docparse-dumpinvoices/processStream.js

takes a list of couchdb invoice ids and exports the data contained within those invoices to an Excel spreadsheet

/**
 * Takes a stream of invoice objects and writes them to the excel spreadsheet
 */
var moment = require('moment');
var mime = require('mime');
var Stream = require('stream').Stream;
var spawn = require('child_process').spawn;
var inspect = require('eyespect').inspector();
var path = require('path');
var getTemplatePath = require('./getTemplatePath');
module.exports = function(feed, res, cb) {
  var filename = 'output-'+moment().format('YYYY MM DD hh-mm-ss')+'.xls';
  var mimetype = mime.lookup('.xls');
  if (res.setHeader) {
    res.setHeader('Content-disposition', 'attachment; filename=' + filename);
    res.setHeader('Content-type', mimetype);
  }
  var message;
  var template_path = getTemplatePath();
  var script_path = path.join(__dirname,'process.py');
  // feed.on('change', function (doc) {
  //   inspect(doc, 'got doc')
  // })

  var child = spawn('python', [script_path, template_path]);
  var format = new ArrayFormatter;
  var formatted = feed.pipe(format)
  formatted.pipe(child.stdin);
  child.stdout.pipe(res);
  // nothing should write to stderr
  child.stderr.setEncoding('utf8')

  var stdErr = ''
  child.stderr.on('data', function(data) {
    console.log(data)
    stdErr += data
    if (/^execvp\(\)/.test(data)) {
      inspect('Failed to start child process.', data);
    }
  })
  // prompt the user to download the spreadsheet
  var now = moment();
  child.on('close', function() {
    if (stdErr) {
      return cb({
        message: 'error dumping invoices to spreadsheet',
        error: stdErr,
        stack: new Error().stack
      })
    }
    now = null
    child = null
    template_path = null
    script_path = null
    mimetype = null
    res.end();
    res = null
    formatted = null
    format = null
    return cb();
  });
};


function ArrayFormatter () {
  Stream.call(this);
  this.writable = true;
  this._done = false;
}

ArrayFormatter.prototype.__proto__ = Stream.prototype;

ArrayFormatter.prototype.write = function (doc) {
  var text = JSON.stringify(doc).replace(/\\n/g,'');
  var output = text + '\n'
  this.emit('data', output)
  return true;
};

ArrayFormatter.prototype.end =
  ArrayFormatter.prototype.destroy = function () {
    if (this._done) return;
    this._done = true;
    // emit the end event to close the python process
    this.emit('end');
  };