graphql/validation/rules/NoUndefinedVariables.js.flow

A Query Language and Runtime which can target any service.

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict
 */

import type { ValidationContext } from '../ValidationContext';
import { GraphQLError } from '../../error/GraphQLError';
import type { ASTVisitor } from '../../language/visitor';

export function undefinedVarMessage(varName: string, opName: ?string): string {
  return opName
    ? `Variable "$${varName}" is not defined by operation "${opName}".`
    : `Variable "$${varName}" is not defined.`;
}

/**
 * No undefined variables
 *
 * A GraphQL operation is only valid if all variables encountered, both directly
 * and via fragment spreads, are defined by that operation.
 */
export function NoUndefinedVariables(context: ValidationContext): ASTVisitor {
  let variableNameDefined = Object.create(null);

  return {
    OperationDefinition: {
      enter() {
        variableNameDefined = Object.create(null);
      },
      leave(operation) {
        const usages = context.getRecursiveVariableUsages(operation);

        for (const { node } of usages) {
          const varName = node.name.value;
          if (variableNameDefined[varName] !== true) {
            context.reportError(
              new GraphQLError(
                undefinedVarMessage(
                  varName,
                  operation.name && operation.name.value,
                ),
                [node, operation],
              ),
            );
          }
        }
      },
    },
    VariableDefinition(node) {
      variableNameDefined[node.variable.name.value] = true;
    },
  };
}