Easy java (POJO) persistence with Morphia and MongoDB.

1. Morphia: Easy Java Persistence Scott Hernandez @ 10gen

2. Library Choices Raw MongoDB Driver Map<String, Object> view of objects Rough but dynamic Morphia (type-safe mapper) POJOs Annotation based (similar to JPA) Syntactic sugar and helpers Others Code generators, other jvm languages

3. MongoDB Java Driver BSON Package Types Encode/Decode DBObject (Map<String, Object>) Nested Maps Directly encoded to binary format (BSON) MongoDB Package Mongo DBObject (BasicDBObject/Builder) DB/DBColletion DBQuery/DBCursor

4. BSON Package Types int and long Array/ArrayList String byte[] – binData Double (IEEE 754 FP) Date (secs since epoch) Null Boolean JavaScript String Regex

5. MongoDB Package Mongo Connection, ThreadSafe WriteConcern* DB Auth, Collections getLastError() Command(), eval() RequestStart/Done DBCollection Insert/Save/Find/Remove/Update/FindAndModify ensureIndex

6. Simple Example DBCollectioncoll = new Mongo().getDB(“test”); coll.save( new BasicDBObjectBuilder(“name”, “scott”). append(“sex”, “male”). append(“height”, 178)).get());

7. Simple Example, Again DBCollectioncoll = new Mongo().getDB(“test”).getCollection(“people”); Map<String, Object> fields = new … fields.add(“name”, “scott”); fields.add(“sex”, “male”); fields.add(“height”, 178); coll.insert(new BasicDBObject(fields));

8. DBObject <-> (B/J)SON {name:”scott”, sex:“male”, height: 178 } new BasicDBObjectBuilder() .append(“name”, “scott”) .append(“sex”, “male”) .append(“height”, 178) .get(); String name = (String)dbObj.get(“name”);

9. Lists DBObjectdbObj = JSON.parse(“ {‘name’:’scott’,height: 178, sex:’male’} ”); List<String> activities = new … activities.add(“mongodb”); activities.add(“java”); dbObj.put(“activities”, activities); {…, activities: [‘mongodb’, ‘java’]}

10. Maps of Maps Can represent object graph/tree Always keyed off String (field)

11. Morphia: MongoDB Mapper Maps POJO (through fields) Type-safe/preserving Access Patterns: DAO/Datastore/+more Data Types Performs well JPA like Many concepts came from Objectify (GAE)

13. Annotations -- continued @Indexes(@Index(…), @Index(…)) @Indexed(…) @AlsoLoad([aliases]) @NotSaved() @ConstructorAgs([field-names])

14. Basic POJO @Entity class Person { @Id String name; SexEnum sex; @Indexed Integer height; }

15. Lifecycle Events @PrePersist @PreSave @PostPersist @PreLoad @PostLoad @EntityListeners EntityInterceptor (global)

16. Lifecycle Methods @Entity class Person { @Id String name; … Date updated; @PrePersist void prePersist() { updated = new Date(); } }

17. Datastore Basics get(class, id) – single Entity by id find(class, […]) – multiple Entities (by query) save(entity, […]) delete(query) getCount(query) – also find(…).count() update/First(query, ops) findAndModify/Delete(query, ops) merge(doc) mapReduce(type, query, map, reduce, …) EnsureIndexes()/EnsureCaps()

18. Save whole object graphs (get/save) Update parts (embedded objects) Un/set fields Push/pop arrays (lists) Increment numeric fields Any combination of the above Merge Get/Save or Update

19. Add, Get, Delete Person me = new Person(“scott”, Sex.Male, 179) Datastoreds = new Morphia().createDatastore(“bar”) ds.save(me); Person meAgain = ds.get(Person.class, “scott”) ds.delete(me);

20. Queries Based on Entity (Class) Validated (default) Fluent Or and Geo Support Type Converted Params Reusable Returned as Keys (or @Id only instances) List Iterable

21. Simple Query Datastoreds = … Query q = ds.createQuery(Person.class); q.field(“height”).greaterThan(155).limit(5); for(Person p : q.fetch()) print(p); Person me = q.field(“name”).startsWith(“sc”).get();

22. Update Datastoreds = … Query q = ds.find(Person.class, “name”, “scott”); UpdateOperationuo = ds.createUpdateOperations(cls) uo.set(“city”, “seattle”).set(“lastUpdated”, new Date()); UpdateResults res = ds.update(q, uo); if(res.getUpdatedCount() > 0) //do something?

23. Update Operations set(field, val) unset(field) inc(field, [val]) dec(field) add(field, val) addAll(field, vals) removeFirst/Last(field) removeAll(field, vals)

24. Relationships [@Embedded] Loaded/Saved with Entity Update @Reference Stored as DBRef(s) Loaded with Entity Not automatically saved Lazy (w/proxy) Key<T> Stored as DBRef(s) Just a link, but resolvable by Datastore/Query

25. Questions? Checkout Morphia: http://code.google.com/p/morphia ScottHernandez@gmail.com