DerivedDbAttribute

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org.objectstyle.cayenne.map
Class DerivedDbAttribute

java.lang.Object
  org.objectstyle.cayenne.map.MapObject
      org.objectstyle.cayenne.map.Attribute
          org.objectstyle.cayenne.map.DbAttribute
              org.objectstyle.cayenne.map.DerivedDbAttribute

All Implemented Interfaces:: org.objectstyle.cayenne.util.CayenneMapEntry

public class DerivedDbAttribute
extends DbAttribute

A DerivedDbAttribute is a DbAttribute that resolves to an SQL expression based on a set of other attributes. DerivedDbAttribute's allow to build expressions like "count(id)", "sum(price)", etc.

Internally DerivedDbAttribute is defined as a specification string and a set of substitution DbAttribute parameters. Specification string is an SQL expression that contains placeholders (%@) for attribute parameters, for example:

sum(%@) + sum(%@)

Field Summary

static java.lang.String ATTRIBUTE_TOKEN


protected java.lang.String expressionSpec


protected boolean groupBy


protected java.util.List params


Fields inherited from class org.objectstyle.cayenne.map.DbAttribute

mandatory, maxLength, precision, primaryKey, type

Fields inherited from class org.objectstyle.cayenne.map.MapObject

objName, objParent

Constructor Summary

DerivedDbAttribute()
          Constructor for DerivedDbAttribute.

DerivedDbAttribute(DbEntity entity, DbAttribute parentProto)
          Creates and initializes a derived attribute with an attribute of a parent entity.

DerivedDbAttribute(java.lang.String name)
          Constructor for DerivedDbAttribute.

DerivedDbAttribute(java.lang.String name, int type, DbEntity entity, java.lang.String spec)
          Constructor for DerivedDbAttribute.

Method Summary

void addParam(DbAttribute param)
          Sets the params.

void clearParams()


java.lang.String getAliasedName(java.lang.String alias)


java.lang.String getExpressionSpec()
          Returns the expressionSpec.

java.util.List getParams()
          Returns the params.

boolean isGroupBy()
          Returns true if this attribute is used in GROUP BY clause of the parent entity.

void removeParam(DbAttribute param)


void setExpressionSpec(java.lang.String expressionSpec)
          Sets the expressionSpec.

void setGroupBy(boolean flag)


Methods inherited from class org.objectstyle.cayenne.map.DbAttribute

getMaxLength, getPrecision, getType, isMandatory, isPrimaryKey, setMandatory, setMaxLength, setPrecision, setPrimaryKey, setType, toString, toStringBuffer

Methods inherited from class org.objectstyle.cayenne.map.Attribute

getEntity, setEntity

Methods inherited from class org.objectstyle.cayenne.map.MapObject

getName, getParent, setName, setParent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

ATTRIBUTE_TOKEN

public static final java.lang.String ATTRIBUTE_TOKEN

See Also:: Constant Field Values

expressionSpec

protected java.lang.String expressionSpec

params

protected java.util.List params

groupBy

protected boolean groupBy

Constructor Detail