java - Play Framework 2.1 ebean construction -

i started using play framework 2.1.1 java developer.

got ebeans existing database , i'm building restful architecture serve , save beans restful client web application.

i have following beans definitions. feed core object of application. simplicity have not included getters , setters , many other beans, i'm focusing on ones give me troubles:

@entity public class feed extends model implements serializable {     @id     long feedid;     ...     ...     ...     @jsonmanagedreference("feed-item")     @onetomany(fetch = fetchtype.lazy, mappedby = "feed")     list<item> items;     @jsonmanagedreference("feed-userfeed")     @onetomany(fetch = fetchtype.lazy, mappedby = "feed")     list<userfeed> userfeeds; }  @entity public class item extends model implements serializable {     @id     long itemid;     ...     ...     ...     long urlid;     @manytoone(fetch = fetchtype.lazy)     @joincolumn(name = "url_id")     url url;     @formats.datetime(pattern = "yyyy-mm-ddthh:mm:ss")     timestamp itempublishedat;     @formats.datetime(pattern = "yyyy-mm-ddthh:mm:ss")     timestamp itemupdatedat;     @formats.datetime(pattern = "yyyy-mm-ddthh:mm:ss")     timestamp createdat;     @version     timestamp updatedat;     long feedid;     @manytoone(fetch = fetchtype.lazy)     @jsonbackreference("item-feed")     @joincolumn(name = "feed_id")     feed feed;     long urlid;     @manytoone(fetch = fetchtype.lazy)     @joincolumn(name = "url_id")     url url;     @onetomany(fetch = fetchtype.lazy, mappedby = "item")     @jsonmanagedreference("item-unseen")     list<unseen> unseen;     @onetomany(fetch = fetchtype.lazy, mappedby = "item")     @jsonmanagedreference("item-score")     list<score> scores; }  @entity public class user extends model implements serializable {     @id     long userid;     ...     ...     ...     @onetomany     @jsonmanagedreference("user-userfeed")     list<userfeed> userfeeds;     @onetomany     @jsonmanagedreference("user-usertag")     list<usertag> usertags;     @onetomany     @jsonmanagedreference("user-unseen")     list<unseen> unseen;     @onetomany     @jsonmanagedreference("user-score")     list<score> scores; }  @entity public class score extends model implements serializable {     @id     long scoreid;     ...     ...     ...     long itemid;     @manytoone(fetch=fetchtype.lazy)     @jsonbackreference("score-item")     @joincolumn(name = "item_id")     item item;     long userid;     @manytoone(fetch=fetchtype.lazy)     @jsonbackreference("score-user")     @joincolumn(name = "user_id")     user user; } 

here's feed controller:

import me.zenfeed.model.feed;  import org.codehaus.jackson.jsonnode;  import play.db.ebean.model; import play.libs.json; import play.mvc.bodyparser; import play.mvc.controller; import play.mvc.result;  public class feedcontroller extends controller {     public static result delete(long id)     {         new model.finder<>(long.class, feed.class).byid(id).delete();         return ok();     }      /* return json of objects found*/     public static result get()     {         return ok(json.tojson(new model.finder<>(long.class, feed.class).fetch("userfeeds", new fetchconfig().query()).where().eq("userfeeds.userid", long.parselong(session("connecteduserid"))).findlist()));     }      /* accept json object save , return json new object*/     @bodyparser.of(bodyparser.json.class)     public static result post()     {         jsonnode json = request().body().asjson();         feed f = json.fromjson(json, feed.class);         f.save();         return ok(json.tojson(f));     }      /* accept json object save , return json new object*/     @bodyparser.of(bodyparser.json.class)     public static result put(long id)     {         jsonnode json = request().body().asjson();         feed f = json.fromjson(json, feed.class);         f.update(id);         return ok(json.tojson(f));     } } 

here's custom function use make query on db parameters:

list<item> l = new model.finder<>(long.class, item.class) .select("itemid, feedid, urlid, title, description, content, author, categories, itempublishedat, itemupdatedat, wordcount, fresh, vector, createdat, updatedat") .fetch("unseen", "itemid", new fetchconfig().query()) .fetch("scores", "score", new fetchconfig().query()) .fetch("feed.userfeeds", "userid", new fetchconfig().query()) .where() .eq("feed.userfeeds.userid", long.parselong(session("connecteduserid"))) .eq("feed.feedid", feedid) .orderby("scores.score") .findlist(); 

i have several problems with:

- when try post request calls method post() of controller following exception: [runtimeexception: org.codehaus.jackson.map.jsonmappingexception: can not handle managed/back reference 'user-score': no reference property found type [collection type; class java.util.list, contains [simple type, class me.zenfeed.model.score]]] think put reference in score model correctly, don't understand... ebeans correct? there wrong in controller? can made better?

i understand saw wrong tutorial. argument @jsonmanagedreference , @jsonbackreference must same. feed-item relationship correct annotations @jsonmanagedreference("feed-item") , @jsonbackreference("feed-item").

• as can see tried format timestamp objects html5 format, no luck. long number. should make conversion date object? if yes where?

- when run query custom function url object populated, though excluded select statement (i url_id, not entire object).

i went manual way generation of hashmap properties care of , gave json.tojson() method.

thank help.