MongoDB Israel June Meetup
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This document summarizes a presentation about new features in MongoDB 2.6 and how they can be used in Node.js web applications. It discusses text search, the $min and $max update operators, and the $out aggregation operator. Examples are provided of implementing each feature in a Nutrition app built with the MEAN stack to allow searching for food items, conditionally updating data, and aggregating data into a new collection.
MongoDB Israel June Meetup
- 1. MongoDB 2.6 Features in NodeJS Web Apps Valeri Karpov Software Engineer, MongoDB www.thecodebarbarian.com www.slideshare.net/vkarpov15 github.com/vkarpov15 @code_barbarian
- 2. * Who Am I? •CI/NodeJS Engineer at MongoDB •Maintainer of mongoose ODM •Blogs at thecodebarbarian.com
- 3. * Talk Overview •MongoDB 2.6 released in April (currently 2.6.2) •Exciting new features including: • Text search • $min and $max operators for updates • $out operator for aggregation •Examples of use cases in NodeJS Single Page App
- 4. * Additional Tools •MongoDB NodeJS Driver •Mongoose: ODM for NodeJS, convenience wrapper around mongodb driver •Express: lightweight server MVC for NodeJS
- 5. * More Minor Tools •Moment: elegant wrapper around clunky JS Date •Omni: dependency injector for NodeJS •AngularJS: client-side MVC framework • Don’t worry if you don’t know AngularJS, won’t be used much in this presentation
- 6. * The App We’ll Be Using •Open source food journal, LeanMEAN •Counts calories, computes ratios, etc. •MEAN = MongoDB, ExpressJS, AngularJS, NodeJS
- 7. * The App We’ll Be Using - Demo
- 8. * App Overview •3 models: FoodItem, User, Day •Day = list of FoodItems a User ate on a given date
- 9. * What a FoodItem looks like •From USDA SR-25 data set •FoodItem: description, list of nutrients and weights
- 12. * Simple SR-25 Query •How many carbs in 1 serving of raw kale?
- 13. * Part I: Text Search •Problem: searching for FoodItems •Don’t want user to have to type exactly “Kale, raw” •Would be ideal if “raw kale” matched “Kale, raw”
- 14. * Example of Text Search in Shell •Top 3 results for “grass-fed beef”
- 15. * Text Search Details •Need to create a text index: • db.nutrition.ensureIndex({ description : "text" }); •Need MongoDB server >= 2.6.0 •Can specify language (15 supported languages) • db.nutrition.ensureIndex({ description : "text" }, {default_language:"ru"}); • Supports English and Russian, but no Hebrew yet •Limitation: 1 text search index per collection
- 16. * Text Search In NodeJS •Recommend using: • node-mongodb-native >= 1.4.0 (1.2 and 1.3 seem to work) • mongoose >= 3.8.9 •Since JS, very similar to shell
- 17. * Use Case For Text Search •Autocomplete/typeahead for entering food items
- 18. * The API Endpoint in Express •All our API methods:
- 19. * Search API Implementation Note: text search API is atypical, docs here
- 20. * A Note on $meta and Text Score
- 21. * Part II: $min and $max •Mongoose users often update docs in memory •Not necessarily good practice! •Just use update() where possible •$min and $max enable new use case for update() •Not to be confused with aggregation $min/$max •Not to be confused with query modifier $min/$max
- 22. * Using $min and $max in the Shell •Conditional update: • $min: only update if new value < old value • $max: only update if new value > old value
- 23. * More Interesting Use Case for $min •$min and $max also work on ISODate •Common use case: oldest piece of data for user •In LeanMEAN, user can enter data for past days •Inexpensive query, but 0 queries better than 1 •Save an HTTP request and a query = win •Tradeoff: extra load when saving
- 24. * Using $min and $max in NodeJS •No known restrictions •Still recommend • node-mongodb-native >= 1.4.0 • mongoose >= 3.8.0
- 25. * Taking a Look at the User Schema
- 26. * $min in Action with Mongoose
- 27. * Notes about $min and $max •$min and $max use BSON comparison order •Can have unexpected results! •Example: null < 4 • • •
- 28. * Notes about $min and $max, cont •$min and $max use BSON comparison order •Example: ISODate > 4 Careful to use $min/$max with right type!
- 29. * Part III: Aggregation $out •Before MongoDB 2.6, aggregation limited to 16MB •Also no good way to output to collection •2.6.0 solves both! •Aggregation returns a cursor, no fixed limit on size •$out stage outputs agg. results to collection
- 30. * Using $out from the Shell •$out is pipeline stage, like $group, $match, etc. •Takes string input: name of collection
- 31. * Using $out from the Shell: Data
- 32. * Running $out from the Shell
- 33. * Using $out in NodeJS •node-mongodb-native >= 1.4.0 recommended •mongoose >= 3.8.0 recommended •But .out() aggregation helper requires >= 3.8.9
- 34. * Use Case: All I Need is One Document •Ideal MEAN stack world: 1 document ⇔ 1 page •NodeJS makes scheduling aggregations easy •Use $out to build complex data sets with ease
- 35. * Average Calories Per Week Per User •Show week by week average calories per day •Bulky, complex aggregation •Don’t want to do this on-demand •Use node-cron to run aggregation once per day
- 36. * The Actual Aggregation, 1-3 •6 stages + $out
- 37. * The Actual Aggregation, 4-5
- 38. * The Actual Aggregation, 6-7
- 39. * Accessing via API Endpoint
- 40. * Notes on $out •Always creates a new collection •Overwrites existing collection, no append mode yet •Under the hood: • Puts aggregation output into temp collection • Atomic rename of collection after complete •Old data still available during aggregation •Temp collection inserts go in oplog and replicate •Can’t $out to a sharded or capped collection
- 41. * Thanks for Listening! •Slides on: • Twitter: @code_barbarian • Slideshare: slideshare.net/vkarpov15 •Repo on github: github.com/vkarpov15/lean-mean- nutrition •Blog post on SR-25 data set