[GitHub] [lucene-solr] bruno-roustant commented on a change in pull request #1819: SOLR-14782: Document how to unescape for the QueryElevationComponent.

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bruno-roustant commented on a change in pull request #1819:
URL: https://github.com/apache/lucene-solr/pull/1819#discussion_r482110458



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File path: solr/solr-ref-guide/src/the-query-elevation-component.adoc
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@@ -61,7 +61,18 @@ Optionally, in the Query Elevation Component configuration you can also specify
 The Query Elevation Search Component takes the following parameters:
 
 `queryFieldType`::
-Specifies which fieldType should be used to analyze the incoming text. For example, it may be appropriate to use a fieldType with a LowerCaseFilter.
+Specifies which fieldType should be used to analyze the incoming text. For example, it may be appropriate to use a fieldType with a LowerCaseFilter. Other example, if you need to unescape backslash-escaped queries, then you can define the fieldType to preprocess with a PatternReplaceCharFilter. Here is the corresponding example of fieldType (traditionally in `schema.xml`):
+
+[source,xml]
+----
+<fieldType name="unescapelowercase" class="solr.TextField">
+  <analyzer>
+    <charFilter class="solr.PatternReplaceCharFilterFactory" pattern="\\(.)" replacement="$1"/>

Review comment:
       Indeed, but do we want to go into this level of detail?
   The Lucene StandardQueryParser uses EscapeQuerySyntaxImpl.discardEscapeChar() which unescape everything without distinction except it detects unicode \uxxxx and converts it.
   I suggest that we give a basic example of unescaping every backslash. If the user wants more sophisticated logic, then she will design the right pattern or the custom CharFilter.




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