INT32 MgFeatureQueryOptions::AddComputedProperty	(	CREFSTRING	aliasName,
		CREFSTRING	expression
	)

Define an alias for a computed property and an expression for what is to be computed. In this SQL example, "select min(aDouble + aSingle) as minF, min(anInt16 + anInt16) as minI from featclass;", minF and minI are computed properties. Call this method for each computed property that you add.

.NET Syntax

int AddComputedProperty(string aliasName, string expression);

Java Syntax

int AddComputedProperty(String aliasName, String expression);

PHP Syntax

int AddComputedProperty(string aliasName, string expression);

Parameters:

aliasName	(String/string) The name of the computed property.
expression	(String/string) The expression to be associated with the name of the computed property.

Returns:

Returns the total number of properties added.

Example (PHP)

 <?php
 $queryOptions->AddComputedProperty("minF", "aDouble + aSingle");
 $queryOptions->AddComputedProperty("minI", "anInt64 + anInt16");
 $featureService->SelectFeatures($featureSrcResourceId, $featClassName, $queryOptions);
 $featureService->SelectFeatures($featureSrcResourceId, $featClassName, $queryOptions);

 ?>
 sqlplus> select min(aDouble + aSingle) as minF, min(anInt16 + anInt16) as minI from featclass;

Example (C#)

 using OSGeo.MapGuide;
 private MgFeatureQueryOptions queryOptions;
 private MgFeatureService featureService;
 private String className = "SdfFeatureClass";
 // the SDF file identified by this MgResourceIdentifier exists in the repository
 private MgResourceIdentifier resourceId;
 private MgFeatureReader featureReader;

 resourceId = new MgResourceIdentifier("Library://PlatformApiDocTests/SdfFeatureClass.FeatureSource");
 queryOptions = new MgFeatureQueryOptions();
 queryOptions.AddFeatureProperty("FeatId");
 queryOptions.AddFeatureProperty("aDouble");
 queryOptions.AddComputedProperty("ceilADouble", "Ceil(aDouble)");
 featureReader = featureService.SelectFeatures(resourceId, className, queryOptions);

Exceptions:

MgInvalidArgumentException

if aliasName or expression is empty