Webinar: Simplifying Persistence for Java and MongoDB

Morphia: Simplifying
Persistence for Java and
MongoDB
Jeff Yemin
Java Evangelist, 10gen

MongoDB on the JVM
• MongoDB Java Driver
– Map-based API

• JVM language integrations
– Casbah (Scala)
– Jmongo (Ruby)
– Monger (Clojure)

• ODM (Object Document Mapper)
– Morphia
– Spring Data MongoDB

Morphia
• Object Document Mapper
– Specified with annotations
– Implemented with reflection

• Fluent query and update APIs
– Runtime validation

Morphia by Example
• Model
• Test
• Output

Dependencies
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>mongo-java-driver</artifactId>
<version>2.10.1</version>
</dependency>

<dependency>
<groupId>com.google.code.morphia</groupId>
<artifactId>morphia</artifactId>
<version>0.99</version>
</dependency>

Repository
<repository>
<id>morphia</id>
<name>Morphia</name>
<url>http://morphia.googlecode.com/svn/mavenrepo/</url>
<layout>default</layout>
</repository>

Create the Datastore
Morphia morphia = new Morphia();
Mongo mongo = new Mongo();
Datastore ds = morphia.createDatastore(mongo, "test");

First Entity (model)
class Programmer {
String name;
}

First Entity (test)
Programmer programmer = new Programmer();
programmer.name= "Scott Hernandez";

ds.save(programmer);

First Entity (shell)
> db.Programmer.findOne()
{
"_id" : ObjectId("503292d51aa814c051554696"),
"className" : "demo.Programmer",
"name" : "Scott Hernandez"
}

@Id (model)
class Programmer {
@Id ObjectId id;
String name;
public void toString() {…}
}

@Id (test)

System.out.println(programmer)

@Id (toString)
Programmer{id=5032935f1aa8a8aa3485b441,
name='Scott Hernandez'}

String Id (model)
class Programmer {
@Id String githubUserName;
String name;
}

String Id (test)
programmer.githubUserName = "scotthernandez";


String Id (shell)
> db.Programmer.findOne()
{
"_id" : "scotthernandez",
}

@Entity (model)
@Entity("programmers")
class Programmer {
String name;
}

@Entity (shell)
> db.programmers.findOne()
{
}

More primitives (model)
class Programmer {
String name;
Date memberSince;
boolean active;
int followers;
}

More primitives (test)
Programmer scott = new Programmer();
scott.userName = "scotthernandez";
scott.name = "Scott Hernandez";
scott.since = dateFmt.parse("Aug 12, 2009");
scott.active = true;
scott.followers = 8;

ds.save(scott);

More primitives (shell)
{
"name" : "Scott Hernandez",
"memberSince" : ISODate("2009-08-12T04:00:00Z"),
"active" : true,
"followers" : 8
}

Primitive Array (Model)
class Programmer {
String name;
Date memberSince;
boolean active;
int followers;
List<String> following;
}

Primitive Array (test)
scott.userName = "scotthernandez";
scott.name = "Scott Hernandez";
scott.since = dateFmt.parse("Aug 12, 2009");
scott.active = true;
scott.followers = 8;
scott.following = Arrays.asList("moraes", "stickfigure");

ds.save(scott);

Primitive Array (shell)
db.programmers.findOne()
{
"active" : true,
"followers" : 8,
"following" : [
"moraes",
"stickfigure"
]
}

@Embedded (model)
class Programmer {
Name name;
Date memberSince;
boolean active;
int followers;
}

@Embedded
class Name {
String first, last;
}

@Embedded (test)
programmer.name = new Name("Scott", "Hernandez");
programmer.memberSince = dateFmt.parse("Aug 12, 2009");
programmer.active = true;
programmer.followers = 8;
programmer.following = Arrays.asList("moraes", "stickfigure");


@Embedded (shell)
{
"name" : {
"first" : "Scott",
"last" : "Hernandez"
},
"active" : true,
"followers" : 8,
"following" : [
"moraes",
"stickfigure"
]
}

@Embedded List (model)
class Programmer {
Name name;
Date memberSince;
boolean active;
int followers;
List<Repository> repositories;
}
@Embedded
class Name {
String first, last;
}
@Embedded
class Repository {
String name;
String forkedFrom;
}

@Embedded (test)
programmer.repositories = Arrays.asList(
new Repository("docs", "mongodb/docs"),
new Repository("mongo-java-driver", "mongodb/mongo-java-driver"));


@Embedded List (shell)
{
…
"repositories" : [
{
"name" : "docs",
"forkedFrom" : "mongodb/docs"
},
{
"name" : "mongo-java-driver",
"forkedFrom" : "mongodb/mongo-java-driver"
}
]
}

@Reference (model)
@Entity("repos")
class Repository {
@Id ObjectId id;
@Reference Programmer owner;
String name;
String forkedFrom;
}

@Reference (test)


Repository repo = new Repository(programmer, "docs",
"mongodb/docs");

ds.save(repo);

@Reference (shell)
> db.repos.findOne()
{
"_id" : ObjectId("503297e31aa8255abe542aaa"),
"className" : "demo.Repository",
"owner" : DBRef("programmers", "scotthernandez"),
"name" : "docs",
"forkedFrom" : "mongodb/docs"
}

Small schema change (model)
abstract class Member {
@Id String userName;
@Property("memberSince") Date since;
boolean active;
String name;
}
class Programmer extends Member {
int followers;
}
@Entity("orgs")
class Organization extends Member {
}
@Entity("repos")
class Repository {
@Id ObjectId id;
@Reference Member owner;
String name;
@Reference(lazy=true) Repository forkedFrom;
}

Small schema change (test)
//…
ds.save(scott);

// save mongodb Organization
Organization mongodb = new Organization("mongodb",
"mongodb", sdf.parse("Jan 8, 2009"));
ds.save(mongodb);

// save mongodb's docs Repository
Repository mongoDocs = new Repository(mongodb, "docs");
ds.save(mongoDocs);

// save Scott's forked docs Repository
Repository scottDocs = new Repository(scott, "docs",
mongoDocs);
ds.save(scottDocs);

Small schema change (shell)
> db.orgs.findOne()
{
"_id" : "mongodb",
"className" : "demo.Organization",
"active" : false,
"name" : "mongodb"
}
{
"active" : true,
…
}

Small schema change (shell, 2)
> db.repos.find().toArray()
[
{
"_id" : ObjectId("503298be1aa8b1d255e5d45b"),
"owner" : DBRef("orgs", "mongodb"),
"name" : "docs"
},
{
"_id" : ObjectId("503298be1aa8b1d255e5d45c"),
"owner" : DBRef("programmers", "scotthernandez"),
"name" : "docs",
"forkedFrom" : DBRef("repos",
ObjectId("503298be1aa8b1d255e5d45b"))
}
]

Find by Equality (test)
• ds.get(Programmer.class, "scotthernandez")

• ds.find(Programmer.class, "name", "Scott Hernandez")

• ds.find(Programmer.class).field("name").equal("Scott Hernandez”)

Find by Equality (logs)
• test.programmers query: { _id: "scotthernandez" }

• test.programmers query: { name: "Scott Hernandez" }

• test.programmers query: { name: "Scott Hernandez" }

Find by Range (test)
• ds.find(Programmer.class).field("followers").greaterThan(0)

• ds.find(Programmer.class).filter("followers >", 0)

• ds.find(Programmer.class).field("memberSince").lessThan(sdf.parse("Jan 1, 2010"))

Find by Range (logs)
• test.programmers query: { followers: { $gt: 0 } }

• test.programmers query: { followers: { $gt: 0 } }

• test.programmers query: { memberSince: { $lt: new Date(1262322000000) } }

Combining conditions (test)
ds.find(Programmer.class).
field("memberSince").lessThan(dateFmt.parse("Jan 1, 2010")).
field("followers").greaterThan(0)

Combining conditions (logs)
test.programmers query: {
memberSince: { $lt: new Date(1262322000000) },
followers: { $gt: 0 }
}

Find by Reference (test)

Programmer scott = new Programmer("scotthernandez")
ds.find(Repository.class).field("owner").equal(scott)

Find by Reference (logs)
test.repos query: {
owner: { $ref: "programmers", $id: "scotthernandez" }
}

@Indexed
• Annotation for fields
– value (IndexDirection)
– name (String)
– unique (boolean)
– dropDups (boolean)
– background (boolean)
– sparse (boolean)
• Examples
– @Indexed(value=IndexDirection.ASC, name="followers") int followers;
– @Indexed @Reference Repository forkedFrom;

@Indexes and @Index
• @Indexes: Annotation for types
– value (Index[])

• @Index
– value (String)
– Others same as @Indexed

• Examples
– @Indexes(@Index("since, -followers")) public class
Programmer {…}

Updating with save (test)
Programmer jeff = createJeff();
ds.save(jeff);

// jeff is following scott, so increment
// scott's followers and re-save
Programmer scott = ds.get(Programmer.class,
"scotthernandez")

scott.followers++;
ds.save(scott);

Updating with save (logs)
update test.programmers

query: {
_id: "scotthernandez",
}
update: {
className: "demo.Programmer",
followers: 9,
following: [ "moraes", "stickfigure" ],
memberSince: new Date(1250049600000),
active: true,
name: "Scott Hernandez",
}

Updating with save (shell)
{
"followers" : 9,
"following" : [
"moraes",
"stickfigure"
],
"active" : true,
}

Optimistic Concurrency (model)
@Entity
public abstract class Member {
@Id String userName;
@Property("memberSince") Date since;
boolean active;
String name;
@Version Long version;
}

Optimistic Concurrency (logs)

query: {
version: 1345497713173
}
update: {
className: "demo.Programmer",
followers: 9,
following: [ "moraes", "stickfigure" ],
memberSince: new Date(1250049600000),
active: true,
name: "Scott Hernandez",
version: 1345497718181
}

Optimistic Concurrency
(shell)
{
"followers" : 9,
"following" : [
"moraes",
"stickfigure"
],
"active" : true,
"version" : NumberLong("1345497718181")
}

UpdateOperations (test)
Programmer jeff = createJeff();
ds.save(jeff);

// increment followers of scott by one
UpdateOperations<Programmer> incrementFollowing =
ds.createUpdateOperations(Programmer.class).
inc("followers", 1);

Query<Programmer> queryForScott =
ds.find(Programmer.class, "_id", "scotthernandez");

ds.update(queryForScott, incrementFollowing);

UpdateOperations (logs)

query: {
_id: "scotthernandez"
}

update: {
$inc: { followers: 1 }
}

Web Resources
• Morphia home: http://code.google.com/p/morphia/
• Morphia user group:
https://groups.google.com/forum/?fromgroups#!forum/morphia

• Demo code: https://github.com/jyemin/morphia-demo
– Separate commit and tag for each slide, so you can play
along

Thanks!
• Jeff Yemin
– https://twitter.com/@jeffyemin
– jeff.yemin@10gen.com
– https://github.com/jyemin/

Thank You
Jeff Yemin
Engineering Manager, 10gen

Webinar: Simplifying Persistence for Java and MongoDB

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