How to force FlexJson in java to deserialize a json object to a string?

Question

So I'm getting an object back from a server that looks like this:

{
    "Status": {
        "stuff":"stuff...";
        "morestuff":"morestuff...";
        };
    "Data": { ... another object ... };
}

However, when I get this object back, I want to deserialize it to a java class that looks like this:

class Response
{
    public StatusObject Status;
    public String Data;
}

But FlexJson sees an object as the data attribute and then tries to cast a HashMap to my Data string. If I get a response back with 'null' as the Data attribute, everything works just fine (since you can assign null to a String).

How do I go about telling FlexJson to not try to make a HashMap out of the Data attribute and just take it as a String (even if it is a JSON object)?

Right now my deserialization line of code looks like this:

formattedResponse = new JSONDeserializer<network.Response>()
                    .use( "values", network.Response.class )
                    .deserialize(JSONString, network.Response.class);

Thank you for any help!

So you have to tell it 3 times? Greeeaaaat – Jan 18 '14 at 19:37 — , Jan 18 '14 at 19:37

score 2 · Accepted Answer · answered Feb 20 '12 at 20:46

2

That's difficult because it parses the JSON into an intermediate form before it starts binding it into the object. So it's already parsed into a HashMap before it starts interrogating the object for what types it should use. If you wanted to put it into a string you'll have turn it back into JSON. You can do that using a ObjectFactory and binding that onto the path in your object. Inside the ObjectFactory it could then turn that into the string and bind that into the object there.

new JSONDeserializer<...>()
    .use( "values", Response.class )
    .use( "values.Data", new JSONStringTransformer() )
    .deserialize( json, Response.class );

answered Feb 20 '12 at 20:46

chubbsondubs

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So JSONStringTransformer should be a custom ObjectFactory that I make? I'll look around at how to make custom object factories. Thanks for the help! There's no way the default StringTransformer would work? even if I try to use that I get this error: The method use(String, ClassLocator) in the type JSONDeserializer is not applicable for the arguments (String, StringTransformer) – Nico Feb 20 '12 at 22:58
No StringTransformer won't work because Transformers are used to translate Objects into JSON. You need something that takes JSON into Objects which is ObjectFactory. But the classes that converts things into Strings isn't going to know how to translate a HashMap into a String. This is a very strange situation where you don't want to take in a portion of the JSON as objects, and instead use the JSON portion string instead. – chubbsondubs Feb 21 '12 at 01:09
Ah all right, so what I'm doing is pretty backwards then. I tried to mess around with creating a custom object factory but it seemed pretty nasty so I just ended up doing this: int dataIndex = JSON.indexOf(dataIdentifier); formattedResponse.Data = JSON.substring(dataIndex + dataIdentifier.length() - 2, JSON.length() - 1); Where dataIdentifier is = "\"},\"Data\":{\""; This is pretty nasty but it works. – Nico Feb 21 '12 at 01:54
Well even if you could've gotten it to translate the HashMap back to JSON. I was going to suggest just substring'ing it because that would be a lot more efficient. – chubbsondubs Feb 22 '12 at 14:52
Yeah this solution works fine for now. Out of curiosity, if you have objects in objects, does flexjson make hashmaps of hashmaps? – Nico Feb 22 '12 at 15:00
Yes during the intermediate stage. Then it binds the contents of those hash maps into your static typed objects you want. – chubbsondubs Feb 22 '12 at 15:29

score 0 · Answer 2 · answered Jun 20 '14 at 14:40

I had the same silly problem but I went down the road of writing my own ObjectFactory to solve it.

package mypackage

import flexjson.JSONSerializer;
import flexjson.ObjectBinder;
import flexjson.ObjectFactory;

import java.lang.reflect.Type;

public class JSONStringFactory implements ObjectFactory {
    @Override
    public Object instantiate(ObjectBinder objectBinder, Object o, Type type, Class aClass) {
        return new JSONSerializer().deepSerialize(o);
    }
}

In the client code you just have to use the factory like that:

MyDomainClass foo = new JSONDeserializer<MyDomainClass>()
    .use("sillyJSONField", new JSONStringFactory())
    .deserialize(requestJson, MyDomainClass.class);

How to force FlexJson in java to deserialize a json object to a string?

2 Answers2