org.apache.lucene.queryParser

Class MultiFieldQueryParser

Implemented Interfaces:
QueryParserConstants

public class MultiFieldQueryParser
extends QueryParser

A QueryParser which constructs queries to search multiple fields.
Version:
$Revision: 472959 $
Author:
Kelvin Tan, Daniel Naber

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.queryParser.QueryParser

QueryParser.Operator

Field Summary

Fields inherited from class org.apache.lucene.queryParser.QueryParser

AND_OPERATOR, OR_OPERATOR, jj_nt, lookingAhead, token, token_source

Fields inherited from interface org.apache.lucene.queryParser.QueryParserConstants

AND, Boost, CARAT, COLON, DEFAULT, EOF, FUZZY_SLOP, LPAREN, MINUS, NOT, NUMBER, OR, PLUS, PREFIXTERM, QUOTED, RANGEEX_END, RANGEEX_GOOP, RANGEEX_QUOTED, RANGEEX_START, RANGEEX_TO, RANGEIN_END, RANGEIN_GOOP, RANGEIN_QUOTED, RANGEIN_START, RANGEIN_TO, RPAREN, RangeEx, RangeIn, STAR, TERM, WILDTERM, _ESCAPED_CHAR, _NUM_CHAR, _TERM_CHAR, _TERM_START_CHAR, _WHITESPACE, tokenImage

Constructor Summary

MultiFieldQueryParser(String[] fields, Analyzer analyzer)
Creates a MultiFieldQueryParser.
MultiFieldQueryParser(String[] fields, Analyzer analyzer, Map boosts)
Creates a MultiFieldQueryParser.

Method Summary

protected Query
getFieldQuery(String field, String queryText)
protected Query
getFieldQuery(String field, String queryText, int slop)
Base implementation delegates to QueryParser.getFieldQuery(String,String).
protected Query
getFuzzyQuery(String field, String termStr, float minSimilarity)
Factory method for generating a query (similar to QueryParser.getWildcardQuery(String,String)).
protected Query
getPrefixQuery(String field, String termStr)
Factory method for generating a query (similar to QueryParser.getWildcardQuery(String,String)).
protected Query
getRangeQuery(String field, String part1, String part2, boolean inclusive)
protected Query
getWildcardQuery(String field, String termStr)
Factory method for generating a query.
static Query
parse(String query, String[] fields, BooleanClause.Occur[] flags, Analyzer analyzer)
Parses a query, searching on the fields specified.
static Query
parse(String[] queries, String[] fields, Analyzer analyzer)
Parses a query which searches on the fields specified.
static Query
parse(String[] queries, String[] fields, BooleanClause.Occur[] flags, Analyzer analyzer)
Parses a query, searching on the fields specified.

Methods inherited from class org.apache.lucene.queryParser.QueryParser

Clause, Conjunction, Modifiers, Query, ReInit, ReInit, Term, addClause, disable_tracing, enable_tracing, escape, generateParseException, getAllowLeadingWildcard, getAnalyzer, getBooleanQuery, getBooleanQuery, getDateResolution, getDefaultOperator, getField, getFieldQuery, getFieldQuery, getFuzzyMinSim, getFuzzyPrefixLength, getFuzzyQuery, getLocale, getLowercaseExpandedTerms, getNextToken, getPhraseSlop, getPrefixQuery, getRangeQuery, getToken, getUseOldRangeQuery, getWildcardQuery, main, parse, setAllowLeadingWildcard, setDateResolution, setDateResolution, setDefaultOperator, setFuzzyMinSim, setFuzzyPrefixLength, setLocale, setLowercaseExpandedTerms, setPhraseSlop, setUseOldRangeQuery

Constructor Details

MultiFieldQueryParser

public MultiFieldQueryParser(String[] fields,
                             Analyzer analyzer)
Creates a MultiFieldQueryParser.

It will, when parse(String query) is called, construct a query like this (assuming the query consists of two terms and you specify the two fields title and body): (title:term1 body:term1) (title:term2 body:term2)

When setDefaultOperator(AND_OPERATOR) is set, the result will be: +(title:term1 body:term1) +(title:term2 body:term2)

In other words, all the query's terms must appear, but it doesn't matter in what fields they appear.


MultiFieldQueryParser

public MultiFieldQueryParser(String[] fields,
                             Analyzer analyzer,
                             Map boosts)
Creates a MultiFieldQueryParser. Allows passing of a map with term to Boost, and the boost to apply to each term.

It will, when parse(String query) is called, construct a query like this (assuming the query consists of two terms and you specify the two fields title and body): (title:term1 body:term1) (title:term2 body:term2)

When setDefaultOperator(AND_OPERATOR) is set, the result will be: +(title:term1 body:term1) +(title:term2 body:term2)

When you pass a boost (title=>5 body=>10) you can get +(title:term1^5.0 body:term1^10.0) +(title:term2^5.0 body:term2^10.0)

In other words, all the query's terms must appear, but it doesn't matter in what fields they appear.

Method Details

getFieldQuery

protected Query getFieldQuery(String field,
                              String queryText)
            throws ParseException
Overrides:
getFieldQuery in interface QueryParser
Throws:
ParseException - throw in overridden method to disallow

getFieldQuery

protected Query getFieldQuery(String field,
                              String queryText,
                              int slop)
            throws ParseException
Base implementation delegates to QueryParser.getFieldQuery(String,String). This method may be overridden, for example, to return a SpanNearQuery instead of a PhraseQuery.
Overrides:
getFieldQuery in interface QueryParser
Throws:
ParseException - throw in overridden method to disallow

getFuzzyQuery

protected Query getFuzzyQuery(String field,
                              String termStr,
                              float minSimilarity)
            throws ParseException
Factory method for generating a query (similar to QueryParser.getWildcardQuery(String,String)). Called when parser parses an input term token that has the fuzzy suffix (~) appended.
Overrides:
getFuzzyQuery in interface QueryParser
Parameters:
field - Name of the field query will use.
termStr - Term token to use for building term for the query
Returns:
Resulting Query built for the term
Throws:
ParseException - throw in overridden method to disallow

getPrefixQuery

protected Query getPrefixQuery(String field,
                               String termStr)
            throws ParseException
Factory method for generating a query (similar to QueryParser.getWildcardQuery(String,String)). Called when parser parses an input term token that uses prefix notation; that is, contains a single '*' wildcard character as its last character. Since this is a special case of generic wildcard term, and such a query can be optimized easily, this usually results in a different query object.

Depending on settings, a prefix term may be lower-cased automatically. It will not go through the default Analyzer, however, since normal Analyzers are unlikely to work properly with wildcard templates.

Can be overridden by extending classes, to provide custom handling for wild card queries, which may be necessary due to missing analyzer calls.

Overrides:
getPrefixQuery in interface QueryParser
Parameters:
field - Name of the field query will use.
termStr - Term token to use for building term for the query (without trailing '*' character!)
Returns:
Resulting Query built for the term
Throws:
ParseException - throw in overridden method to disallow

getRangeQuery

protected Query getRangeQuery(String field,
                              String part1,
                              String part2,
                              boolean inclusive)
            throws ParseException
Overrides:
getRangeQuery in interface QueryParser
Throws:
ParseException - throw in overridden method to disallow

getWildcardQuery

protected Query getWildcardQuery(String field,
                                 String termStr)
            throws ParseException
Factory method for generating a query. Called when parser parses an input term token that contains one or more wildcard characters (? and *), but is not a prefix term token (one that has just a single * character at the end)

Depending on settings, prefix term may be lower-cased automatically. It will not go through the default Analyzer, however, since normal Analyzers are unlikely to work properly with wildcard templates.

Can be overridden by extending classes, to provide custom handling for wildcard queries, which may be necessary due to missing analyzer calls.

Overrides:
getWildcardQuery in interface QueryParser
Parameters:
field - Name of the field query will use.
termStr - Term token that contains one or more wild card characters (? or *), but is not simple prefix term
Returns:
Resulting Query built for the term
Throws:
ParseException - throw in overridden method to disallow

parse

public static Query parse(String query,
                          String[] fields,
                          BooleanClause.Occur[] flags,
                          Analyzer analyzer)
            throws ParseException
Parses a query, searching on the fields specified. Use this if you need to specify certain fields as required, and others as prohibited.

 Usage:
 
 String[] fields = {"filename", "contents", "description"};
 BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
                BooleanClause.Occur.MUST,
                BooleanClause.Occur.MUST_NOT};
 MultiFieldQueryParser.parse("query", fields, flags, analyzer);
 
 

The code above would construct a query:

 
 (filename:query) +(contents:query) -(description:query)
 
 
Parameters:
query - Query string to parse
fields - Fields to search on
flags - Flags describing the fields
analyzer - Analyzer to use
Throws:
ParseException - if query parsing fails

parse

public static Query parse(String[] queries,
                          String[] fields,
                          Analyzer analyzer)
            throws ParseException
Parses a query which searches on the fields specified.

If x fields are specified, this effectively constructs:

 
 (field1:query1) (field2:query2) (field3:query3)...(fieldx:queryx)
 
 
Parameters:
queries - Queries strings to parse
fields - Fields to search on
analyzer - Analyzer to use
Throws:
ParseException - if query parsing fails

parse

public static Query parse(String[] queries,
                          String[] fields,
                          BooleanClause.Occur[] flags,
                          Analyzer analyzer)
            throws ParseException
Parses a query, searching on the fields specified. Use this if you need to specify certain fields as required, and others as prohibited.

 Usage:
 
 String[] query = {"query1", "query2", "query3"};
 String[] fields = {"filename", "contents", "description"};
 BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
                BooleanClause.Occur.MUST,
                BooleanClause.Occur.MUST_NOT};
 MultiFieldQueryParser.parse(query, fields, flags, analyzer);
 
 

The code above would construct a query:

 
 (filename:query1) +(contents:query2) -(description:query3)
 
 
Parameters:
queries - Queries string to parse
fields - Fields to search on
flags - Flags describing the fields
analyzer - Analyzer to use
Throws:
ParseException - if query parsing fails

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