This document provides an overview of Morphia, a Java object mapping library for MongoDB. It discusses Morphia's advantages over using raw MongoDB drivers, including type safety and the ability to work with POJOs rather than generic maps. Key features covered include annotation-based mapping of entities to collections, lifecycle callbacks, queries, updates, and support for relationships and object graphs. The document aims to demonstrate how Morphia reduces boilerplate and provides a more object-oriented interface for working with MongoDB in Java applications.

1. Morphia: Easy Java PersistenceScott Hernandez @ 10gen

2. Library ChoicesRaw MongoDB DriverMap<String, Object> view of objectsRough but dynamicMorphia (type-safe mapper)POJOsAnnotation based (similar to JPA)Syntactic sugar and helpersOthersCode generators, other jvm languages

3. MongoDB Java DriverBSON PackageTypesEncode/DecodeDBObject (Map<String, Object>)Nested MapsDirectly encoded to binary format (BSON)MongoDB PackageMongoDBObject (BasicDBObject/Builder)DB/DBColletionDBQuery/DBCursor

4. BSON PackageTypesint and longArray/ArrayListStringbyte[] – binDataDouble (IEEE 754 FP)Date (secs since epoch)NullBooleanJavaScript StringRegex

5. MongoDB PackageMongoConnection, ThreadSafeWriteConcern*DBAuth, Collections getLastError()Command(), eval()RequestStart/DoneDBCollectionInsert/Save/Find/Remove/Update/FindAndModifyensureIndex

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

7. Simple Example, AgainDBCollectioncoll = 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. ListsDBObjectdbObj = 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 MapsCan represent object graph/treeAlways keyed off String (field)

11. Morphia: MongoDB MapperMaps POJO (through fields)Type-safe/preservingAccess Patterns: DAO/Datastore/+moreData TypesPerforms wellJPA likeMany concepts came from Objectify (GAE)

12. Annotations@Entity(“collectionName”)@Id@Reference[@Embedded]@Serialized@Transient – not java transient@Property(“fieldAlias”)

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

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

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

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

17. Datastore Basicsget(class, id) – single Entity by idfind(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 fieldsPush/pop arrays (lists)Increment numeric fieldsAny combination of the aboveMergeGet/Save or Update

19. Add, Get, DeletePerson 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. QueriesBased on Entity (Class)Validated (default)FluentOr and Geo SupportType Converted ParamsReusableReturned as Keys (or @Id only instances)ListIterable

21. Simple QueryDatastoreds = …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. UpdateDatastoreds = …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 Operationsset(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 EntityUpdate@ReferenceStored as DBRef(s)Loaded with EntityNot automatically savedLazy (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/morphiaScottHernandez@gmail.com