by each fragment name associated with the second.
for (const fragmentName2 of fragmentNames2) {
collectConflictsBetweenFieldsAndFragment(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap1,
fragmentName2,
);
} // (I) Then collect conflicts between the second collection of fields and
// those referenced by each fragment name associated with the first.
for (const fragmentName1 of fragmentNames1) {
collectConflictsBetweenFieldsAndFragment(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fieldMap2,
fragmentName1,
);
} // (J) Also collect conflicts between any fragment names by the first and
// fragment names by the second. This compares each item in the first set of
// names to each item in the second set of names.
for (const fragmentName1 of fragmentNames1) {
for (const fragmentName2 of fragmentNames2) {
collectConflictsBetweenFragments(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
fragmentName1,
fragmentName2,
);
}
}
return conflicts;
} // Collect all Conflicts "within" one collection of fields.
function collectConflictsWithin(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
fieldMap,
) {
// A field map is a keyed collection, where each key represents a response
// name and the value at that key is a list of all fields which provide that
// response name. For every response name, if there are multiple fields, they
// must be compared to find a potential conflict.
for (const [responseName, fields] of Object.entries(fieldMap)) {
// This compares every field in the list to every other field in this list
// (except to itself). If the list only has one item, nothing needs to
// be compared.
if (fields.length > 1) {
for (let i = 0; i < fields.length; i++) {
for (let j = i + 1; j < fields.length; j++) {
const conflict = findConflict(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
false, // within one collection is never mutually exclusive
responseName,
fields[i],
fields[j],
);
if (conflict) {
conflicts.push(conflict);
}
}
}
}
}
} // Collect all Conflicts between two collections of fields. This is similar to,
// but different from the `collectConflictsWithin` function above. This check
// assumes that `collectConflictsWithin` has already been called on each
// provided collection of fields. This is true because this validator traverses
// each individual selection set.
function collectConflictsBetween(
context,
conflicts,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
parentFieldsAreMutuallyExclusive,
fieldMap1,
fieldMap2,
) {
// A field map is a keyed collection, where each key represents a response
// name and the value at that key is a list of all fields which provide that
// response name. For any response name which appears in both provided field
// maps, each field from the first field map must be compared to every field
// in the second field map to find potential conflicts.
for (const [responseName, fields1] of Object.entries(fieldMap1)) {
const fields2 = fieldMap2[responseName];
if (fields2) {
for (const field1 of fields1) {
for (const field2 of fields2) {
const conflict = findConflict(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
parentFieldsAreMutuallyExclusive,
responseName,
field1,
field2,
);
if (conflict) {
conflicts.push(conflict);
}
}
}
}
}
} // Determines if there is a conflict between two particular fields, including
// comparing their sub-fields.
function findConflict(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
parentFieldsAreMutuallyExclusive,
responseName,
field1,
field2,
) {
const [parentType1, node1, def1] = field1;
const [parentType2, node2, def2] = field2; // If it is known that two fields could not possibly apply at the same
// time, due to the parent types, then it is safe to permit them to diverge
// in aliased field or arguments used as they will not present any ambiguity
// by differing.
// It is known that two parent types could never overlap if they are
// different Object types. Interface or Union types might overlap - if not
// in the current state of the schema, then perhaps in some future version,
// thus may not safely diverge.
const areMutuallyExclusive =
parentFieldsAreMutuallyExclusive ||
(parentType1 !== parentType2 &&
isObjectType(parentType1) &&
isObjectType(parentType2));
if (!areMutuallyExclusive) {
// Two aliases must refer to the same field.
const name1 = node1.name.value;
const name2 = node2.name.value;
if (name1 !== name2) {
return [
[responseName, `"${name1}" and "${name2}" are different fields`],
[node1],
[node2],
];
} // Two field calls must have the same arguments.
if (!sameArguments(node1, node2)) {
return [
[responseName, 'they have differing arguments'],
[node1],
[node2],
];
}
} // The return type for each field.
const type1 = def1 === null || def1 === void 0 ? void 0 : def1.type;
const type2 = def2 === null || def2 === void 0 ? void 0 : def2.type;
if (type1 && type2 && doTypesConflict(type1, type2)) {
return [
[
responseName,
`they return conflicting types "${inspect(type1)}" and "${inspect(
type2,
)}"`,
],
[node1],
[node2],
];
} // Collect and compare sub-fields. Use the same "visited fragment names" list
// for both collections so fields in a fragment reference are never
// compared to themselves.
const selectionSet1 = node1.selectionSet;
const selectionSet2 = node2.selectionSet;
if (selectionSet1 && selectionSet2) {
const conflicts = findConflictsBetweenSubSelectionSets(
context,
cachedFieldsAndFragmentNames,
comparedFragmentPairs,
areMutuallyExclusive,
getNamedType(type1),
selectionSet1,
getNamedType(type2),
selectionSet2,
);
return subfieldConflicts(conflicts, responseName, node1, node2);
}
}
function sameArguments(node1, node2) {
const args1 = node1.arguments;
const args2 = node2.arguments;
if (args1 === undefined || args1.length === 0) {
return args2 === undefined || args2.length === 0;
}
if (args2 === undefined || args2.length === 0) {
return false;
}
/* c8 ignore next */
if (args1.length !== args2.length) {
/* c8 ignore next */
return false;
/* c8 ignore next */
}
const values2 = new Map(args2.map(({ name, value }) => [name.value, value]));
return args1.every((arg1) => {
const value1 = arg1.value;
const value2 = values2.get(arg1.name.value);
if (value2 === undefined) {
return false;
}
return stringifyValue(value1) === stringifyValue(value2);
});
}
function stringifyValue(value) {
return print(sortValueNode(value));
} // Two types conflict if both types could not apply to a value simultaneously.
// Composite types are ignored as their individual field types will be compared
// later recursively. However List and Non-Null types must match.
function doTypesConflict(type1, type2) {
if (isListType(type1)) {
return isListType(type2)
? doTypesConflict(type1.ofType, type2.ofType)
: true;
}
if (isListType(type2)) {
return true;
}
if (isNonNullType(type1)) {
return isNonNullType(type2)
? doTypesConflict(type1.ofType, type2.ofType)
: true;
}
if (isNonNullType(type2)) {
return true;
}
if (isLeafType(type1) || isLeafType(type2)) {
return type1 !== type2;
}
return false;
} // Given a selection set, return the collection of fields (a mapping of response
// name to field nodes and definitions) as well as a list of fragment names
// referenced via fragment spreads.
function getFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
parentType,
selectionSet,
) {
const cached = cachedFieldsAndFragmentNames.get(selectionSet);
if (cached) {
return cached;
}
const nodeAndDefs = Object.create(null);
const fragmentNames = Object.create(null);
_collectFieldsAndFragmentNames(
context,
parentType,
selectionSet,
nodeAndDefs,
fragmentNames,
);
const result = [nodeAndDefs, Object.keys(fragmentNames)];
cachedFieldsAndFragmentNames.set(selectionSet, result);
return result;
} // Given a reference to a fragment, return the represented collection of fields
// as well as a list of nested fragment names referenced via fragment spreads.
function getReferencedFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
fragment,
) {
// Short-circuit building a type from the node if possible.
const cached = cachedFieldsAndFragmentNames.get(fragment.selectionSet);
if (cached) {
return cached;
}
const fragmentType = typeFromAST(context.getSchema(), fragment.typeCondition);
return getFieldsAndFragmentNames(
context,
cachedFieldsAndFragmentNames,
fragmentType,
fragment.selectionSet,
);
}
function _collectFieldsAndFragmentNames(
context,
parentType,
selectionSet,
nodeAndDefs,
fragmentNames,
) {
for (const selection of selectionSet.selections) {
switch (selection.kind) {
case Kind.FIELD: {
const fieldName = selection.name.value;
let fieldDef;
if (isObjectType(parentType) || isInterfaceType(parentType)) {
fieldDef = parentType.getFields()[fieldName];
}
const responseName = selection.alias
? selection.alias.value
: fieldName;
if (!nodeAndDefs[responseName]) {
nodeAndDefs[responseName] = [];
}
nodeAndDefs[responseName].push([parentType, selection, fieldDef]);
break;
}
case Kind.FRAGMENT_SPREAD:
fragmentNames[selection.name.value] = true;
break;
case Kind.INLINE_FRAGMENT: {
const typeCondition = selection.typeCondition;
const inlineFragmentType = typeCondition
? typeFromAST(context.getSchema(), typeCondition)
: parentType;
_collectFieldsAndFragmentNames(
context,
inlineFragmentType,
selection.selectionSet,
nodeAndDefs,
fragmentNames,
);
break;
}
}
}
} // Given a series of Conflicts which occurred between two sub-fields, generate
// a single Conflict.
function subfieldConflicts(conflicts, responseName, node1, node2) {
if (conflicts.length > 0) {
return [
[responseName, conflicts.map(([reason]) => reason)],
[node1, ...conflicts.map(([, fields1]) => fields1).flat()],
[node2, ...conflicts.map(([, , fields2]) => fields2).flat()],
];
}
}
/**
* A way to keep track of pairs of things when the ordering of the pair does not matter.
*/
class PairSet {
constructor() {
this._data = new Map();
}
has(a, b, areMutuallyExclusive) {
var _this$_data$get;
const [key1, key2] = a < b ? [a, b] : [b, a];
const result =
(_this$_data$get = this._data.get(key1)) === null ||
_this$_data$get === void 0
? void 0
: _this$_data$get.get(key2);
if (result === undefined) {
return false;
} // areMutuallyExclusive being false is a superset of being true, hence if
// we want to know if this PairSet "has" these two with no exclusivity,
// we have to ensure it was added as such.
return areMutuallyExclusive ? true : areMutuallyExclusive === result;
}
add(a, b, areMutuallyExclusive) {
const [key1, key2] = a < b ? [a, b] : [b, a];
const map = this._data.get(key1);
if (map === undefined) {
this._data.set(key1, new Map([[key2, areMutuallyExclusive]]));
} else {
map.set(key2, areMutuallyExclusive);
}
}
}