# Java.lang.NullPointerException: Cannot get property 'x' on null object - when running a groovy script

**URL:** <https://discuss.elastic.co/t/java-lang-nullpointerexception-cannot-get-property-x-on-null-object-when-running-a-groovy-script/47726>\
**Category:** Elasticsearch\
**Created:** [April 19, 2016, 12:29am UTC](https://discuss.elastic.co/t/java-lang-nullpointerexception-cannot-get-property-x-on-null-object-when-running-a-groovy-script/47726 "2016-04-19T00:29:29Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![tpraizler](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/tpraizler/32/46271_2.png) [@tpraizler](https://discuss.elastic.co/u/tpraizler)\
**Post date:** [April 19, 2016, 12:29am UTC](https://discuss.elastic.co/t/java-lang-nullpointerexception-cannot-get-property-x-on-null-object-when-running-a-groovy-script/47726/1 "2016-04-19T00:29:29Z")

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Hi,

I run a groovy script through the transport client:  
The script looks like this:

```
if (ctx._source.field.names == null) 
         ctx._source.field.names=newItems 
      else 
         ctx._source.field.names<< newItems; 
         ctx._source.field.names = ctx._source.field.names.flatten().unique()

```

My problem is that most of the times it works but sometimes I get the following error:

```
 Caused by: java.lang.IllegalArgumentException: failed to execute script 
   at org.elasticsearch.action.update.UpdateHelper.executeScript(UpdateHelper.java:256) ~[org.elasticsearch.elasticsearch-2.0.1.jar:2.0.1] 
   at org.elasticsearch.action.update.UpdateHelper.prepare(UpdateHelper.java:196) ~[org.elasticsearch.elasticsearch-2.0.1.jar:2.0.1] 
   at org.elasticsearch.action.update.UpdateHelper.prepare(UpdateHelper.java:79) ~[org.elasticsearch.elasticsearch-2.0.1.jar:2.0.1] 
   at org.elasticsearch.action.update.TransportUpdateAction.shardOperation(TransportUpdateAction.java:170) ~[org.elasticsearch.elasticsearch-2.0
   at org.elasticsearch.action.update.TransportUpdateAction$3$1.doRun(TransportUpdateAction.java:227) ~[org.elasticsearch.elasticsearch-2.0.1.
   at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37) ~[org.elasticsearch.elasticsearch-2.0.1.jar:2.0.1]
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) ~[na:1.8.0_74-cedar14] 
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) ~[na:1.8.0_74-cedar14] 
   at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_74-cedar14] 
 Caused by: org.elasticsearch.script.groovy.GroovyScriptExecutionException: failed to run inline script [if (ctx._source.field.names == null) 
     ctx._source.field.names=newItems 
  else 
     ctx._source.field.names<< newItems; 
     ctx._source.field.names = ctx._source.field.names.flatten().unique()] using lang [groovy] 
    at org.elasticsearch.script.groovy.GroovyScriptEngineService$GroovyScript.run(GroovyScriptEngineService.java:253) ~[org.elasticsearch.
    at org.elasticsearch.action.update.UpdateHelper.executeScript(UpdateHelper.java:251) ~[org.elasticsearch.elasticsearch-2.0.1.jar:2.0.1] 
    ... 8 common frames omitted 
  Caused by: java.lang.NullPointerException: Cannot get property 'names' on null object 
    at org.codehaus.groovy.runtime.NullObject.getProperty(NullObject.java:60) ~[org.codehaus.groovy.groovy-all-2.4.0.jar:2.4.0] 
    at org.codehaus.groovy.runtime.InvokerHelper.getProperty(InvokerHelper.java:172) ~[org.codehaus.groovy.groovy-all-2.4.0.jar:2.4.0] 
    at org.codehaus.groovy.runtime.callsite.NullCallSite.getProperty(NullCallSite.java:47) ~[org.codehaus.groovy.groovy-all-2.4.0.jar:2.4.0] 
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:296) ~[org.codehaus.groovy.groovy-all-2.4.0.
    at 889babff0826c95e16279a9fb1fd2eb97a63e642.run(889babff0826c95e16279a9fb1fd2eb97a63e642:1) ~[na:na] 
    at org.elasticsearch.script.groovy.GroovyScriptEngineService$GroovyScript.run(GroovyScriptEngineService.java:248) ~[org.elasticsearch.

```

I looked on the document the script fails on, and tried to manually run this script using curl, and it worked.  
So the document is not really the problem.

I am running this update for 38 documents, meaning it will run 38 times.  
The exception is thrown on a different document every time I try it this update from the beginning (meaning running it again on those 38 documents)

Not sure what I am missing here. any ideas?  
Thanks!

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 10:58pm UTC](https://discuss.elastic.co/t/java-lang-nullpointerexception-cannot-get-property-x-on-null-object-when-running-a-groovy-script/47726/2 "2017-07-05T22:58:19Z")

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