Quick Start

1. Morphia depends on the following third party JARs:

1) The MongoDB java driver (see the required version for each Morphia Release )

2) Optional (but needed if you use Maven)

2. If you use Maven to manage your project, you can reference Morphia as a dependency:

Repo: http://morphia.googlecode.com/svn/mavenrepo/

Project Settings:

<dependency>
        <groupId>com.google.code.morphia</groupId>
        <artifactId>morphia</artifactId>
        <version>###</version>
</dependency>
<!-Optional Jars (for certain features) but required by maven for bulding. -->
<dependency>
        <groupId>cglib</groupId>
        <artifactId>cglib-nodep</artifactId>
        <version>[2.1_3,)</version>
        <type>jar</type>
        <optional>true</optional>
</dependency>
<dependency>
        <groupId>com.thoughtworks.proxytoys</groupId>
        <artifactId>proxytoys</artifactId>
        <version>1.0</version>
        <type>jar</type>
        <optional>true</optional>
</dependency>

3. If we want to save instances of these objects to MongoDB, you need to add the Morphia annotations @Entity to the class we want to persist. We can annotate the member filed of the class with @Embedded if it doesn’t have a life outside that class. All the basic fields are automatically mapped by Morphia. If you want to exclude a field, just annotate it with @Transient .

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4. The "id " value can be any persist-able type; like an int, uuid, or other object. If you want an auto-generated value just declare it as an ObjectId . If you don't use an ObjectId you must set the value before saving.

5. Mapping the classes at the beginning of your application is a good practice. It allows the system to validate your classes and prepare for storing the data, and retrieving it:

Mongo mongo = ...;
Morphia morphia = new Morphia();
morphia.map(Hotel.class).map(Address.class);
Datastore ds = morphia.createDatastore(mongo, "my_database");

6. We can use the Datastore instance to save classes with MongoDB:

Hotel hotel = new Hotel();
hotel.setName("My Hotel");
…

Address address = new Address();
address.setStreet("123 Some street");
…

hotel.setAddress(address);
Morphia morphia = ...;
Datastore ds = morphia.createDatastore("testDB");
ds.save(hotel);

7. Load a Hotel from Mongo:

String hotelId = ...; // the ID of the hotel we want to load

// and then map it to our Hotel object
Hotel hotel = ds.get(Hotel.class, hotelId);

8. Load a Hotel using a query:

// it is easy to get four-star hotels.
List<Hotel> fourStarHotels = ds.find(Hotel.class, "stars >=", 4).asList();
//or
fourStarHotels = ds.find(Hotel.class).field("stars").greaterThenEq(4).asList();

9. In a web application environment, we would probably inject the Mongo, Morphia, and Datastore instances into a DAO/Service, and then inject that into a controller, so the controller would never directly deal with Mongo or Morphia:

public class HotelDAO extends BasicDAO<Hotel, String> {
    public HotelDAO(Morphia morphia, Mongo mongo ) {
        super(mongo, morphia, "myDB");
    }
}

HotelDAO hDAO = ...
hDAO.save(new Hotel(...));

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