How to add prefix and suffix when indexing - lucene

Question

How is it possible to add a suffix and prefix to an entity in Hibernate Search during indexing?
I need this to perform exact search.
E.g. if one is searching for "this is a test", then following entries are found:
* this is a test
* this is a test and ...
So I found the idea to add a prefix and suffix to the whole value during indexing, e.g.:
_____ this is a test _____
and if one is searching for "this is a test" and is enabling the checkbox for exact search, I'll change the search string to_
"_____ this is a test _____"
I created a FilterFactory for this, but with this one it adds the prefix and suffix to every term:
public boolean incrementToken() throws IOException {
if (!this.input.incrementToken()) {
return false;
} else {
String input = termAtt.toString();
// add "_____" at the beginning and ending of the phrase for exact match searching
input = "_____ " + input + " _____";
char[] newBuffer = input.toLowerCase().toCharArray();
termAtt.setEmpty();
termAtt.copyBuffer(newBuffer, 0, newBuffer.length);
return true;
}
}

Answer 1

This is not how you should do it.
What you need is that the string you index is considered a unique token. This way, you will only have results having the exact token.
To do so you need to define an analyzer based on the KeywordTokenizer.
#Entity
#AnalyzerDefs({
#AnalyzerDef(name = "keyword",
tokenizer = #TokenizerDef(factory = KeywordTokenizerFactory.class)
)
})
#Indexed
public class YourEntity {
#Fields({
#Field, // your default field with default analyzer if you need it
#Field(name = "propertyKeyword", analyzer = #Analyzer(definition = "keyword"))
})
private String property;
}
Then you should search on the propertyKeyword field. Note that the analyzer definition is global so you only need to declare the definition for one entity for it to be available for all your entities.
Take a look at the documentation about analyzers: http://docs.jboss.org/hibernate/stable/search/reference/en-US/html_single/#example-analyzer-def .
It's important to understand what an analyzer is for because usually the default one is not exactly the one you are looking for.