Class SortField

Stores information about how to sort documents by terms in an individual field. Fields must be indexed in order to sort by them.

Created: Feb 11, 2004 1:25:29 PM

@since lucene 1.4

Inheritance

System.Object

SortField

Namespace: Lucene.Net.Search

Assembly: Lucene.Net.dll

Syntax

public class SortField : object

Constructors

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SortField(String, FieldCache.IParser)

Creates a sort by terms in the given field, parsed to numeric values using a custom FieldCache.IParser.

Declaration

public SortField(string field, FieldCache.IParser parser)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by. Must not be `null`.
FieldCache.IParser	parser	Instance of a FieldCache.IParser, which must subclass one of the existing numeric parsers from IFieldCache. Sort type is inferred by testing which numeric parser the parser subclasses.

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SortField(String, FieldCache.IParser, Boolean)

Creates a sort, possibly in reverse, by terms in the given field, parsed to numeric values using a custom FieldCache.IParser.

Declaration

public SortField(string field, FieldCache.IParser parser, bool reverse)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by. Must not be `null`.
FieldCache.IParser	parser	Instance of a FieldCache.IParser, which must subclass one of the existing numeric parsers from IFieldCache. Sort type is inferred by testing which numeric parser the parser subclasses.
System.Boolean	reverse	`True` if natural order should be reversed.

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SortField(String, FieldComparerSource)

Creates a sort with a custom comparison function.

Declaration

public SortField(string field, FieldComparerSource comparer)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by; cannot be `null`.
FieldComparerSource	comparer	Returns a comparer for sorting hits.

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SortField(String, FieldComparerSource, Boolean)

Creates a sort, possibly in reverse, with a custom comparison function.

Declaration

public SortField(string field, FieldComparerSource comparer, bool reverse)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by; cannot be `null`.
FieldComparerSource	comparer	Returns a comparer for sorting hits.
System.Boolean	reverse	`True` if natural order should be reversed.

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SortField(String, SortFieldType)

Creates a sort by terms in the given field with the type of term values explicitly given.

Declaration

public SortField(string field, SortFieldType type)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by. Can be `null` if `type` is SCORE or DOC.
SortFieldType	type	Type of values in the terms.

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SortField(String, SortFieldType, Boolean)

Creates a sort, possibly in reverse, by terms in the given field with the type of term values explicitly given.

Declaration

public SortField(string field, SortFieldType type, bool reverse)

Parameters

Type	Name	Description
System.String	field	Name of field to sort by. Can be `null` if `type` is SCORE or DOC.
SortFieldType	type	Type of values in the terms.
System.Boolean	reverse	`True` if natural order should be reversed.

Fields

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FIELD_DOC

Represents sorting by document number (index order).

Declaration

public static readonly SortField FIELD_DOC

Field Value

Type	Description
SortField

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FIELD_SCORE

Represents sorting by document score (relevance).

Declaration

public static readonly SortField FIELD_SCORE

Field Value

Type	Description
SortField

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m_missingValue

Declaration

protected object m_missingValue

Field Value

Type	Description
System.Object

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STRING_FIRST

Pass this to MissingValue to have missing string values sort first.

Declaration

public static readonly object STRING_FIRST

Field Value

Type	Description
System.Object

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STRING_LAST

Pass this to MissingValue to have missing string values sort last.

Declaration

public static readonly object STRING_LAST

Field Value

Type	Description
System.Object

Properties

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BytesComparer

Declaration

public virtual IComparer<BytesRef> BytesComparer { get; set; }

Property Value

Type	Description
IComparer<BytesRef>

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ComparerSource

Returns the FieldComparerSource used for custom sorting.

Declaration

public virtual FieldComparerSource ComparerSource { get; }

Property Value

Type	Description
FieldComparerSource

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Field

Returns the name of the field. Could return null if the sort is by SCORE or DOC.

Declaration

public virtual string Field { get; }

Property Value

Type	Description
System.String	Name of field, possibly `null`.

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IsReverse

Returns whether the sort should be reversed.

Declaration

public virtual bool IsReverse { get; }

Property Value

Type	Description
System.Boolean	`True` if natural order should be reversed.

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MissingValue

Declaration

public virtual object MissingValue { get; set; }

Property Value

Type	Description
System.Object

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NeedsScores

Whether the relevance score is needed to sort documents.

Declaration

public virtual bool NeedsScores { get; }

Property Value

Type	Description
System.Boolean

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Parser

Returns the instance of a IFieldCache parser that fits to the given sort type. May return null if no parser was specified. Sorting is using the default parser then.

Declaration

public virtual FieldCache.IParser Parser { get; }

Property Value

Type	Description
FieldCache.IParser	An instance of a IFieldCache parser, or `null`.

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Type

Returns the type of contents in the field.

Declaration

public virtual SortFieldType Type { get; }

Property Value

Type	Description
SortFieldType	One of SCORE, DOC, STRING, INT32 or SINGLE.

Methods

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Equals(Object)

Returns true if o is equal to this. If a FieldComparerSource or FieldCache.IParser was provided, it must properly implement equals (unless a singleton is always used).

Declaration

public override bool Equals(object o)

Parameters

Type	Name	Description
System.Object	o

Returns

Type	Description
System.Boolean

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GetComparer(Int32, Int32)

Returns the FieldComparer to use for sorting.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Declaration

public virtual FieldComparer GetComparer(int numHits, int sortPos)

Parameters

Type	Name	Description
System.Int32	numHits	Number of top hits the queue will store
System.Int32	sortPos	Position of this SortField within Sort. The comparer is primary if sortPos==0, secondary if sortPos==1, etc. Some comparers can optimize themselves when they are the primary sort.

Returns

Type	Description
FieldComparer	FieldComparer to use when sorting

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GetHashCode()

Returns a hash code value for this object. If a FieldComparerSource or FieldCache.IParser was provided, it must properly implement GetHashCode() (unless a singleton is always used).

Declaration

public override int GetHashCode()

Returns

Type	Description
System.Int32

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Rewrite(IndexSearcher)

Rewrites this SortField, returning a new SortField if a change is made. Subclasses should override this define their rewriting behavior when this SortField is of type REWRITEABLE.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Declaration

public virtual SortField Rewrite(IndexSearcher searcher)

Parameters

Type	Name	Description
IndexSearcher	searcher	IndexSearcher to use during rewriting

Returns

Type	Description
SortField	New rewritten SortField, or `this` if nothing has changed.

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ToString()

Declaration

public override string ToString()

Returns

Type	Description
System.String