Adam Adam - 4 months ago 16
JSON Question

How to tell Grails to render JSONNull as null?

I have a JSON object returned from Groovy's HTTPBuilder. THE JSON contains some null values represented as JSONNull objects. The problem is that when I try to render the JSON back in a response, I get an error when it tries to render the JSONNull. I get a response that is only partially rendered. I want it to render as "null". How do I do this?

Code:

render(contentType: "text/json") {
listOfJSONObjectsThatIncludeJSONNulls
}


Error:

| Error 2013-09-17 11:33:56,965 [http-bio-8080-exec-4] ERROR errors.GrailsExceptionResolver - JSONException occurred when processing request: [GET] /my/action
Object is null. Stacktrace follows:
Message: Object is null
Line | Method
->> 69 | isEmpty in net.sf.json.JSONNull
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 199 | value in grails.converters.JSON
| 162 | convertAnother in ''
| 199 | value in ''
| 162 | convertAnother in ''
| 199 | value in ''
| 162 | convertAnother in ''
| 199 | value in ''
| 162 | convertAnother in ''
| 199 | value in ''
| 162 | convertAnother in ''
| 199 | value in ''
| 162 | convertAnother in ''
| 199 | value in ''
| 134 | render . . . . in ''
| 150 | render in ''
| 63 | doCall . . . . in myproject.MyController$_index_closure1_closure2_closure4$$EOHirVeS
| 477 | doRequest in groovyx.net.http.HTTPBuilder
| 417 | doRequest . . in ''
| 349 | request in ''
| 43 | doCall . . . . in myproject.MyController$_index_closure1$$EOHirVeS
| 477 | doRequest in groovyx.net.http.HTTPBuilder
| 268 | get . . . . . in ''
| 31 | index in myproject.MyController$$EOHirVeS
| 895 | runTask . . . in java.util.concurrent.ThreadPoolExecutor$Worker
| 918 | run in ''
^ 680 | run . . . . . in java.lang.Thread


Partially Rendered Output:

[{"keyWithNullValue":{"array":false,"class":"net.sf.json.JSONNull"

Answer

I used the following code to render JSONNull as an empty string.

grails.converters.JSON.registerObjectMarshaller(JSONNull, { return "" })
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