I would like to use Lift-JSON (v2.2) with Play framework to parse a JSON file into Scala case classes. I am using scala 2.8.1 and play 1.1 with scala pluging v0.8. To start I copied the code from https://github.com/lift/lift/tree/master/framework/lift-base/lift-json/ for extracting value into classes (Person class, section "Extracting values". When I browse to localhost to see the results I receive
play.exceptions.JavaExecutionException: Parsed JSON values do not match with class constructor
args=
arg types=
constructor=public controllers.Person(java.lang.String,controllers.Address,scala.collection.immutable.List)
at play.mvc.ActionInvoker.invoke(ActionInvoker.java:285)
at Invocation.HTTP Request(Play!)
Caused by: net.liftweb.json.MappingException: Parsed JSON values do not match with class constructor
args=
arg types=
constructor=public controllers.Person(java.lang.String,controllers.Address,scala.collection.immutable.List)
at net.liftweb.json.Meta$.fail(Meta.scala:128)
...
I suppose Play somehow runs scala commands in REPL mode ( the problem discussed here: http://caffiendfrog.blogspot.com/2010/11/scala-json-lift-web-trouble-with.html ). I appreciate your experience with using play and lift-json to parse/extract json objects.
I switched from lift-json to https://github.com/codahale/jerkson , problem resolved.
You should look another discussion about this problem, it seems to be explained :)
Related
I am trying to serialize a list of java Objects (POJO) into RecordIO format. I have seen this BeanIO (http://beanio.org/) but it seems to be outdated. Is there any other Java library that could be used or a different way to do this ?
Once list of objects is serialized it will be used to train a model with SageMaker.
Solving my own problem. I decided to use Apache Avro instead of BeanIO. Spark allow to serialize using Avro (c.f. Spark-Avro). This seems to work however it did not fit my use case has I was trying to serialize an array of numbers.
I need to deserialize some JSON objects. I tried to use Tiny-json library, but it's too slow. I tried to use Newtonsoft.Json, but it fails in webplayer with this error:
MissingMethodException: Method not found: 'System.Collections.ObjectModel.KeyedCollection.
What JSON parser do you recommend?
You can try one of these open source solutions:
https://github.com/jacobdufault/fullserializer
https://github.com/mtschoen/JSONObject (https://www.assetstore.unity3d.com/en/#!/content/710) I am using this one most of the times, it's versbose but does its job well, not sure about performance however
Or go with paid ones:
https://www.assetstore.unity3d.com/en/#!/content/11347
Unity 5.3 added Native support of Json Serializer. It is faster than others.
JsonUtility.ToJson to convert a class to Json.
JsonUtility.FromJson to convert Json back to class.
For complete example and information regarding json arrays, see
Serialize and Deserialize Json and Json Array in Unity
In a Play 2.0 application, I need to deserialize some JSON from a source which I don't control which uses single-quotes around strings -- where the JSON spec calls for double-quotes.
The solution using Jackson is here:
Configure Jackson to deserialize single quoted (invalid) JSON
But trying to implement this solution in play2.0 I hit a wall of static objects and private classes... it should be enough to replace object JerksonJson with one implementing the solution linked above at initialization, but because it is a static object it can't be extended, and id I try to copy it into my code I need to drag along classes PlaySerializers, PlayDeserializers, JsValueDeserializer,... I stopped here, as it looked like too much.
Is there a clean solution?
How about trying to fix the invalid json string by replacing every ' in it with a "?
That would work if 's are only used for specifying strings.
I realize that this may not help too much with Play framework part, but perhaps you could use Jackson Scala Module instead of Jerkson? Doing that should make it easier to just use ObjectMapper, with Scala module registered, instead of having to use Jerkson-specific handlers.
I am currently using the this Jackson plugin
Which serialized my cyclical graphs. Then on the client I use the JSOG to decode the {#ref} objects like this:
JSOG.decode(data)
The problem comes when I am trying to send the json back up to the server. If I don't do anything to the data I get a "Maximum call stack size exceeded", obviously because my js object is cyclical. I try using:
JSOG.stringify(data);
But then Jackson chokes on all the #id and #refs:
com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "#id"
Has any one figured out how to do this?
Both sides need to be able to support JSOG convention. It is not part of JSON specification, nor can it be automatically detected; so Jackson can not process it without help.
I'm in the process of upgrading a grails plugin from 1.3.4 to grails 2.1.1. After upgrading I now have an integration test that fails that was not failing before. It fails on using the "as JSON" (grails.converters.JSON).
#Test
public void testConvertCollectionOfEnvironmentSettingsToJSON() {
EnvironmentSetting setting = configurationService.getEnvironmentSetting('ENFORCE_SCHEMA_INSTANCE_RULE')
def jsonSetting = setting as JSON //exception thrown here
def s = jsonSetting as String
assertNotNull jsonSetting
}
The exception and stacktrace:
org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'com.company.ipsvc.configuration.domain.EnvironmentSettingAllRevs#48c12420' with class 'com.company.ipsvc.configuration.domain.EnvironmentSettingAllRevs' to class 'grails.converters.JSON'
at com.company.ipsvc.configuration.converter.json.basic.BasicEnvironmentSettingJSONIntegrationTests.testConvertCollectionOfEnvironmentSettingsToJSON(BasicEnvironmentSettingJSONIntegrationTests.groovy:28)
I am able to use encodeAsJSON() successfully. I also have the same issue with as XML.
I think converters (as JSON syntax) will only work on domain objects and collections by default.
To convert arbitrary objects you should use the encodeAsJSON() converter, I believe. Or use an object marshaller, where you tell the converter how to deal with your object.
The docs aren't very clear on this though..
See:
http://grails.org/Converters+Reference (object marshalling section at bottom)
http://grails.org/doc/latest/ref/Plug-ins/codecs.html
But I note that http://grails.org/doc/latest/api/grails/converters/JSON.html#JSON%28java.lang.Object%29 says that the object converts POGOs.. Maybe it means if you have a marshaller?
I did find this reference too:
Notice that the ‘as’ operator is not overloaded for plain objects ...
Domain objects can use the ‘as’ operator to cast an object to JSON, the same as a collection. So unlike POGOs, where they must be massaged into a list or have encodeAsJSON explictly called ...
http://manbuildswebsite.com/2010/02/08/rendering-json-in-grails-part-2-plain-old-groovy-objects-and-domain-objects/
Which seems to describe the situation.
For non-Domain objects, we found that this would crop up when running tests... the solution for us was to use new JSON:
render new JSON( obj )
This would allow the test to work, and the code does the same thing (essentially)
Ran into a similar issue that broke unit test using grails 2.2.1 . At issue was a straight obj as JSON conversion attempt. But this was interpreted as type casting instead.
The workaround is to stuff your obj to be converted into a map like this [data:obj] as JSON