![{
"name": "Philipp",
"isAlive": true,
"age": 30,
"height_cm": 181.5,
"address": {
"city": "Vienna",
"postalCode": "1190"
},
"phoneNumbers": [ {
"type": "mobile",
"number": "+43 123 4567890"
} ]
}](https://image.slidesharecdn.com/morphia-151007101604-lva1-app6892/85/Paintfree-Object-Document-Mapping-for-MongoDB-by-Philipp-Krenn-17-320.jpg)
Paintfree Object-Document Mapping for MongoDB by Philipp Krenn
- 1. Java Day Charkiv Painfree Object- Document Mapping for MongoDB Philipp Krenn @xeraa
- 2. Vienna
- 3. Vienna
- 4. Vienna
- 5. ViennaDB Papers We Love Vienna
- 6. Electronic Data Interchange (EDI)
- 9. Who has heard of Morphia?
- 10. Like JPA for MongoDB ...but better
- 11. @OneToMany(mappedBy = "destCustomerId") @ManyToMany @Fetch(FetchMode.SUBSELECT) @JoinTable(name = "customer_dealer_map", joinColumns = { @JoinColumn(name = "customer_id", referencedColumnName = "id")}, inverseJoinColumns = { @JoinColumn(name = "dealer_id", referencedColumnName = "id")}) private Collection<Client> dealers;
- 14. Ted Neward: ORM is "The Vietnam of Computer Science" http://blogs.tedneward.com/2006/06/26/The+Vietnam+Of+Computer+Science.aspx
- 15. MongoDB
- 16. Table = Collection Schemaless Row = Document JSON
- 17. { "name": "Philipp", "isAlive": true, "age": 30, "height_cm": 181.5, "address": { "city": "Vienna", "postalCode": "1190" }, "phoneNumbers": [ { "type": "mobile", "number": "+43 123 4567890" } ] }
- 19. List<BasicDBObject> phoneNumbers = new ArrayList<>(); phoneNumbers.add( new BasicDBObject("type", "mobile") .append("number", "+43 123 4567890")); BasicDBObject document = new BasicDBObject("name", "Philipp") .append("isAlive", true) .append("age", 30) .append("height_cm", 181.5f) .append("address", new BasicDBObject("city", "Vienna") .append("postalCode", "1190")) .append("phoneNumbers", phoneNumbers);
- 21. Morphia
- 23. Features Lightweight Type safe & preserving
- 25. Show me some code https://github.com/xeraa/ morphia-demo
- 27. $ gradle test Standalone or embedded MongoDB
- 28. Annotations
- 29. Collections
- 30. @Entity( value = "company" ) public class CompanyEntity { @Id protected ObjectId id; public CompanyEntity() { }
- 31. Do not use dashes in the collection name
- 33. Do not copy paste the value attribute
- 34. Do not use @Id as String (without reason)
- 35. Polymorphism
- 36. public abstract class EmployeeEntity { protected String name; } public class ManagerEntity extends EmployeeEntity { protected Boolean approveFunds; } public class WorkerEntity extends EmployeeEntity { protected Integer yearsExperience; }
- 37. RDBMS 1. Union table with (many) NULL values
- 38. RDBMS 2. Concrete instances without common queries
- 39. RDBMS 3. Base table joined with all subtables
- 41. @Entity(value = "employee", noClassnameStored = false) public abstract class EmployeeEntity { @Id protected ObjectId id; protected String name; } public class ManagerEntity extends EmployeeEntity { protected Boolean approveFunds; } public class WorkerEntity extends EmployeeEntity { protected Integer yearsExperience; }
- 42. { "_id": ObjectId("5461c8bf9e2acf32ed50c079"), "className": "net.xeraa.morphia_demo.entities.ManagerEntity", "name": "Peter", "approveFunds": true } { "_id": ObjectId("524d9fe7e4b0f8bd3031f84e"), "className": "net.xeraa.morphia_demo.entities.WorkerEntity", "name": "Philipp", "yearsExperience": 10 }
- 44. Properties
- 45. protected String firstname; @AlsoLoad("lastname") protected String surname; protected Boolean approveFunds; @Property("hire") protected boolean managerCanApproveHires; public EmployeeEntity setFirstname(String firstname) { this.firstname = firstname; return this; }
- 46. Do trim property names (MMAPv1)
- 47. Do use object data types
- 49. Do Or use Lombok !
- 50. Indexes
- 51. @Entity(value = "employee", noClassnameStored = false) @Indexes(@Index(name = "name", fields = { @Field(value = "surname"), @Field(value = "firstname") })) public class EmployeeEntity { protected String firstname; protected String surname; @Indexed(unique = true, sparse = false) protected String email;
- 52. Optimistic locking vs pessimistic locking in RDBMS
- 53. @Version private long version; { ... "version": NumberLong("1") }
- 54. Anti JOIN
- 55. public class EmployeeEntity { @Reference protected CompanyEntity company; @Embedded protected BankConnectionEntity bankConnection;
- 56. Queries
- 57. Save or upsert
- 58. public ObjectId persistCompanyEntity(CompanyEntity company) { mongoDatastore.save(company); return company.getId(); } public ObjectId persistManagerEntity(ManagerEntity manager) { mongoDatastore.save(manager); return manager.getId(); } public ObjectId persistWorkerEntity(WorkerEntity worker) { mongoDatastore.save(worker); return worker.getId(); }
- 59. Get data
- 60. public EmployeeEntity findByEmail(final String email) { return mongoDatastore.find(EmployeeEntity.class) .field("email").equal(email).get(); } public List<EmployeeEntity> getAllEmployees() { return mongoDatastore.find(EmployeeEntity.class).asList(); } public List<ManagerEntity> getAllManagers() { return mongoDatastore.find(ManagerEntity.class) .disableValidation() .field("className").equal(ManagerEntity.class.getName()) .asList(); }
- 61. Watch out .equal() != .equals() Trust your compiler
- 63. More queries Regular expressions .exists(), .doesNotExist() .greaterThan(), .hasAnyOf(),... .sort(), .skip(), .limit()
- 64. More features Capped collections GridFS Aggregation framework Geo locations
- 65. Patterns
- 66. Base Class
- 67. public abstract class BaseEntity { @Id protected ObjectId id; protected Date creationDate; protected Date lastChange; @Version private long version;
- 68. public BaseEntity() { super(); } // No setters public ObjectId getId() { return id; } public Date getCreationDate() { return creationDate; } public Date getLastChange() { return lastChange; }
- 69. @PrePersist public void prePersist() { this.creationDate = (creationDate == null) ? new Date() : creationDate; this.lastChange = (lastChange == null) ? creationDate : new Date(); } public abstract String toString(); }
- 70. public <E extends BaseEntity> ObjectId persist(E entity) { mongoDatastore.save(entity); return entity.getId(); } public <E extends BaseEntity> long count(Class<E> clazz) { return mongoDatastore.find(clazz).countAll(); } public <E extends BaseEntity> E get(Class<E> clazz, final ObjectId id) { return mongoDatastore.find(clazz).field("id").equal(id).get(); }
- 71. Converters
- 72. Option 1 Not readable or searchable in the database @Serialized protected BigDecimal bonus;
- 73. Option 2 Fugly @Transient protected BigDecimal salary; protected String salaryString;
- 74. @PrePersist public void prePersist() { super.prePersist(); if (salary != null) { this.salaryString = this.salary.toString(); } } @PostLoad public void postLoad() { if (salaryString != null) { this.salary = new BigDecimal(salaryString); } else { this.salary = null; } }
- 75. Option 3 Yes! @Converters({BigDecimalConverter.class}) public class WorkerEntity extends EmployeeEntity { protected BigDecimal dailyAllowance;
- 76. public class BigDecimalConverter extends TypeConverter implements SimpleValueConverter { @Override public Object encode(Object value, MappedField optionalExtraInfo) { if (value == null) { return null; } return value.toString(); } @Override public Object decode(Class targetClass, Object fromDBObject, MappedField optionalExtraInfo) throws MappingException { if (fromDBObject == null) { return null; } return new BigDecimal(fromDBObject.toString()); } }
- 78. Critter Query<Query> query = ds.createQuery(Query.class); query.and( query.criteria("bookmark").equal(bookmark), query.criteria("database").equal(database) ); QueryCriteria criteria = new QueryCriteria(datastore); criteria.and( criteria.bookmark(bookmark), criteria.database(database) ); Query query = criteria.query().get();
- 79. But is it fast?
- 81. Conclusion
- 82. Things you won't get Transactions JOINs
- 83. Things you will get Rapid development Easy replication and sharding Impedence match with rich documents
- 84. To sum up Developers ❤ Morphia
- 87. Image Credit • Schnitzel https://flic.kr/p/9m27wm • Architecture https://flic.kr/p/6dwCAe • Conchita https://flic.kr/p/nBqSHT • Paper: http://www.freeimages.com/photo/432276