# What are the allowed characters in field names? **URL:** \ **Category:** Elasticsearch\ **Created:** [October 18, 2011, 7:39am UTC](https://discuss.elastic.co/t/what-are-the-allowed-characters-in-field-names/5621 "2011-10-18T07:39:17Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![datadev](https://avatars.discourse-cdn.com/v4/letter/d/ea5d25/32.png) [@datadev](https://discuss.elastic.co/u/datadev)\ **Post date:** [October 18, 2011, 7:39am UTC](https://discuss.elastic.co/t/what-are-the-allowed-characters-in-field-names/5621/1 "2011-10-18T07:39:17Z")
What are the allowed characters in field names? Specifically, are hyphens allowed in field names? I currently have a term facet that has a 'script' attribute being "term + 'aaa' + \_source.foo-bar" and I am getting the following exception: Query Failed [Failed to execute main query]]; nested: PropertyAccessException[[Error: could not access: [bar; in class: org.elasticsearch.search.lookup.SourceLookup] Based on this exception, it seems that ES is treating the hyphen as a delimiter between 2 fields? If hyphens are not allowed in field names, is there definitive documentation on what characters (ideally in a regex if there are also rules about acceptable first characters, etc...) are allowed in field names? Thanks. ---
**Author:** ![datadev](https://avatars.discourse-cdn.com/v4/letter/d/ea5d25/32.png) [@datadev](https://discuss.elastic.co/u/datadev)\ **Post date:** [October 18, 2011, 7:49am UTC](https://discuss.elastic.co/t/what-are-the-allowed-characters-in-field-names/5621/2 "2011-10-18T07:49:00Z")
BTW, here is a link regarding field names in solr for reference: [https://issues.apache.org/jira/browse/SOLR-2606](https://issues.apache.org/jira/browse/SOLR-2606) On Oct 18, 3:39 am, datadev [n...@adinfocenter.com](mailto:n...@adinfocenter.com) wrote: > What are the allowed characters in field names? Specifically, are > hyphens allowed in field names? I currently have a term facet that has > a 'script' attribute being "term + 'aaa' + \_source.foo-bar" and I am > getting the following exception: Query Failed [Failed to execute main > query]]; nested: PropertyAccessException[[Error: could not access: > [bar; in class: org.elasticsearch.search.lookup.SourceLookup] > > Based on this exception, it seems that ES is treating the hyphen as a > delimiter between 2 fields? > > If hyphens are not allowed in field names, is there definitive > documentation on what characters (ideally in a regex if there are also > rules about acceptable first characters, etc...) are allowed in field > names? > > Thanks. ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [October 18, 2011, 5:45pm UTC](https://discuss.elastic.co/t/what-are-the-allowed-characters-in-field-names/5621/3 "2011-10-18T17:45:59Z")
There isn't really a limit on what can be in a field name. In your case, the script is actually a script (by default, mvel). Since \_source is actually treated as a Map lookup, you can do \_source['foo-bar']. On Tue, Oct 18, 2011 at 9:39 AM, datadev [nji@adinfocenter.com](mailto:nji@adinfocenter.com) wrote: > What are the allowed characters in field names? Specifically, are > hyphens allowed in field names? I currently have a term facet that has > a 'script' attribute being "term + 'aaa' + \_source.foo-bar" and I am > getting the following exception: Query Failed [Failed to execute main > query]]; nested: PropertyAccessException[[Error: could not access: > [bar; in class: org.elasticsearch.search.lookup.SourceLookup] > > Based on this exception, it seems that ES is treating the hyphen as a > delimiter between 2 fields? > > If hyphens are not allowed in field names, is there definitive > documentation on what characters (ideally in a regex if there are also > rules about acceptable first characters, etc...) are allowed in field > names? > > Thanks. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:51am UTC](https://discuss.elastic.co/t/what-are-the-allowed-characters-in-field-names/5621/4 "2017-07-06T03:51:32Z")