Tips and tricks for using MongoDB and Node.js

1. A Guide to the MEAN Stack
Tips and Tricks for using MongoDB and NodeJS
in overwhelmingly awesome ways
Valeri Karpov
CTO, Ascot Project
www.thecodebarbarian.com
@code_barbarian
github.com/vkarpov15

2. What is The Ascot Project?
Making fashion geek-friendly
Less like this More like this

3. Who is this guy?
- Academy for Telecommunications and
Computer Science '07, Princeton CS '11
- Co-founder and CTO, SCVNGR in '08
- Google intern '09, mentored by Misko
Hevery
- Tower Research Capital '11 – '13
- Developed Ascot Project at AngelHack
DC in '12

4. What is this all about?
- Why Ascot uses MongoDB
- What's the MEAN stack and why its awesome
- How MongoDB fits in the MEAN stack
- Why MongooseJS is important and tradeoffs in it's usage
- Example of a cool MEAN stack web app

5. Why MongoDB?
1) It's cool
2) No joins for nested data
3) Flexible and simple

6. SQL is Annoying

7. MEAN Stack
Web dev framework for NodeJS
Superheroic frontend framework
Event-based concurrency environment

8. MEAN Stack – Why do I care?
- Write one language
- With MongoDB and Mongoose, easy and flexible data
validation
- With NodeJS, never need threads
- With AngularJS, dynamic client-side templates

9. Same Language, Same Objects
{ "_id" : ObjectId("5161a58b46341f8a46000003"),
"username" : "vkarpov" }
{ "_id" : "5161a58b46341f8a46000003",
"username" : "vkarpov" }
{ "_id" : "5161a58b46341f8a46000003",
"username" : "vkarpov" }

10. How MongooseJS Works
MongooseJS – code-defined schemas for MongoDB + NodeJS
- MongoDB and NodeJS are best friends
- No built-in schemas or validation
- But, MongoDB native wrapper for NodeJS is lacking:

11. How MongooseJS Works
MongooseJS – code-defined schemas for MongoDB + NodeJS
Primary MongooseJS types:
- Schema – structure defining how documents look
- Connection – Wrapper around database connection
- Model = Schema + Connection + collection name
- Document is an instantiation of a Model

12. How MongooseJS Works
A Basic MongooseJS Schema

13. How MongooseJS Works
Using the StockPrice Model

14. How MongooseJS Works
Sometimes being able to save anything isn't right

15. How MongooseJS Works
Helpful Error Messages
- Nested JSON errors
summary
- Can use this for very
generic form validation
- More on this later

16. How MongooseJS Works
Nesting and populating MongooseJS Schemas – an important
distinction that doesn't exist in SQL
Populate – similar to SQL join
Nest – re-use schema in another
schema

17. How MongooseJS Works
Can't do multi-level population!

18. How MongooseJS Works
Nesting and populating MongooseJS Schemas
When can we use nested schemas?
Many-to-one
One-to-many
One-to-one
Many-to-many

19. MEAN Stack Superpowers
NodeJS is not just a Javascript web server
- Event based concurrency
- Package manager similar to Rails gems
- Makes multithreaded servers easy

20. Example: Bitcoins!

21. Bitcoin P&L
Step 1 : Web app to display a streaming Bitcoin ticker
- Complex problem – multiple threads, sockets, mutex, etc.
- People in HFT get paid crazy money to do this in C++

22. Bitcoin P&L
- Enter NodeJS, where this is a back-of-napkin type problem

23. Bitcoin P&L
- Update frontend periodically? AngularJS makes it easy

24. Bitcoin P&L
Takeaways
- General problem : your server connecting to other servers
- Example : Ascot links
- Can write multi-threaded servers, but why?
- General problem : updating page without reload
- AngularJS two-way data binding

25. Bitcoin P&L + MongoDB
Model – list of nested stock schemas Routes – get list of stocks, add a new stock

26. Bitcoin P&L + MongoDB
AngularJS – generic no-reload form wrapper

27. Bitcoin P&L + MongoDB
Jade – A View To A Kill And the result:

28. Takeaways
- MEAN Stack is awesome
- Sophisticated frontends
- Multithreaded backends made easy
- MongooseJS helps NodeJS and MongoDB play nice
- Limitations on MongooseJS population

29. Thanks for Listening!
Further Reading
- Ascot Project : www.ascotproject.com
- AngularJS Form Validation : “How to Easily Validate Any Form
Ever Using AngularJS” @ www.thecodebarbarian.com
- SocketIO Bitcoin Price Streaming : mtgox-socket-client on NPM
and Github
- Bitcoin realtime P&L : github.com/vkarpov15/bitcoin-pnl,
coming soon to www.thecodebarbarian.com