forked from graphql/graphql-js
/
UniqueArgumentNamesRule.ts
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/
UniqueArgumentNamesRule.ts
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import { GraphQLError } from '../../error/GraphQLError';
import type { ASTVisitor } from '../../language/visitor';
import type { ASTValidationContext } from '../ValidationContext';
/**
* Unique argument names
*
* A GraphQL field or directive is only valid if all supplied arguments are
* uniquely named.
*
* See https://spec.graphql.org/draft/#sec-Argument-Names
*/
export function UniqueArgumentNamesRule(
context: ASTValidationContext,
): ASTVisitor {
let knownArgNames = Object.create(null);
return {
Field() {
knownArgNames = Object.create(null);
},
Directive() {
knownArgNames = Object.create(null);
},
Argument(node) {
const argName = node.name.value;
if (knownArgNames[argName]) {
context.reportError(
new GraphQLError(
`There can be only one argument named "${argName}".`,
[knownArgNames[argName], node.name],
),
);
} else {
knownArgNames[argName] = node.name;
}
return false;
},
};
}