What is escape property in query_string in elasticsearch

Question

I have a problem using wildcard in query_string in elasticsearch.I can not find documentation for the "escape" property in query_string when the value is "true" I got some results but when it is "false" the result is zero.

{
                    "query_string": {
                        "query": "*Serial\\+*",
                        "fields": [
                            "info.name^1.0"
                        ],
                        "type": "best_fields",
                        "allow_leading_wildcard": true,
                        "analyze_wildcard": true,
                        "escape": true,
                        "auto_generate_synonyms_phrase_query": true,
                        "fuzzy_transpositions": true,
                        "boost": 1.0
                    }
                }

can anybody explain the "escape" property?

Rule of thumb. If it's not documented, you should not use it. — Tomalak, Sep 12 '21 at 07:55
I opened an issue on github to add this flag to the docs, https://github.com/elastic/elasticsearch/issues/77604 — Ron Serruya, Sep 12 '21 at 08:54

score 3 · Answer 1 · answered Sep 12 '21 at 08:19

3

Weird that its not documented, but looking at the source code we can see:

Es query string source code

If "escape" is "true", the code calls org.apache.lucene.queryparser.classic.QueryParser.escape

On the query string, the function itself is documented as

Returns a String where those characters that QueryParser expects to be escaped are escaped by a preceding \.

So looks like this flag is just used to automatically escape characters for you, so you don't have to manually escape them

answered Sep 12 '21 at 08:19

Ron Serruya

3,988
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1

So this query (```"query": "*Serial\\+*" , "escape": false```) must has same result as (```"query": "*Serial+*" , "escape": true```) but their results aren't same. The first one returns zero doc and the second returns 30 docs. – saba safavi Sep 12 '21 at 08:35
@sabasafavi in the first one you don't escape `*`. Isn't that the difference? – Dalibor Filus Mar 16 '22 at 17:22

Tomalak · Answer 2 · 2021-09-12T08:55:25.983

Looking at the source code of QueryStringQueryBuilder.java (Github), we find

public class QueryStringQueryBuilder extends AbstractQueryBuilder<QueryStringQueryBuilder> {

    // ...

    public static final boolean DEFAULT_ESCAPE = false;

    // ...

    private boolean escape = DEFAULT_ESCAPE;

    // ...

    public QueryStringQueryBuilder(StreamInput in) throws IOException {
        // ...
        escape = in.readBoolean();
        // ...
    }

    // ...

    protected Query doToQuery(SearchExecutionContext context) throws IOException {
        String rewrittenQueryString = escape ? org.apache.lucene.queryparser.classic.QueryParser.escape(this.queryString) : queryString;
        // ...
    }
}

So it governs whether the query string is passed through the Lucene classic QueryParser's .escape() method, or not.

This parameter appears to be relevant if you want to use Lucene's query language instead of KQL. It might be a helper parameter for Kibana's web-based query interface, where you can switch between the two dialects.

Overall - if it's not documented, it's probably not meant for public use.

What is escape property in query_string in elasticsearch

2 Answers2