index.js

'use strict'

const Redshift = require('node-redshift')
const path = require('path')
const fs = require('fs')
const vm = require('vm')

/**
 * Class for querying Redshift easily
 */

class RedshiftQuery {

  /**
   * Initializes a RedshiftQuery class
   * @param  {Object} opts   Configuration for the class
   */

  constructor(opts) {
    this.queryPath = opts.queryPath
    this.redshift = new Redshift(opts.connection)
  }

  /**
   * Queries a Redshift instance from the given file and parameters
   * @param  {String} sqlFile   Name of the file containing the query
   * @param  {Object} params    Object that contains parameters
   * @return {Array[Row]}       Array of results (underlying library is pg so the format will be the same)
   */

  queryByFile(sqlFile, params) {
    // Create a fully-qualified path to the desired file
    const sqlPath = path.resolve(this.queryPath, sqlFile)

    // Read from the file and cast it to a string
    let query = fs.readFileSync(sqlPath).toString()

    // Make the query a template string and eval it with
    // the given parameters.
    query = vm.runInNewContext('`' + query + '`', params)

    return this.queryByString(query)
  }

  /**
   * Queries a Redshift instance from the given query string
   * @param  {String} query    Redshift query
   * @return {Array[Row]}      Array of results (underlying library is pg so the format will be the same)
   */

  queryByString(query) {
    return new Promise((resolve, reject) => {
      // Execute the query and resolve the promise accordingly
      this.redshift.query(query, (err, data) => {
        if (err) {
          return reject(err)
        }

        return resolve(data)
      })
    })
  }
}

module.exports = RedshiftQuery