Class Query
- Object
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- Query
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- Direct Known Subclasses:
JoiningQuery
public class Query extends Object
Encapsulates a request for data, typically as:
The query class is based on the Web Feature Server specification and offers a few interesting capabilities such as the ability to sort results and use a filter (similar to the WHERE clause in SQL).Query query = ... myFeatureSource.getFeatures(query);
Additional capabilities:
- setMaxFeatures(int) and setStartIndex(Integer) can be used implement 'paging' through the data source's content. This is useful if, for example, the FeatureSource has an upper limit on the number of features it can return in a single request or you are working with limited memory.
- setHandle(String) can be used to give the query a mnemonic name which will appear in error reporing and logs.
- setCoordinateSystem(CoordinateReferenceSystem) is used to to specify the coordinate system that retrieved features will be "forced" into. This is often used to correct a feature source when the application and the data format have different ideas about the coordinate system (for example, the "axis order" issue).
- setCoordinateSystemReproject(CoordinateReferenceSystem) is used to ask for the retrieved features to be reproejcted.
- setHints(org.geotools.util.factory.Hints) is used to specify venfor specific capabilities provided by a feature source implementation.
The Query class supports the concepts of joins in that a query can result in a join of the feature type to other feature types in the same datastore. For example, the following would be a spatial join that selected the country that contain a particular city.
Example:Query query = new Query("countries"); Join join = new Join("cities", CQL.toFilter("CONTAINS(geometry, b.geometry)")); join.setAlias("b"); join.setFilter(CQL.toFilter("CITY_NAME = 'Canmore'")) query.getJoins().add(join);
Filter filter = CQL.toFilter("NAME like '%land'"); Query query = new Query( "countries", filter ); FeatureCollection features = featureSource.getFeatures( query );
- Author:
- Chris Holmes
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Field Summary
Fields Modifier and Type Field Description protected String
alias
The optional alias for type namestatic Query
ALL
Implements a query that will fetch all features from a datasource.static String[]
ALL_NAMES
A constant (valuenull
) that can be used with setPropertyNames(String[]) to indicate that all properties are to be retrieved.static List<PropertyName>
ALL_PROPERTIES
A constant (valuenull
) that can be used with #setProperties(Collection) to indicate that all properties are to be retrieved. protected CoordinateReferenceSystem
coordinateSystem
Coordinate System associated with this queryprotected CoordinateReferenceSystem
coordinateSystemReproject
Reprojection associated associated with this querystatic int
DEFAULT_MAX
So getMaxFeatures does not return null we use a very large number.static Query
FIDS
Implements a query that will fetch all the FeatureIDs from a datasource.protected Filter
filter
The filter to constrain the request.protected String
handle
The handle associated with this query.protected Hints
hints
The hints to be used during query executionstatic Hints.Key
INCLUDE_MANDATORY_PROPS
When specifying properties to select, setting this hint flag true tells the datastore to include mandatory properties (i.e. properties with minOccurs >= 1) in the end result, irrespective of whether they are not included in the list of properties.protected List<Join>
joins
join clauses for this queryprotected int
maxFeatures
The maximum numbers of features to fetchprotected URI
namespace
The namespace to getstatic String[]
NO_NAMES
A constant (empty String array) that can be used with setPropertyNames(String[]) to indicate that no properties are to be retrieved.static URI
NO_NAMESPACE
Constant (actually null) used to represent no namespace restrictions on the returned result, should be considered ANY_URIstatic List<PropertyName>
NO_PROPERTIES
A constant (empty String array) that can be used with #setProperties(Collection) to indicate that no properties are to be retrieved. protected List<PropertyName>
properties
The properties to fetchprotected SortBy[]
sortBy
Sorting for the queryprotected Integer
startIndex
The index of the first feature to processprotected String
typeName
The typeName to getprotected String
version
The version according to WFS 1.0 and 1.1 specs
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Constructor Summary
Constructors Constructor Description Query()
Default constructor.Query(String typeName)
Constructor.Query(String typeName, URI namespace, Filter filter, int maxFeatures, String[] propNames, String handle)
Constructor.Query(String typeName, URI namespace, Filter filter, int maxFeatures, List<PropertyName> properties, String handle)
Constructor.Query(String typeName, Filter filter)
Constructor.Query(String typeName, Filter filter, int maxFeatures, String[] propNames, String handle)
Constructor.Query(String typeName, Filter filter, int maxFeatures, List<PropertyName> properties, String handle)
Constructor.Query(String typeName, Filter filter, String... properties)
Constructor.Query(String typeName, Filter filter, List<PropertyName> properties)
Constructor.Query(Query query)
Copy contructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
equals(Object obj)
Equality based on all query parameters other than the handle.String
getAlias()
An alias substitutable forgetTypeName()
.CoordinateReferenceSystem
getCoordinateSystem()
Get the coordinate system to use as an override for features retrieved by this Query.CoordinateReferenceSystem
getCoordinateSystemReproject()
If reprojection has been requested, this returns the coordinate system that features retrieved by this Query will be reprojected into.Filter
getFilter()
Gets the filter used to define constraints on the features that will be retrieved by this Query.String
getHandle()
Get the handle (mnemonic name) that will be associated with this Query.Hints
getHints()
Get hints that have been set to control the query execution.List<Join>
getJoins()
The list of joins for this query.int
getMaxFeatures()
Get the maximum number of features that will be retrieved by this Query.URI
getNamespace()
Get the namespace of the feature type to be queried.List<PropertyName>
getProperties()
Get the names of the properties that this Query will retrieve values for as part of the returned FeatureCollection.String[]
getPropertyNames()
Get the names of the properties that this Query will retrieve as part of the returned FeatureCollection.SortBy[]
getSortBy()
SortBy results according to indicated property and order.Integer
getStartIndex()
Get the index of the first feature to retrieve.String
getTypeName()
Get the name of the feature type to be queried.String
getVersion()
Defines version or version range requested.int
hashCode()
Hashcode based on all parameters other than the handle.boolean
isMaxFeaturesUnlimited()
Check if this query allows an unlimited number of features to be returned.boolean
retrieveAllProperties()
Convenience method to determine if the query should retrieve all properties defined in the schema of the feature data source.void
setAlias(String alias)
Sets the type name alias.void
setCoordinateSystem(CoordinateReferenceSystem system)
Provide an override coordinate system to apply to features retrieved by this Query.void
setCoordinateSystemReproject(CoordinateReferenceSystem system)
Request that features retrieved by this Query be reprojected into the given coordinate system.void
setFilter(Filter filter)
Sets the filter to constrain the features that will be retrieved by this Query.void
setHandle(String handle)
Set the handle (mnemonic name) that will be associated with this Query.void
setHints(Hints hints)
Set hints to control the query execution.void
setMaxFeatures(int maxFeatures)
Sets the maximum number of features that should be retrieved by this query.void
setNamespace(URI namespace)
Set the namespace of the feature type to be queried.void
setProperties(List<PropertyName> propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection.void
setPropertyNames(String... propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection.void
setPropertyNames(List<String> propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection.void
setSortBy(SortBy... sortBy)
Sets the sort by information.void
setStartIndex(Integer startIndex)
Set the index of the first feature to retrieve.void
setTypeName(String typeName)
Sets the name of the feature type to be queried.void
setVersion(int index)
void
setVersion(String version)
Set the version of features to retrieve where this is supported by the data source being queried.void
setVersion(Date date)
void
setVersion(Date startTime, Date endTime)
void
setVersion(ResourceId history)
void
setVersion(Version.Action action)
String
toString()
Return a string representation of this Query.
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Field Detail
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INCLUDE_MANDATORY_PROPS
public static Hints.Key INCLUDE_MANDATORY_PROPS
When specifying properties to select, setting this hint flag true tells the datastore to include mandatory properties (i.e. properties with minOccurs >= 1) in the end result, irrespective of whether they are not included in the list of properties.Datastores may implement adding all mandatory properties to the end result when this flag is set to true. For example:
Object includeProps = query.getHints().get(Query.INCLUDE_MANDATORY_PROPS); if (includeProps instanceof Boolean && ((Boolean)includeProps).booleanValue()) { query.setProperties (DataUtilities.addMandatoryProperties(type, query.getProperties())); }
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NO_NAMESPACE
public static final URI NO_NAMESPACE
Constant (actually null) used to represent no namespace restrictions on the returned result, should be considered ANY_URI
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DEFAULT_MAX
public static final int DEFAULT_MAX
So getMaxFeatures does not return null we use a very large number.- See Also:
- Constant Field Values
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ALL
public static final Query ALL
Implements a query that will fetch all features from a datasource. This query should retrieve all properties, with no maxFeatures, no filtering, and the default featureType.
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FIDS
public static final Query FIDS
Implements a query that will fetch all the FeatureIDs from a datasource. This query should retrieve no properties, with no maxFeatures, no filtering, and the a featureType with no attribtues.
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NO_NAMES
public static final String[] NO_NAMES
A constant (empty String array) that can be used with setPropertyNames(String[]) to indicate that no properties are to be retrieved.Note the query will still return a result - limited to FeatureIDs.
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ALL_NAMES
public static final String[] ALL_NAMES
A constant (valuenull
) that can be used with setPropertyNames(String[]) to indicate that all properties are to be retrieved.
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NO_PROPERTIES
public static final List<PropertyName> NO_PROPERTIES
A constant (empty String array) that can be used with #setProperties(Collection) to indicate that no properties are to be retrieved. Note the query will still return a result - limited to FeatureIDs.
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ALL_PROPERTIES
public static final List<PropertyName> ALL_PROPERTIES
A constant (valuenull
) that can be used with #setProperties(Collection) to indicate that all properties are to be retrieved.
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properties
protected List<PropertyName> properties
The properties to fetch
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maxFeatures
protected int maxFeatures
The maximum numbers of features to fetch
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startIndex
protected Integer startIndex
The index of the first feature to process
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filter
protected Filter filter
The filter to constrain the request.
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typeName
protected String typeName
The typeName to get
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alias
protected String alias
The optional alias for type name
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namespace
protected URI namespace
The namespace to get
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handle
protected String handle
The handle associated with this query.
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coordinateSystem
protected CoordinateReferenceSystem coordinateSystem
Coordinate System associated with this query
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coordinateSystemReproject
protected CoordinateReferenceSystem coordinateSystemReproject
Reprojection associated associated with this query
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sortBy
protected SortBy[] sortBy
Sorting for the query
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version
protected String version
The version according to WFS 1.0 and 1.1 specs
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hints
protected Hints hints
The hints to be used during query execution
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Constructor Detail
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Query
public Query()
Default constructor. Use setter methods to configure the Query before use (the default Query will retrieve all features).
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Query
public Query(String typeName)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve
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Query
public Query(String typeName, Filter filter)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.filter
- the OGC filter to constrain the request.
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Query
public Query(String typeName, Filter filter, String... properties)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.filter
- the OGC filter to constrain the request.properties
- an array of the properties to fetch.
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Query
public Query(String typeName, Filter filter, List<PropertyName> properties)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.filter
- the OGC filter to constrain the request.properties
- a list of the properties to fetch.
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Query
public Query(String typeName, Filter filter, int maxFeatures, String[] propNames, String handle)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.filter
- the OGC filter to constrain the request.maxFeatures
- the maximum number of features to be returned.propNames
- an array of the properties to fetch.handle
- the name to associate with this query.
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Query
public Query(String typeName, Filter filter, int maxFeatures, List<PropertyName> properties, String handle)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.filter
- the OGC filter to constrain the request.maxFeatures
- the maximum number of features to be returned.properties
- a list of the properties to fetch.handle
- the name to associate with this query.
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Query
public Query(String typeName, URI namespace, Filter filter, int maxFeatures, String[] propNames, String handle)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.namespace
- Namespace for provided typeName, or null if unspecifiedfilter
- the OGC filter to constrain the request.maxFeatures
- the maximum number of features to be returned.propNames
- an array of the properties to fetch.handle
- the name to associate with the query.
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Query
public Query(String typeName, URI namespace, Filter filter, int maxFeatures, List<PropertyName> properties, String handle)
Constructor.- Parameters:
typeName
- the name of the featureType to retrieve.namespace
- Namespace for provided typeName, or null if unspecifiedfilter
- the OGC filter to constrain the request.maxFeatures
- the maximum number of features to be returned.properties
- a list of the property names to fetch.handle
- the name to associate with the query.
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Query
public Query(Query query)
Copy contructor.- Parameters:
query
- the query to copy
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Method Detail
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getPropertyNames
public String[] getPropertyNames()
Get the names of the properties that this Query will retrieve as part of the returned FeatureCollection.- Returns:
- the attributes to be used in the returned FeatureCollection.
- See Also:
retrieveAllProperties()
- TODO:
- REVISIT: make a FidProperties object, instead of an array size 0. I think Query.FIDS fills this role to some degree. Query.FIDS.equals( filter ) would meet this need?
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setPropertyNames
public void setPropertyNames(String... propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection. As well as an array of names, the following constants can be used:- ALL_NAMES to retrieve all properties.
- NO_NAMES to indicate no properties are required, just feature IDs.
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getProperties
public List<PropertyName> getProperties()
Get the names of the properties that this Query will retrieve values for as part of the returned FeatureCollection.- Returns:
- the xpath expressions to be used in the returned FeatureCollection.
- See Also:
retrieveAllProperties()
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setProperties
public void setProperties(List<PropertyName> propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection. As well as an array of names, the following constants can be used:- ALL_PROPERTIES to retrieve all properties.
- NO_PROPERTIES to indicate no properties are required, just feature IDs.
- Parameters:
propNames
- the names of the properties to retrieve or one of ALL_PROPERTIES or NO_PROPERTIES.
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setPropertyNames
public void setPropertyNames(List<String> propNames)
Set the names of the properties that this Query should retrieve as part of the returned FeatureCollection.The available properties can be determined with FeatureSource.getSchema(). If properties that are not part of the source's schema are requested an exception will be thrown.
- Parameters:
propNames
- the names of the properties to retrieve or ALL_NAMES; an empty List can be passed in to indicate that only feature IDs should be retrieved- TODO:
- REVISIT: This syntax is really obscure. Consider having an fid or featureID propertyName that datasource implementors look for instead of looking to see if the list size is 0.
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retrieveAllProperties
public boolean retrieveAllProperties()
Convenience method to determine if the query should retrieve all properties defined in the schema of the feature data source. This is equivalent to testing if getPropertyNames() returns ALL_NAMES.- Returns:
- true if all properties will be retrieved by this Query; false otherwise
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getMaxFeatures
public int getMaxFeatures()
Get the maximum number of features that will be retrieved by this Query.Note: This is the only method that is not directly out of the Query element in the WFS specification. It is instead a part of a GetFeature request, which can hold one or more queries. But each of those in turn will need a maxFeatures, so it is needed here.
If the value returned here is max integer then the number of features should not be limited.
- Returns:
- the maximum number of features that will be retrieved by this query
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isMaxFeaturesUnlimited
public boolean isMaxFeaturesUnlimited()
Check if this query allows an unlimited number of features to be returned.- Returns:
- true maxFeatures is less then zero, or equal to Integer.MAX_VALUE.
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setMaxFeatures
public void setMaxFeatures(int maxFeatures)
Sets the maximum number of features that should be retrieved by this query. The default is to retrieve all features.- Parameters:
maxFeatures
- the maximum number of features to retrieve
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getStartIndex
public Integer getStartIndex()
Get the index of the first feature to retrieve.- Returns:
- the index of the first feature to retrieve or
null
if no start index is defined.
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setStartIndex
public void setStartIndex(Integer startIndex)
Set the index of the first feature to retrieve. This can be used in conjuction with setMaxFeatures(int) to 'page' through a feature data source.- Parameters:
startIndex
- index of the first feature to retrieve ornull
to indicate no start index- Throws:
IllegalArgumentException
- if startIndex is less than 0
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getFilter
public Filter getFilter()
Gets the filter used to define constraints on the features that will be retrieved by this Query.- Returns:
- The filter that defines constraints on the query.
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setFilter
public void setFilter(Filter filter)
Sets the filter to constrain the features that will be retrieved by this Query. If no filter is set all features will be retrieved (taking into account any bounds set via setMaxFeatures(int) and setStartIndex(java.lang.Integer)).The default is Filter.INCLUDE.
- Parameters:
filter
- the OGC filter which features must pass through to be retrieved by this Query.
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getTypeName
public String getTypeName()
Get the name of the feature type to be queried.- Returns:
- the name of the feature type to be returned with this query.
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setTypeName
public void setTypeName(String typeName)
Sets the name of the feature type to be queried. If no typename is specified, then the data source's default type will be used. When working with sources such as shapefiles that only support one feature type this method can be ignored.- Parameters:
typeName
- the name of the featureType to retrieve.
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getAlias
public String getAlias()
An alias substitutable forgetTypeName()
.This value is typically used in a join query in which the join filter requires disambiguation due to property name overlaps between joined types.
- Since:
- 8.0
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setAlias
public void setAlias(String alias)
Sets the type name alias.- Since:
- 8.0
- See Also:
getAlias()
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getNamespace
public URI getNamespace()
Get the namespace of the feature type to be queried.- Returns:
- the gml namespace of the feature type to be returned with this query
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setNamespace
public void setNamespace(URI namespace)
Set the namespace of the feature type to be queried.
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getHandle
public String getHandle()
Get the handle (mnemonic name) that will be associated with this Query. The handle is used in logging and error reporting.- Returns:
- the name to refer to this query.
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setHandle
public void setHandle(String handle)
Set the handle (mnemonic name) that will be associated with this Query. The handle is used in logging and error reporting.- Parameters:
handle
- the name to refer to this query.
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getVersion
public String getVersion()
Defines version or version range requested.From WFS Spec: The version attribute is included in order to accommodate systems that support feature versioning. A value of ALL indicates that all versions of a feature should be fetched. Otherwise an integer, n, can be specified to return the n th version of a feature. The version numbers start at '1' which is the oldest version. If a version value larger than the largest version is specified then the latest version is return. The default action shall be for the query to return the latest version. Systems that do not support versioning can ignore the parameter and return the only version that they have.
GeoTools employs the following options:
setVersion(Date)
: "date: dow mon dd hh:mm:ss zzz yyyy"setVersion(int)
: "index"- {@link #setVersion(org.geotools.api.filter.identity.Version.Action)): "PREVIOUS", "LAST", "NEXT", "FIRST", "ALL"
- {@link #setVersion(Date, Date): "start: dow mon dd hh:mm:ss zzz yyyy end: dow mon dd hh:mm:ss zzz yyyy"
- Returns:
- the version of the feature to return, or
null
for LAST.
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setVersion
public void setVersion(int index)
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setVersion
public void setVersion(Date date)
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setVersion
public void setVersion(Version.Action action)
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setVersion
public void setVersion(ResourceId history)
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setVersion
public void setVersion(String version)
Set the version of features to retrieve where this is supported by the data source being queried.- Since:
- 2.4
- See Also:
getVersion() for explanation
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getCoordinateSystem
public CoordinateReferenceSystem getCoordinateSystem()
Get the coordinate system to use as an override for features retrieved by this Query.- Returns:
- The coordinate system to be returned for Features from this Query (override the set coordinate system).
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setCoordinateSystem
public void setCoordinateSystem(CoordinateReferenceSystem system)
Provide an override coordinate system to apply to features retrieved by this Query.This denotes a request to temporarily override the coordinate system contained in the feature data source being queried. The same coordinate values will be used, but the features retrieved will appear in this Coordinate System.
This change is not persistent and only applies to the features returned by this Query. If used in conjunction with
getCoordinateSystemReproject()
the reprojection will occur fromgetCoordinateSystem()
togetCoordinateSystemReproject()
.- Parameters:
system
- the coordinate system to apply to features retrieved by this Query
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getCoordinateSystemReproject
public CoordinateReferenceSystem getCoordinateSystemReproject()
If reprojection has been requested, this returns the coordinate system that features retrieved by this Query will be reprojected into.- Returns:
- the coordinate system that features will be reprojected into (if set)
- See Also:
setCoordinateSystemReproject( CoordinateReferenceSystem )
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setCoordinateSystemReproject
public void setCoordinateSystemReproject(CoordinateReferenceSystem system)
Request that features retrieved by this Query be reprojected into the given coordinate system.If used in conjunction with
setCoordinateSystem(CoordinateReferenceSystem)
the reprojection will occur from the overridden coordinate system to the system specified here.
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getSortBy
public SortBy[] getSortBy()
SortBy results according to indicated property and order.SortBy is part of the Filter 1.1 specification, it is referenced by WFS1.1 and Catalog 2.0.x specifications and is used to organize results. The SortBy's are ment to be applied in order:
- SortBy( year, ascending )
- SortBy( month, decsending )
[year=2002 month=4],[year=2002 month=3],[year=2002 month=2], [year=2002 month=1],[year=2003 month=12],[year=2002 month=4],
SortBy should be considered at the same level of abstraction as Filter, and like Filter you may sort using properties not listed in getPropertyNames.
At a technical level the interface SortBy2 is used to indicate the additional requirements of a GeoTools implementation. The pure WFS 1.1 specification itself is limited to SortBy.
- Returns:
- SortBy array or order of application
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setSortBy
public void setSortBy(SortBy... sortBy)
Sets the sort by information.
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getHints
public Hints getHints()
Get hints that have been set to control the query execution.- Returns:
- hints that are set (may be empty)
- See Also:
setHints(Hints) for more explanation
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setHints
public void setHints(Hints hints)
Set hints to control the query execution.Hints can control such things as:
- the GeometryFactory to be used
- a generalization distance to be applied
- the fetch size to be used in JDBC queries
Note: Data sources may ignore hints (depending on their values) and no mechanism currently exists to discover which hints where actually used during the query's execution.
- Parameters:
hints
- the hints to apply- See Also:
Hints.FEATURE_DETACHED
,Hints.JTS_GEOMETRY_FACTORY
,Hints.JTS_COORDINATE_SEQUENCE_FACTORY
,Hints.JTS_PRECISION_MODEL
,Hints.JTS_SRID
,Hints.GEOMETRY_DISTANCE
,Hints.FEATURE_2D
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hashCode
public int hashCode()
Hashcode based on all parameters other than the handle.
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equals
public boolean equals(Object obj)
Equality based on all query parameters other than the handle.
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toString
public String toString()
Return a string representation of this Query.
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