Class FieldMaskingSpanQuery
- java.lang.Object
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- org.apache.lucene.search.Query
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- org.apache.lucene.search.spans.SpanQuery
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- org.apache.lucene.search.spans.FieldMaskingSpanQuery
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public final class FieldMaskingSpanQuery extends SpanQuery
Wrapper to allow
SpanQuery
objects participate in composite single-field SpanQueries by 'lying' about their search field. That is, the masked SpanQuery will function as normal, butSpanQuery.getField()
simply hands back the value supplied in this class's constructor.This can be used to support Queries like
SpanNearQuery
orSpanOrQuery
across different fields, which is not ordinarily permitted.This can be useful for denormalized relational data: for example, when indexing a document with conceptually many 'children':
teacherid: 1 studentfirstname: james studentsurname: jones teacherid: 2 studenfirstname: james studentsurname: smith studentfirstname: sally studentsurname: jones
a SpanNearQuery with a slop of 0 can be applied across two
SpanTermQuery
objects as follows:SpanQuery q1 = new SpanTermQuery(new Term("studentfirstname", "james")); SpanQuery q2 = new SpanTermQuery(new Term("studentsurname", "jones")); SpanQuery q2m = new FieldMaskingSpanQuery(q2, "studentfirstname"); Query q = new SpanNearQuery(new SpanQuery[]{q1, q2m}, -1, false);
to search for 'studentfirstname:james studentsurname:jones' and find teacherid 1 without matching teacherid 2 (which has a 'james' in position 0 and 'jones' in position 1).Note: as
getField()
returns the masked field, scoring will be done using the Similarity and collection statistics of the field name supplied, but with the term statistics of the real field. This may lead to exceptions, poor performance, and unexpected scoring behaviour.
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Constructor Summary
Constructors Constructor Description FieldMaskingSpanQuery(SpanQuery maskedQuery, String maskedField)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description SpanWeight
createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)
Expert: Constructs an appropriate Weight implementation for this query.boolean
equals(Object other)
Override and implement query instance equivalence properly in a subclass.String
getField()
Returns the name of the field matched by this query.SpanQuery
getMaskedQuery()
int
hashCode()
Override and implement query hash code properly in a subclass.Query
rewrite(IndexReader reader)
Expert: called to re-write queries into primitive queries.String
toString(String field)
Prints a query to a string, withfield
assumed to be the default field and omitted.void
visit(QueryVisitor visitor)
Recurse through the query tree, visiting any child queries-
Methods inherited from class org.apache.lucene.search.spans.SpanQuery
getTermStates, getTermStates
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Methods inherited from class org.apache.lucene.search.Query
classHash, sameClassAs, toString
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Method Detail
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getField
public String getField()
Description copied from class:SpanQuery
Returns the name of the field matched by this query.
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getMaskedQuery
public SpanQuery getMaskedQuery()
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createWeight
public SpanWeight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) 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.
- Specified by:
createWeight
in classSpanQuery
scoreMode
- How the produced scorers will be consumed.boost
- The boost that is propagated by the parent queries.- Throws:
IOException
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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 classQuery
- Throws:
IOException
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visit
public void visit(QueryVisitor visitor)
Description copied from class:Query
Recurse through the query tree, visiting any child queries
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toString
public String toString(String field)
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted.
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equals
public boolean equals(Object other)
Description copied from class:Query
Override and implement query instance equivalence properly in a subclass. This is required so thatQueryCache
works properly. Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.- Specified by:
equals
in classQuery
- See Also:
Query.sameClassAs(Object)
,Query.classHash()
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hashCode
public int hashCode()
Description copied from class:Query
Override and implement query hash code properly in a subclass. This is required so thatQueryCache
works properly.- Specified by:
hashCode
in classQuery
- See Also:
Query.equals(Object)
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