org.apache.lucene.search.function

Class CustomScoreQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.function.CustomScoreQuery

All Implemented Interfaces:

Serializable, Cloneable

public class CustomScoreQuery
extends Query

Query that sets document score as a programmatic function of several (sub) scores:

1. the score of its subQuery (any query)
2. (optional) the score of its ValueSourceQuery (or queries). For most simple/convenient use cases this query is likely to be a FieldScoreQuery

Subclasses can modify the computation by overriding getCustomScoreProvider(org.apache.lucene.index.IndexReader).

See Also:

Serialized Form

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor and Description
CustomScoreQuery(Query subQuery) Create a CustomScoreQuery over input subQuery.
CustomScoreQuery(Query subQuery, ValueSourceQuery... valSrcQueries) Create a CustomScoreQuery over input subQuery and a ValueSourceQuery.
CustomScoreQuery(Query subQuery, ValueSourceQuery valSrcQuery) Create a CustomScoreQuery over input subQuery and a ValueSourceQuery.

Method Summary

Methods

Modifier and Type	Method and Description
Object	clone() Returns a clone of this query.
Weight	createWeight(Searcher searcher) Expert: Constructs an appropriate Weight implementation for this query.
boolean	equals(Object o) Returns true if o is equal to this.
void	extractTerms(Set<Term> terms) Expert: adds all terms occurring in this query to the terms set.
protected CustomScoreProvider	getCustomScoreProvider(IndexReader reader) Returns a CustomScoreProvider that calculates the custom scores for the given IndexReader.
int	hashCode() Returns a hash code value for this object.
boolean	isStrict() Checks if this is strict custom scoring.
String	name() A short name of this query, used in toString(String).
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
void	setStrict(boolean strict) Set the strict mode of this query.
String	toString(String field) Prints a query to a string, with field assumed to be the default field and omitted.

Methods inherited from class org.apache.lucene.search.Query

combine, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CustomScoreQuery

public CustomScoreQuery(Query subQuery)

Create a CustomScoreQuery over input subQuery.

Parameters:

subQuery - the sub query whose scored is being customized. Must not be null.

CustomScoreQuery

public CustomScoreQuery(Query subQuery,
                ValueSourceQuery valSrcQuery)

Create a CustomScoreQuery over input subQuery and a ValueSourceQuery.

Parameters:

subQuery - the sub query whose score is being customized. Must not be null.

valSrcQuery - a value source query whose scores are used in the custom score computation. For most simple/convenient use case this would be a FieldScoreQuery. This parameter is optional - it can be null.

CustomScoreQuery

public CustomScoreQuery(Query subQuery,
                ValueSourceQuery... valSrcQueries)

Create a CustomScoreQuery over input subQuery and a ValueSourceQuery.

Parameters:

subQuery - the sub query whose score is being customized. Must not be null.

valSrcQueries - value source queries whose scores are used in the custom score computation. For most simple/convenient use case these would be FieldScoreQueries. This parameter is optional - it can be null or even an empty array.

Method Detail

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Description copied from class: Query

Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

Overrides:

rewrite in class Query

Throws:

IOException

extractTerms

public void extractTerms(Set<Term> terms)

Description copied from class: Query

Expert: adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten form.

Overrides:

extractTerms in class Query

clone

public Object clone()

Description copied from class: Query

Returns a clone of this query.

Overrides:

clone in class Query

toString

public String toString(String field)

Description copied from class: Query

Prints a query to a string, with field assumed to be the default field and omitted.

The representation used is one that is supposed to be readable by QueryParser. However, there are the following limitations:

• If the query was created by the parser, the printed representation may not be exactly what was parsed. For example, characters that need to be escaped will be represented without the required backslash.
• Some of the more complicated queries (e.g. span queries) don't have a representation that can be parsed by QueryParser.

Specified by:

toString in class Query

equals

public boolean equals(Object o)

Returns true if o is equal to this.

Overrides:

equals in class Query

hashCode

public int hashCode()

Returns a hash code value for this object.

Overrides:

hashCode in class Query

getCustomScoreProvider

protected CustomScoreProvider getCustomScoreProvider(IndexReader reader)
                                              throws IOException

Returns a CustomScoreProvider that calculates the custom scores for the given IndexReader. The default implementation returns a default implementation as specified in the docs of CustomScoreProvider.

Throws:

IOException

Since:

2.9.2

createWeight

public Weight createWeight(Searcher searcher)
                    throws IOException

Description copied from class: Query

Expert: Constructs an appropriate Weight implementation for this query.

Only implemented by primitive queries, which re-write to themselves.

Overrides:

createWeight in class Query

Throws:

IOException

isStrict

public boolean isStrict()

Checks if this is strict custom scoring. In strict custom scoring, the ValueSource part does not participate in weight normalization. This may be useful when one wants full control over how scores are modified, and does not care about normalizing by the ValueSource part. One particular case where this is useful if for testing this query.

Note: only has effect when the ValueSource part is not null.

setStrict

public void setStrict(boolean strict)

Set the strict mode of this query.

Parameters:

strict - The strict mode to set.

See Also:

isStrict()

name

public String name()

A short name of this query, used in toString(String).