Package org.apache.lucene.queries.function

# Class FunctionScoreQuery

java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.queries.function.FunctionScoreQuery

public final class FunctionScoreQuery extends Query
A query that wraps another query, and uses a DoubleValuesSource to replace or modify the wrapped query's score

If the DoubleValuesSource doesn't return a value for a particular document, then that document will be given a score of 0.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `FunctionScoreQuery(Query in, DoubleValuesSource source)`
  Create a new FunctionScoreQuery

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static FunctionScoreQuery`
  `boostByQuery(Query in, Query boostMatch, float boostValue)`
  Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by a boost factor if the document being scored also matches a separate boosting query.
  `static FunctionScoreQuery`
  `boostByValue(Query in, DoubleValuesSource boost)`
  Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by the value of a DoubleValuesSource.
  `Weight`
  `createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)`
  `boolean`
  `equals(Object o)`
  `DoubleValuesSource`
  `getSource()`
  `Query`
  `getWrappedQuery()`
  `int`
  `hashCode()`
  `Query`
  `rewrite(IndexSearcher indexSearcher)`
  `String`
  `toString(String field)`
  `void`
  `visit(QueryVisitor visitor)`

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

  `classHash, sameClassAs, toString`

  ### Methods inherited from class java.lang.Object

  `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### FunctionScoreQuery

    public FunctionScoreQuery(Query in, DoubleValuesSource source)
    Create a new FunctionScoreQuery
    Parameters:
      `in` - the query to wrap
      `source` - a source of scores

- ## Method Details

  - ### getWrappedQuery

    public Query getWrappedQuery()
    Returns:
      the wrapped Query

  - ### getSource

    public DoubleValuesSource getSource()
    Returns:
      the underlying value source

  - ### boostByValue

    public static FunctionScoreQuery boostByValue(Query in, DoubleValuesSource boost)
    Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by the value of a DoubleValuesSource.

    If the source has no value for a particular document, the score for that document is preserved as-is.

    Parameters:
      `in` - the query to boost
      `boost` - a `DoubleValuesSource` containing the boost values

  - ### boostByQuery

    public static FunctionScoreQuery boostByQuery(Query in, Query boostMatch, float boostValue)
    Returns a FunctionScoreQuery where the scores of a wrapped query are multiplied by a boost factor if the document being scored also matches a separate boosting query.

    Documents that do not match the boosting query have their scores preserved.

    This may be used to 'demote' documents that match the boosting query, by passing in a boostValue between 0 and 1.

    Parameters:
      `in` - the query to boost
      `boostMatch` - the boosting query
      `boostValue` - the amount to boost documents which match the boosting query

  - ### createWeight

    public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException
    Overrides:
      `createWeight` in class `Query`
    Throws:
      `IOException`

  - ### rewrite

    public Query rewrite(IndexSearcher indexSearcher) throws IOException
    Overrides:
      `rewrite` in class `Query`
    Throws:
      `IOException`

  - ### visit

    public void visit(QueryVisitor visitor)
    Specified by:
      `visit` in class `Query`

  - ### toString

    public String toString(String field)
    Specified by:
      `toString` in class `Query`

  - ### equals

    public boolean equals(Object o)
    Specified by:
      `equals` in class `Query`

  - ### hashCode

    public int hashCode()
    Specified by:
      `hashCode` in class `Query`