Elasticsearch - Create field using script if doesn't exist

Question

Is there a way to dynamically add fields using scripts? I am running a script that checks whether a field exists. If not then creates it.

I'm trying out:

script: 'if (ctx._source.attending == null) { ctx._source.attending = { events: newField } } else if (ctx._source.attending.events == null) { ctx._source.attending.events = newField } else { ctx._source.attending.events += newField }'

Except unless I have a field in my _source explicitly named attending in my case, I get:

[Error: ElasticsearchIllegalArgumentException[failed to execute script];
nested: PropertyAccessException[
    [Error: could not access: attending; in class: java.util.LinkedHashMap]

Olly Cruickshank · Accepted Answer · 2014-11-17 20:41:55Z

17

To check whether a field exists use the ctx._source.containsKey function, e.g.:

curl -XPOST "http://localhost:9200/myindex/message/1/_update" -d'
{
   "script": "if (!ctx._source.containsKey(\"attending\")) { ctx._source.attending = newField }",
   "params" : {"newField" : "blue" },
   "myfield": "data"
}'

answered Nov 17, 2014 at 20:41

Olly Cruickshank

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2 Comments

Maruf Over a year ago

Thanks will test this out when I get a chance. Is there a site with all the methods like contains and containsKey? If I knew where to look I would tried them.

Olly Cruickshank Over a year ago

I'm not aware of any single resource - my info comes from a variety of forums. When I ran into this problem, I eventually decided to store the fields in a separate child document - this seems more robust and simpler.

jhilden · Accepted Answer · 2014-11-17 22:27:26Z

0

I would consider if it's really necessary to see if the field exists at all. Just apply the new mapping to ES and it will add it if it's required and do nothing if it already exists.

Our system re-applies the mappings on every application startup.

answered Nov 17, 2014 at 22:27

jhilden

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2 Comments

Maruf Over a year ago

The field exists in the mapping, but it would throw the error regardless

Olly Cruickshank Over a year ago

If it was a simple field - then yes, upsert would work. However this looks like an array of values, the script needs to add to the array if it exists or create it if it doesn't.

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