MongoDB: Easy Java Persistence with Morphia

Morphia: Easy Java PersistenceScott Hernandez @ 10gen

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

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

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

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

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

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));

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”);

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’]}

Maps of MapsCan represent object graph/treeAlways keyed off String (field)

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

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

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

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

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

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

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()

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

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);

QueriesBased on Entity (Class)Validated (default)FluentOr and Geo SupportType Converted ParamsReusableReturned as Keys (or @Id only instances)ListIterable

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();

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?

Update Operationsset(field, val)unset(field)inc(field, [val])dec(field)add(field, val)addAll(field, vals)removeFirst/Last(field)removeAll(field, vals)

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

Questions?Checkout Morphia:http://code.google.com/p/morphiaScottHernandez@gmail.com

MongoDB: Easy Java Persistence with Morphia

More Related Content

What's hot (18)

Similar to MongoDB: Easy Java Persistence with Morphia (20)

More from Scott Hernandez (12)

Recently uploaded (20)

MongoDB: Easy Java Persistence with Morphia