Interface SortBy
- All Known Implementing Classes:
SortByImpl
Having SortBy at the Filter level is an interesting undertaking of Filter 1.1 support. Why you ask? It is at the Same level as Filter, it is not *used* by Filter itself. The services that make use of Filter, such as WFS are starting to make use of SortBy in the same breath.
Where is SortBy used:
- WFS 1.1 Query
- CSW 2.0.1 AbstractQuery
What this means is that the GeoTools Query will make use of this construct. As for sorting the result of an expression (where an expression matches more then one element), we will splice it in to AttributeExpression as an optional parameter. Note function is defined to return a single value (so we don't need to worry there).
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Field Summary
Fields -
Method Summary
Modifier and TypeMethodDescriptionIndicate property to sort by, specification is limited to PropertyName.The the sort order - one ofASCENDING
orDESCENDING
.
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Field Details
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UNSORTED
Used to indicate lack of a sorting order.This is the default value for used when setting up a Query.
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NATURAL_ORDER
Used to indicate "natural" sorting order, usually according FID (hopefully based on Key attribtues).This is the order that is most likely to be available in optimzied form, if an Attribute is marked as "key" an optimized ordering should be considered avaialble.
Non optimized orderings are will at the very least require as pass through the data to bring it into memory, you can assume somekind of TreeSet would be used. Where the nodes in the tree would indicate a list of FeatureIds assoicated with the node, in the order encountered.
This is a "NullObject".
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REVERSE_ORDER
Indicate the reverse order, usually assoicated with "Fid".This is a "NullObject".
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Method Details
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getPropertyName
PropertyName getPropertyName()Indicate property to sort by, specification is limited to PropertyName.Not sure if this is allowed to be a xPath expression?
- It would be consist with our use in GeoTools
- It would not seem to agree with the short hand notation used by WFS1.1 (ie. "year A, month A, day A" )
- Returns:
- Name of property to sort by.
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getSortOrder
SortOrder getSortOrder()The the sort order - one ofASCENDING
orDESCENDING
.
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