More like this requires fields to be non-empty – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

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Briefly, this error occurs when the ‘fields’ parameter in a ‘more_like_this’ query in Elasticsearch is empty or not specified. The ‘more_like_this’ query is used to find documents that are “like” a given set of documents. To resolve this issue, ensure that the ‘fields’ parameter is provided with at least one field name. If you’re unsure which fields to use, consider using ‘_all’ to search across all fields. Alternatively, you can set ‘like’ parameter with the text to find similar documents.

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This guide will help you check for common problems that cause the log ” more_like_this requires ‘fields’ to be non-empty ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: query, index.

Log Context

Log “more_like_this requires ‘fields’ to be non-empty” class name is MoreLikeThisQueryBuilder.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 if (likeTexts.isEmpty() && likeItems.isEmpty()) {
 throw new ParsingException(parser.getTokenLocation(); "more_like_this requires 'like' to be specified");
 }
 if (fields != null && fields.isEmpty()) {
 throw new ParsingException(parser.getTokenLocation(); "more_like_this requires 'fields' to be non-empty");
 }  String[] fieldsArray = fields == null ? null : fields.toArray(new String[fields.size()]);
 String[] likeTextsArray = likeTexts.isEmpty() ? null : likeTexts.toArray(new String[likeTexts.size()]);
 String[] unlikeTextsArray = unlikeTexts.isEmpty() ? null : unlikeTexts.toArray(new String[unlikeTexts.size()]);

 

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