graphql.js

const graphql = require('graphql');

const _ = require('lodash');
const constants = require('../constants');

const {
    parse,
    validate,
    validateSchema,
    execute,
    specifiedRules
} = graphql;

const parseMemoized = _.memoize(source => {
    return parse(source);
});

module.exports = async (args = {}) => {
    let {
        schema,
        source
    } = args;

    // no need to validate schema each time in production, it is validated in tests
    if (!constants.config.production) {
        const schemaValidationErrors = validateSchema(schema);

        if (_.size(schemaValidationErrors)) {
            return {
                errors: schemaValidationErrors
            };
        }
    }

    const documentAST = parseMemoized(source);

    if (!constants.config.production) {
        // enable fields with same name and different types on union types
        const rules = _.filter(specifiedRules, rule => {
            return rule.name !== 'OverlappingFieldsCanBeMergedRule';
        });
    
        const errors = validate(
            schema,
            documentAST,
            rules
        );
    
        if (_.size(errors)) {
            return {
                errors
            };
        }
    }

    return await execute(
        schema,
        documentAST,
        args.rootValue || {},
        args.contextValue || {},
        args.variableValues || {},
        args.operationName || null
    );
};