# How to check for existence of field in script
**URL:** https://discuss.elastic.co/t/how-to-check-for-existence-of-field-in-script/3815
**Category:** Elasticsearch
**Created:** [January 21, 2011, 5:54am UTC](https://discuss.elastic.co/t/how-to-check-for-existence-of-field-in-script/3815 "2011-01-21T05:54:22Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@dobe](https://discuss.elastic.co/u/dobe)
#### Post date: [January 21, 2011, 5:54am UTC](https://discuss.elastic.co/t/how-to-check-for-existence-of-field-in-script/3815/1 "2011-01-21T05:54:22Z")
hi all,
as already discussed on irc, i don't know how to check for the
existence of a field in a script filter. version 0.14.1 and 0.14.2
tried
note that this example is not the full implementation and i know that
this can be done without script it is just for demonstration.
so when i issue:
curl -XPUT $H/ft/Policy/1 -d '
{
"contract": "blah",
constraints:[
{
"regions": "reg1",
"applications": "app1"
},
{
"regions": "any",
"applications": "app2"
}
]
}
'
curl -XGET $H/ft/Policy/\_search?pretty=1 -d '
{
"query": {
"filtered" : {
"query" : {match\_all:{}},
"filter" : {
"script" : {
"script" : "\_source.contains\_key('x')"
,
"params" : {"a" : "app1", "r": "at"}
}
}
}
}
}
'
i get:
{
"took" : 87,
"\_shards" : {
"total" : 5,
"successful" : 4,
"failed" : 1,
"failures" : [ {
"index" : "ft",
"shard" : 2,
"reason" : "RemoteTransportException[[Harmonica][inet[/
192.168.34.135:9300]][search/phase/query]]; nested:
QueryPhaseExecutionException[[ft][2]:
query[filtered(ConstantScore(_:_))-
> ScriptFilter(\_source.contains\_key(x))],from[0],size[10]: Query Failed
> [Failed to execute main query]]; nested:
> PropertyAccessException[[Error: could not access: x; in class: null]
> \n[Near : {... Unknown ....}]\n ^\n[Line: 1, Column: 0]];
> "
> } ]
> },
> "hits" : {
> "total" : 0,
> "max\_score" : null,
> "hits" :
> }
> }
is there another way? imho "containsKey" sounds like it should return
a boolean
thx in advance, bernd
---
### Author:  [@kimchy](https://discuss.elastic.co/u/kimchy)
#### Post date: [January 23, 2011, 4:46pm UTC](https://discuss.elastic.co/t/how-to-check-for-existence-of-field-in-script/3815/2 "2011-01-23T16:46:54Z")
Does check for null works (the source is parsed into map of maps)? Try and use javascript, should make things simpler (and possibly faster). Note, accessing the \_source as part of a search request will mean loading the actual source json and parsing it, which can be expensive. You might consider using the doc['field\_name'] notation to access it by loading all values to memory. Then doc['field\_name'].empty will return true if the field has no data.
On Friday, January 21, 2011 at 7:54 AM, dobe wrote:
> hi all,
> as already discussed on irc, i don't know how to check for the
> existence of a field in a script filter. version 0.14.1 and 0.14.2
> tried
>
> note that this example is not the full implementation and i know that
> this can be done without script it is just for demonstration.
> so when i issue:
>
> curl -XPUT $H/ft/Policy/1 -d '
> {
> "contract": "blah",
> constraints:[
> {
> "regions": "reg1",
> "applications": "app1"
> },
> {
> "regions": "any",
> "applications": "app2"
> }
> ]
> }
> '
>
> curl -XGET $H/ft/Policy/\_search?pretty=1 -d '
> {
> "query": {
> "filtered" : {
> "query" : {match\_all:{}},
> "filter" : {
> "script" : {
> "script" : "\_source.contains\_key('x')"
> ,
> "params" : {"a" : "app1", "r": "at"}
> }
> }
> }
> }
> }
> '
>
> i get:
>
> {
> "took" : 87,
> "\_shards" : {
> "total" : 5,
> "successful" : 4,
> "failed" : 1,
> "failures" : [ {
> "index" : "ft",
> "shard" : 2,
> "reason" : "RemoteTransportException[[Harmonica][inet[/
> 192.168.34.135:9300]][search/phase/query]]; nested:
> QueryPhaseExecutionException[[ft][2]:
> query[filtered(ConstantScore(_:_))-
>
> > ScriptFilter(\_source.contains\_key(x))],from[0],size[10]: Query Failed
>
> [Failed to execute main query]]; nested:
> PropertyAccessException[[Error: could not access: x; in class: null]
> \n[Near : {... Unknown ....}]\n ^\n[Line: 1, Column: 0]];
> "
> } ]
> },
> "hits" : {
> "total" : 0,
> "max\_score" : null,
> "hits" :
> }
> }
>
> is there another way? imho "containsKey" sounds like it should return
> a boolean
> thx in advance, bernd
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 4:13am UTC](https://discuss.elastic.co/t/how-to-check-for-existence-of-field-in-script/3815/3 "2017-07-06T04:13:22Z")