Neo4j Helpers

createQueryExecutor.js

'use strict';

const CypherQuery = require('./cypher').CypherQuery;

module.exports = function createQueryExecutor(context) {
  const executor = function executeQuery(query) {
    if (typeof query === 'function') {
      return query(executor);
    }

    const rawQuery = query instanceof CypherQuery
      ? query.getRawQuery()
      : query;

    return new Promise((resolve, reject) => {
      context.cypher(rawQuery, (err, result) => {
        if (err) {
          reject(err);
        } else {
          resolve(result);
        }
      });
    });
  };

  return executor;
}

createTransactionExecutor.js

'use strict';

const createQueryExecutor = require('./createQueryExecutor');

module.exports = function createTransactionExecutor(db) {
  return function executeTransaction(cb) {
    const tx = db.beginTransaction();

    const executeQuery = createQueryExecutor(tx);

    return Promise.resolve(executeQuery(cb))
      .then((result) => {
        return new Promise((resolve, reject) => {
          tx.commit((err) => {
            if (err) {
              reject(err);
            } else {
              resolve(result);
            }
          });
        });
      })
      .then(undefined, (err) => {
        if (tx.state === tx.STATE_OPEN || tx.state === tx.STATE_PENDING) {
          return new Promise((resolve, reject) => {
            tx.rollback(() => {
              reject(err);
            });
          });
        }

        throw err;
      });
  };
};

cypher.js

'use strict';

class CypherQuery {
  constructor(strings, values) {
    this._strings = strings;
    this._values = values;
  }

  getRawQuery() {
    return this._getRawQuery({paramPrefix: 'p_'});
  }

  _getRawQuery(config) {
    const paramPrefix = config.paramPrefix;

    return this._strings
      .reduce((rawQuery, string, index) => {
        const query = rawQuery.query;
        const params = rawQuery.params;

        if (index === 0) {
          return {query: string, params: {}};
        }

        const paramIndex = index - 1;
        const value = this._values[paramIndex];

        if (value instanceof CypherQuery) {
          const options = value._getRawQuery({
            paramPrefix: paramPrefix + paramIndex + '_',
          });

          return {
            query: `${query}${options.query}${string}`,
            params: Object.assign({}, params, options.params),
          };
        }

        return {
          query: `${query}{${paramPrefix}${paramIndex}}${string}`,
          params: Object.assign({}, params, {
            [`${paramPrefix}${paramIndex}`]: value,
          }),
        };
      }, {query: '', params: {}});
  }
}

function cypher(strings) {
  const values = Array.prototype.slice.call(arguments, 1);

  return new CypherQuery(strings, values);
}

module.exports.CypherQuery = CypherQuery;
module.exports.cypher = cypher;

@vslinko Hi - I was looking through your Ripster repo and must say well done. I use neo4j a lot and recently discovered React/Redux, Graphql and Relay.

I'm particularly interested right now in moving an existing Neo4j + Rails api to Neo4j + Node + Graphql. Could you I ask you a for a big favour - to comment the above 3 gist which i see is also featured in the ripster: src/graphql/db.js file.

I can follow most of the code but a little lost here - the bit I'm not following so well is in the _getRawQuery method in the cypher.js above.

@Pepeye I'm on a similar learning path myself, haven't tried this code yet, but looking forward to it. Would be great to collaborate on learning resources! Have you seen this one yet: https://github.com/chentsulin/awesome-graphql ? It seems there's not too many GraphQL + Neo4j resources out there yet...