Seeding Data for a StrongLoop App

please read! a few hours after posting this, a member of the strongloop team pointed out an alternative that did exactly what i wanted to accomplish in about one second of typing. i still think the core of this blog entry makes sense as is so i’m not editing it, but see the note at the bottom!

this is just a quick post as a followup to something i mentioned in my post the other day on building a blog with strongloop . i mentioned that while working on my application, i kept losing my temporary data as i was using the “in memory” datasource that is the default persistence method for data. that’s not a bug—in memory means exactly that—in memory—and as i restarted the app (using nodemon ), i had to re-enter fake data to test.

while it takes all of three minutes to connect your app to mongo, if you don’t have mongo (or mysql, or a db in general), it would be nice to be able to stick with the simple ram based system while prototyping.

one of the things i realized is that strongloop will run a set of scripts inside the boot directory on startup. in theory, that could be used to set some seed data. jordan kasper (evangelist for strongloop, which sounds like a fun job, ahem) shared this script with me as an example:

https://github.com/strongloop-training/coffee-time/blob/master/server/boot/create-sample-model-data.js

var async = require('async');
var mysqldatasourcename = 'mysql_dev';
var mongodatasourcename = 'mongodb_dev';

module.exports = function(app) {
  //data sources
  var mongods = app.datasources[mongodatasourcename];
  var mysqlds = app.datasources[mysqldatasourcename];
  //create all models
  async.parallel({
    reviewers: async.apply(createreviewers),
    coffeeshops: async.apply(createcoffeeshops),
  }, function(err, results) {
    if (err) throw err;
    createreviews(results.reviewers, results.coffeeshops, function(err) {
      if (err) throw err;
      console.log('> models created sucessfully');
    });
  });
  //create reviewers
  function createreviewers(cb) {
    mongods.automigrate('reviewer', function(err) {
      if (err) return cb(err);
      var reviewer = app.models.reviewer;
      reviewer.create([
        {email: 'foo@bar.com', password: 'foobar'},
        {email: 'john@doe.com', password: 'johndoe'},
        {email: 'jane@doe.com', password: 'janedoe'}
      ], cb);
    });
  }
  //create coffee shops
  function createcoffeeshops(cb) {
    mysqlds.automigrate('coffeeshop', function(err) {
      if (err) return cb(err);
      var coffeeshop = app.models.coffeeshop;
      var shops = [
        {name: 'bel cafe',openinghour:10, closinghour:18},
        {name: 'three bees coffee house',openinghour:6, closinghour:15},
        {name: 'caffe artigiano',openinghour:17, closinghour:24},
      ];
      //add city if it's in the model
      if(coffeeshop.definition.properties.hasownproperty('city')){
        var cities = ['vancouver', 'san mateo'];
        shops.foreach(function(shop, idx){
          shop.city = cities[idx%2];
        });
      }
      coffeeshop.create(shops, cb);
    });
  }
  //create reviews
  function createreviews(reviewers, coffeeshops, cb) {
    mongods.automigrate('review', function(err) {
      if (err) return cb(err);
      var review = app.models.review;
      var day_in_milliseconds = 1000 * 60 * 60 * 24;
      review.create([
        {
          date: date.now() - (day_in_milliseconds * 4),
          rating: 5,
          comments: 'a very good coffee shop.',
          publisherid: reviewers[0].id,
          coffeeshopid: coffeeshops[0].id,
        },
        {
          date: date.now() - (day_in_milliseconds * 3),
          rating: 5,
          comments: 'quite pleasant.',
          publisherid: reviewers[1].id,
          coffeeshopid: coffeeshops[0].id,
        },
        {
          date: date.now() - (day_in_milliseconds * 2),
          rating: 4,
          comments: 'it was ok.',
          publisherid: reviewers[1].id,
          coffeeshopid: coffeeshops[1].id,
        },
        {
          date: date.now() - (day_in_milliseconds),
          rating: 4,
          comments: 'i go here everyday.',
          publisherid: reviewers[2].id,
          coffeeshopid: coffeeshops[2].id,
        }
      ], cb);
    });
  }
};

i’m still new to strongloop and loopback in general, but this makes sense. my needs were far simpler, so here is a script i came up with (and again, jordan helped me make it better) that just writes to a model in the in memory datasource.

var chalk = require('chalk');

console.log(chalk.magenta('lets seed this app!'));

/*
this script is based on: 
https://github.com/strongloop-training/coffee-time/blob/master/server/boot/create-sample-model-data.js
*/

module.exports = function(app) {

//sample data
var data = [
{
title:'content one', 
body:'body one',
posted:new date()
},
{
title:'content two', 
body:"body two",
posted:new date()
},
{
title:'content three', 
body:'body three',
posted:new date()
}
];

app.models.testcontent.create(data, function(err, records) {
if (err) { return console.log(chalk.red(err.message)); }
console.log(chalk.magenta('done seeding data, '+records.length+' records created.'));
});

}

pretty simple, and it works nicely.

but wait — there’s more!

so, as i said up top, a few hours after posting this, rand mckinney from strongloop shared this link with me: data persistence . in this doc, they mention that you can simply specify a json file for the datasource and the in memory data will persist to it. like, seriously, exactly what i had wanted. here is an example:

{                                                                                       
  "db": {
    "name": "db",
    "connector": "memory",
    "file": "mydata.json"
  }
}

still—probably—a bad idea in production. but as i said, this would be incredibly useful when prototyping!