twirl

Yet Another Google App Engine Datastore ORM with a twirl! (We need your support, fork it, and try it)

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  :: twirl :: Object Mapping ::

twirl aims to provide a lightweight Object mapping framework. Without adding complexity into the api.

Persisting POJO's, Maps and (soon Primitive types) directly into the Datastore.

Sample

Usage sample can be found here: https://github.com/kerbymart/twirl-appengine-guestbook-java

Setup

@Inject
ObjectStore store;

Friend friend = createComplexFriend();

Key key = store.put(friend);

Friend saved = store.get(Friend.class, friend.getId()); 

Iterator<Friend> all = store.find(Friend.class).greaterThanOrEqual("name", "Joe").now();

Friend one = store.findOne(Friend.class).greaterThanOrEqual("name", "Joe").now();

Note that you can also use static import for store:

import static com.dotweblabs.twirl.ObjectStoreService.store;

store().put(friend);

Updating

Save

Passing an object to the put(..) method will do the job.

Friend joe = new Friend("Joe", 27);

store.put(joe);
joe.age = 28;
store.put(joe);

Update

store.update(Friend.class).equals("name", "Joe").increment("age",1).now();
store.update(Friend.class).equals("name", "Joe").set("address", new Address(...)).now();
store.update(Friend.class).equals("name", "Joe").with(new Friend(..)).now();

Insert

store.put(new Friend(..));
store.put(new Friend(..), new Friend(..));

Remove

store.delete(key);
store.delete(friend.getId());

Object Mapping

@Entity(name="CloseFriends") // Optional name
public class Friend {
    @Id
    private long id; // Can be long, Long or String only

    @Parent
    private Circle circle;

    @Child
    private Box box;

    @Embedded
    private Map map;

    private List<String> notes; 
}

Querying

Find & FindOne

Iterator<Friend> all = store.find(Friend.class).greaterThanOrEqual("name", "Joe").now();
Friend one = store.findOne(Friend.class).greaterThanOrEqual("name", "Joe").now();

Projection and Field selection

store.find(Friend.class).projection("firstName", "address").greaterThanOrEqual("name", "Joe").now();

Sorting

store.find(Friend.class).sortAscending("firstName").now();
store.find(Friend.class).sortDescending("lastName").now();

Skip and Limit

store.find(Friend.class).skip(20).now();
store.find(Friend.class).limit(10).now();

Cursors

String cursor = getRequestFromWebQuery();

// Should be empty String 
// or valid cursor String only
Cursor startCursor = new Cursor(cursor);

ListResult<Post> posts = store.find(Post.class)
        .limit(10)
        .withCursor(startCursor) 
        .sortAscending("date")
        .asList();

Cursor nextCursor = posts.getCursor();
return nextCursor.getWebSafeString();;

Features

Easy for JSON storage

// Note: Working but needs more work:
String jsonString = "{\"content\" : {\"Sample post\"}";
Map deserialized = deserialize(jsonString);
deserialized.put("__kind__", "Post");
store.put(deserialized);

Or using a POJO :

public class JSONEntity {
    @Kind
    private String kind;
    @Id
    private String id;
    @Flat
    private Map<String,Object> fields;
}

JSONEntity entity = new JSONEntity();

entity.setKind("Post");
entity.setId("msgid:456");
entity.getFields().put("content", "Sample post");
entity.getFields().put("uid", 123);

store.put(entity);

Storing Primitive and Basic Java types

Using the keyvalue-extenstion:

KeyValueStore<String,String> messages = new StringKeyValueStore("Messages");
messages.put("uid:123:msgid:456", "Ahoy! We are saving primitives.");
String message = messages.get("uid:123:msgid:456");

See: https://github.com/dotweblabs/twirl-keyvalue-extension

Version

0.0.1

Tech

twirl uses a number of open source projects to work properly:

[GAE SDK] - SDK for the AppEngine platform (GAE, AppScale or CapeDwarf)
boon

Installation

mvn clean install

or add this to your POM:

Repository

        <repositories>
            <repository>
                <id>dropbox.repo</id>
                <url>http://maven.weblabs.ph/mvn-repostory</url>
            </repository>
        </repositories>

From JFrog (not updated ATM):

        <repositories>
            <!-- Snapshot repository -->
            <repository>
                <id>oss-jfrog-artifactory-snapshots</id>
                <name>oss-jfrog-artifactory-snapshots</name>
                <url>http://oss.jfrog.org/artifactory/oss-snapshot-local</url>
            </repository>
        </repositories>

Dependency

        <dependency>
            <groupId>com.dotweblabs</groupId>
            <artifactId>twirl</artifactId>
            <version>0-SNAPSHOT</version>
        </dependency>

Contribution

Anyone is welcome to contribute, implement feature or fix bugs.

License

Apache License, Version 2.0

dotweblabs / twirl

readme