# Checking for missing date fields in painless script **URL:** \ **Category:** Elasticsearch\ **Tags:** painless\ **Created:** [December 20, 2018, 6:14pm UTC](https://discuss.elastic.co/t/checking-for-missing-date-fields-in-painless-script/161743 "2018-12-20T18:14:35Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![vicpav](https://avatars.discourse-cdn.com/v4/letter/v/9de053/32.png) [@vicpav](https://discuss.elastic.co/u/vicpav)\ **Post date:** [December 20, 2018, 6:14pm UTC](https://discuss.elastic.co/t/checking-for-missing-date-fields-in-painless-script/161743/1 "2018-12-20T18:14:35Z")
Elasticsearch 6.4.3 I have an index file synced from PostgreSQL with the original timestamp `created_at` configured as `date` type. At some later moment, a new timestamp `event_timestamp` (also `date` type) has been introduces to the documents and I want to switch to use that as the index primary timestamp in Kibana. Now, I am trying to update the index in place by making the `_update_by_query` query such that would fill `event_timestamp` with the value of `created_at` everywhere where it is missing. But I fail to construct the condition for missing **date** value in painless script. When I try running ``` POST dev-order-events-000001/_update_by_query { "script": { "lang": "painless", "source": """ if (ctx._source.event_timestamp == 0) { ctx._source.event_timestamp = ctx._source.created_at; } else { ctx.op = "noop"; } """ } } ``` the script does not find any match. Checking for `ctx._source.event_timestamp.size() == 0` results in the error ``` { "error": { "root_cause": [ { "type": "script_exception", "reason": "runtime error", "script_stack": [ "if (ctx._source.event_timestamp.size() == 0) {\n ", " ^---- HERE" ], "script": " if (ctx._source.event_timestamp.size() == 0) {\n ctx._source.event_timestamp = ctx._spource.created_at;\n } else { \n ctx.op = \"noop\";\n }", "lang": "painless" } ], "type": "script_exception", "reason": "runtime error", "script_stack": [ "if (ctx._source.event_timestamp.size() == 0) {\n ", " ^---- HERE" ], "script": " if (ctx._source.event_timestamp.size() == 0) {\n ctx._source.event_timestamp = ctx._spource.created_at;\n } else { \n ctx.op = \"noop\";\n }", "lang": "painless", "caused_by": { "type": "illegal_argument_exception", "reason": "Unable to find dynamic method [size] with [0] arguments for class [java.lang.Long]." } }, "status": 500 } ``` Checking for `doc['event_timestamp'].size() == 0` also does not go through: ``` { "error": { "root_cause": [ { "type": "script_exception", "reason": "runtime error", "script_stack": [ "if (doc['event_timestamp'].size() == 0) {\n ", " ^---- HERE" ], "script": " if (doc['event_timestamp'].size() == 0) {\n ctx._source.event_timestamp = ctx._spource.created_at;\n } else { \n ctx.op = \"noop\";\n }", "lang": "painless" } ], "type": "script_exception", "reason": "runtime error", "script_stack": [ "if (doc['event_timestamp'].size() == 0) {\n ", " ^---- HERE" ], "script": " if (doc['event_timestamp'].size() == 0) {\n ctx._source.event_timestamp = ctx._spource.created_at;\n } else { \n ctx.op = \"noop\";\n }", "lang": "painless", "caused_by": { "type": "null_pointer_exception", "reason": null } }, "status": 500 } ``` Description of the missing `date` field in [6.4/painless-examples.html](https://www.elastic.co/guide/en/elasticsearch/painless/6.4/painless-examples.html) is very "cryptic" without specifying returned value. > If you request the value from a field `field` that isn’t in the document, `doc['field'].value` for this document returns: > ... > epoch date if a `field` has a date datatype And the "officially recommended" solution tom check for missing values mentioned there is > To check if a document is missing a value, you can call `doc['field'].size() == 0` . which I found to be not working. 😞 What am I possibly doing wrong? ---
**Author:** ![rjernst](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rjernst/32/6363_2.png) [@rjernst](https://discuss.elastic.co/u/rjernst)\ **Post date:** [December 20, 2018, 7:28pm UTC](https://discuss.elastic.co/t/checking-for-missing-date-fields-in-painless-script/161743/2 "2018-12-20T19:28:47Z")
Are you sure `event_timestamp` doesn't exist as a field for any documents? To check if the field exists in source, you would use containsKey: ```auto if (ctx._source.containsKey('event_timestamp')) { // event timestamp exists } else { // even timestamp does not exist } ``` Regarding `doc`, that is special variable only available in some script contexts. Unfortunately, update scripts are not one of them. ---
**Author:** ![vicpav](https://avatars.discourse-cdn.com/v4/letter/v/9de053/32.png) [@vicpav](https://discuss.elastic.co/u/vicpav)\ **Post date:** [December 20, 2018, 7:37pm UTC](https://discuss.elastic.co/t/checking-for-missing-date-fields-in-painless-script/161743/3 "2018-12-20T19:37:00Z")
Thank you so much, @rjernst! It is `containsKey` method that I was looking for. After that, the script ``` POST dev-order-events-000001/_update_by_query { "script": { "lang": "painless", "source": """ if (ctx._source.containsKey('event_timestamp')) { ctx.op = "noop"; } else { ctx._source.event_timestamp = ctx._source.created_at; } """ } } ``` worked like a charm. πŸ‘ ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [January 17, 2019, 7:37pm UTC](https://discuss.elastic.co/t/checking-for-missing-date-fields-in-painless-script/161743/4 "2019-01-17T19:37:19Z")
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