[2.0] toJson infinite recursion

[drakkan]

Hi,

I have classical user and group models with a many to many relation.
I'm using ebean.

If I do something like this.

ObjectNode result = Json.newObject();
List<User> users =
User.finder.fetch("userGroups.group","id,name").findList();
result.put("Users",Json.toJson(users));

I get:

[RuntimeException: java.lang.IllegalArgumentException: Infinite
recursion (StackOverflowError) (through reference chain:
models.User["userGroups"]->com.avaje.ebean.common.BeanList[0]-
>models.UserGroup["user"]->models.User["userGroups"]-
>com.avaje.ebean.common.BeanList[0]->models.UserGroup["user"]-> ......

if instead I define a List< Map<String,Object> > and populate it
iterating over the Users, toJson works fine, is this the intended
behaviour or is there a bug in toJson?

thanks
drakkan

[Guillaume Bort]

You have cycle in your object graph (user point to group that point to
user). That's why it can't be automatically serialized to JSON.

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[Marcos Pereira]

As far as I know, XStream json mappers can handle cycles. So, maybe you can create your own json serializer to handle your object graph.

http://xstream.codehaus.org/json-tutorial.html

HTH

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[Ben McCann]

Play uses Jackson 1.  Jackson 2 can handle cycles.  You might look at upgrading Play or using your own custom serialization that's based off of Play's.  The main difference between Jackson 1 and Jackson 2 is that the package name has changed, which is pretty easy to update.

HTH

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[gaurav]

Sorry for being little dense. I am having exactly the same issue. How do I use Jackson 2 libraries instead Jackson 1. Just add the associated libs in the lib folder? Also any particular reason why play uses jackson 1 vs 2?

[Ben McCann]

I don't think it's as simple as that.  You'd probably have to submit a pull request to upgrade Play.

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[Vincent Buzzano]

I try to use FlexJson to serialize a Model, but I got all public field twice... example:

@Entity

public class Person extend Model{

    public String name

    ...

}

in my controller I do

Person p = new Person();

p.name = "My name";

JSONSerializer serializer = new JSONSerializer()

  .include("name")

  .exclude("*")

  .prettyPrint(true);

serializer.serialize(p)

I get the result:

{
  "name": "My name",
  "name": "My name"
}

How do you deal with this ?

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2012/10/22 tru3d3v <tru3...@gmail.com>

Hello Guys, i have already solve this problem just like this.

List<ExtjsDevObjects> obj = Ebean.find(ExtjsDevObjects.class).select("application,version,instance").

findList();

JSONSerializer postDetailsSerializer = new JSONSerializer().include(

                "application",

                "version","instance.instance").exclude("*");

return ok(postDetailsSerializer.serialize(obj));

verry awesome, its so simple...i am using flexjson:

http://flexjson.sourceforge.net/javadoc/index.html

you can add jar file with add this code to file Build.scala 

val appDependencies = Seq(

      // Add your project dependencies here,

//      "mysql" % "mysql-connector-java" % "5.1.21",

        "net.sf.flexjson" % "flexjson" % "2.1"   )

Good Luck :)

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[Vincent Buzzano]

Sorry about the last mail.. I was testing Version 2.0 and it 's work with version 2.1

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2013/1/7 Vincent Buzzano <vincent...@gmail.com>

[Rupanjan Baidya]

tru3d3v,


I was facing the same problem, your fix worked for me also .. thanks alot.

Thanks,
Rupanjan

On Monday, October 22, 2012 11:22:22 AM UTC+5:30, tru3d3v wrote:

Hello Guys, i have already solve this problem just like this.

List<ExtjsDevObjects> obj = Ebean.find(ExtjsDevObjects.class).select("application,version,instance").

findList();

JSONSerializer postDetailsSerializer = new JSONSerializer().include(

                "application",

                "version","instance.instance").exclude("*");

return ok(postDetailsSerializer.serialize(obj));

verry awesome, its so simple...i am using flexjson:

http://flexjson.sourceforge.net/javadoc/index.html

you can add jar file with add this code to file Build.scala 

val appDependencies = Seq(

      // Add your project dependencies here,

//      "mysql" % "mysql-connector-java" % "5.1.21",

        "net.sf.flexjson" % "flexjson" % "2.1"   )

Good Luck :)

On Sunday, April 1, 2012 5:50:59 PM UTC+7, drakkan wrote:

[tru3...@gmail.com]

Y'r welcome Rupanjan :)

Sent from my BlackBerry®
powered by Sinyal Kuat INDOSAT

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From: Rupanjan Baidya <baidya....@gmail.com>

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Date: Wed, 10 Sep 2014 13:26:50 -0700 (PDT)

To: <play-fr...@googlegroups.com>

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Subject: [play-framework] Re: [2.0] toJson infinite recursion

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