MongoDB Persistence with Java and Morphia

Software Engineer, MongoDB

Justin Lee

AgendaIntroduction

Getting Started

Modeling

Querying

Updating

Indexing

Road Map

What is Morphia?• Object document mapper — https://github.com/mongodb/morphia

• Provides mapping to/from Java objects to mongodb

• Annotation-based

• Embedded objects/documents

• References (lazy or eager)

• Fluent query/update APIs

• Runtime validation

Why Morphia?• Offload object marshaling

• automatically keeps up as objects evolve: new, removed, renamed

• Higher abstraction

• Simplified management of indexes

• Unify code with schema management

• Object/Document Versioning

A Brief History

• Created by Scott Hernandez

• Hired by 10Gen —> started working on the kernel

• Morphia left alone for a couple of years

• Lots of uncertainty

• James Green forked morphia

• I was hired in June, 2013 in part to pick up Morphia

• 5 releases since with another pending

Getting Started

Adding morphia — Maven

<dependency>

<groupId>org.mongodb.morphia</groupId>

<artifactId>morphia</artifactId>

<version>0.105</version>

</dependency>

<dependency>

<groupId>org.mongodb</groupId>

<artifactId>mongo-java-driver</artifactId>

<version>2.11.3</version>

</dependency>

Adding morphia — Gradle

compile "org.mongodb.morphia:morphia:0.105"

compile "org.mongodb:mongo-java-driver:2.11.3"

!

!

Initializing morphia

Morphia morphia = new Morphia();

Datastore datastore = morphia.createDatastore(

new MongoClient(), “morphia-demo");

morphia.mapPackage("org.mongodb.morphia.demo");

datastore.ensureIndexes();

!

Entity Modeling

Basic Entity

@Entity

public class GithubUser {

private String userName;

private String fullName;

!

private Date memberSince;

}

Basic Entity

@Entity

public class GithubUser {

private String userName;

private String fullName;

!

private Date memberSince;

}

(value = “users")

Basic Entity

@Entity

public class GithubUser {

private String userName;

private String fullName;

!

private Date memberSince;

}

(value = "users", noClassnameStored = true)

Basic Entity

@Entity

public class GithubUser {

private String userName;

private String fullName;

!

private Date memberSince;

}

(value = "users", noClassnameStored = true)

@Id

Basic Entity

@Entity

public class GithubUser {

private String userName;

private String fullName;

!

private Date memberSince;

}

(value = "users", noClassnameStored = true)

@Id

@Property("since")

Basic Entity — Saving

GithubUser user = new GithubUser("evanchooly");

user.fullName = "Justin Lee";

user.memberSince = sdf.parse("6-15-1987");

datastore.save(user);

Basic Entity — Shell

repl0:PRIMARY> db.users.findOne() { "_id" : "evanchooly", "fullName" : "Justin Lee", "since" : ISODate("1987-06-15T04:00:00Z") }

Complex Entities

@Entity("orgs") public class Organization { @Id public String name; ! public Organization(final String name) { this.name = name; } }

Complex Entities

@Embedded public class Settings { public String defaultBranch = "master"; public Boolean allowWiki = false; public Boolean allowIssues = true; }

Complex Entities

@Entity("repos") public class Repository { @Id public String name; @Reference public Organization organization; @Reference public GithubUser owner; public Settings settings = new Settings(); }

Complex Entities

@Entity(value = "users", noClassnameStored = true) public class GithubUser { @Id public final String userName; public String fullName; @Property("since") public Date memberSince; @Reference(lazy = true) public List<Repository> repositories = new ArrayList<>(); }

Complex Entities

Organization org = new Organization("mongodb"); !GithubUser user = new GithubUser("evanchooly"); user.fullName = "Justin Lee"; user.memberSince = sdf.parse("6-15-1987"); !datastore.save(org); datastore.save(user); !datastore.save(new Repository(org, "morphia")); datastore.save(new Repository(user, "morphia"));

Complex Entities — Shell

repl0:PRIMARY> show collections orgs repos system.indexes users

Complex Entities — Shell

repl0:PRIMARY> db.orgs.findOne(); { "_id" : "mongodb", "className" : "org.mongodb.morphia.demo.Organization" }

Complex Entities — Shellrepl0:PRIMARY> db.repos.find().pretty(); { "_id" : "mongodb/morphia", "className" : "org.mongodb.morphia.demo.Repository", "organization" : DBRef("orgs", "mongodb"), "settings" : { "defaultBranch" : "master", "allowWiki" : false, "allowIssues" : true } } { "_id" : "evanchooly/morphia", "className" : "org.mongodb.morphia.demo.Repository", "owner" : DBRef("users", "evanchooly"), "settings" : { … } }

Complex Entities — Shell

repl0:PRIMARY> db.users.findOne(); { "_id" : "evanchooly", "fullName" : "Justin Lee", "since" : ISODate("1987-06-15T04:00:00Z"), "repositories" : [ DBRef("repos", "mongodb/morphia"), DBRef("repos", "evanchooly/morphia") ] }

Queries

Basic Query

Query<Repository> query = datastore.createQuery(Repository.class); Repository repository = query.get(); !runQuery called morphia-demo.repos {} !List<Repository> repositories = query.asList(); !runQuery called morphia-demo.repos {} !Iterable<Repository> fetch = query.fetch(); !… ?

Basic Query

Query<Repository> query = datastore.createQuery(Repository.class); query.field("owner").equal(evanchooly).get(); !runQuery called morphia-demo.repos { owner: { $ref: "users", $id: "evanchooly" } }

Complex Entities

@Entity("repos") public class Repository { @Id public String name; @Reference public Organization organization; @Reference public GithubUser owner; public Settings settings = new Settings(); }

Basic Query — @Property

@Entity(value = "users", noClassnameStored = true)

public class GithubUser {

@Id

private String userName;

private String fullName;

@Property("since")

private Date memberSince;

}

Basic Query — @Property

datastore.createQuery(GithubUser.class) .field("memberSince").equal(date).get(); !GithubUser{userName='evanchooly', fullName='Justin Lee', memberSince=Mon Jun 15 00:00:00 EDT 1987} !datastore.createQuery(GithubUser.class) .field("since").equal(date).get(); !GithubUser{userName='evanchooly', fullName='Justin Lee', memberSince=Mon Jun 15 00:00:00 EDT 1987}

Updates

Updating Entities

evanchooly.followers = 12; datastore.save(evanchooly);

Multiple Updates

UpdateOperations<GithubUser> update = datastore.createUpdateOperations( GithubUser.class) .inc("followers").set("following", 42); Query<GithubUser> query = datastore.createQuery(GithubUser.class) .field(“followers”) .equal(0); datastore.update(query, update); !update morphia-demo.users query: { followers: 0 } update: { $set: { following: 42 }, $inc: { followers: 1 } }

Versioned Updates

@Entity("orgs") public class Organization { @Id public String name; @Indexed public Date created; @Version(“v”) private long version; !… !}

Versioned Updates

Organization organization = datastore.createQuery(Organization.class).get(); Organization organization2 = datastore.createQuery(Organization.class).get(); !datastore.save(organization); // fine datastore.save(organization); // fine datastore.save(organization2); !java.util.ConcurrentModificationException: Entity of class org.mongodb.morphia.demo.Organization (id='mongodb',version='1') was concurrently updated.

Indexes

Indexes — Fields

@Entity("orgs") public class Organization { @Id public String name; @Indexed(value = IndexDirection.ASC, unique = false, name = "", dropDups = false, background = false, sparse = false, expireAfterSeconds = -1) public Date created; !… }

Indexes — Fields

repl0:PRIMARY> db.orgs.getIndexes() [ { "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "morphia-demo.orgs" }, { "v" : 1, "key" : { "created" : 1 }, "name" : "created_1", "ns" : "morphia-demo.orgs" } ]

Indexes — Classes

@Entity(value = "users", noClassnameStored = true) @Indexes({ @Index(value ="userName, -followers", name = "popular") }) public class GithubUser { @Id public String userName; public String fullName; @Property("since") public Date memberSince; public Date lastActive; @Reference(lazy = true) public List<Repository> repositories = new ArrayList<>(); public int followers = 0; public int following = 0; !…

What’s Next

The Road to 1.0

• It’s short

• Aggregation support

• Text Searching

• Improved geo support

• Handful of bug fixes

Resources

• Morphia Homepage https://github.com/mongodb/morphia

• Discussions Forum https://groups.google.com/forum/#!forum/morphia

• This presentation and code https://github.com/evanchooly/morphia-demo

Questions?

MongoDB Persistence with Java and Morphia

Software Engineer, MongoDB

Justin Lee