org.apache.cayenne.map
Class DerivedDbAttribute

java.lang.Object
  org.apache.cayenne.map.Attribute
      org.apache.cayenne.map.DbAttribute
          org.apache.cayenne.map.DerivedDbAttribute

All Implemented Interfaces:

java.io.Serializable, CayenneMapEntry, XMLSerializable

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(%@)

Author:

Andrei Adamchik

See Also:

Serialized Form

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.apache.cayenne.map.DbAttribute

generated, mandatory, maxLength, precision, primaryKey, type

Fields inherited from class org.apache.cayenne.map.Attribute

entity, name

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) Adds parameter.
void	clearParams()
void	encodeAsXML(XMLEncoder encoder) Prints itself as XML to the provided XMLEncoder.
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.apache.cayenne.map.DbAttribute

getMaxLength, getPrecision, getType, isForeignKey, isGenerated, isMandatory, isPrimaryKey, setGenerated, setMandatory, setMaxLength, setPrecision, setPrimaryKey, setType

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

getEntity, getName, getParent, setEntity, setName, setParent

Methods inherited from class java.lang.Object

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

DerivedDbAttribute

public DerivedDbAttribute()

Constructor for DerivedDbAttribute.

DerivedDbAttribute

public DerivedDbAttribute(java.lang.String name)

Constructor for DerivedDbAttribute.

DerivedDbAttribute

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

Constructor for DerivedDbAttribute.

DerivedDbAttribute

public DerivedDbAttribute(DbEntity entity,
                          DbAttribute parentProto)

Creates and initializes a derived attribute with an attribute of a parent entity.

Method Detail

encodeAsXML

public void encodeAsXML(XMLEncoder encoder)

Prints itself as XML to the provided XMLEncoder.

Specified by:

encodeAsXML in interface XMLSerializable

Overrides:

encodeAsXML in class DbAttribute

Since:

1.1

getAliasedName

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

Overrides:

getAliasedName in class DbAttribute

isGroupBy

public boolean isGroupBy()

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

setGroupBy

public void setGroupBy(boolean flag)

getParams

public java.util.List getParams()

Returns the params.

Returns:

List

getExpressionSpec

public java.lang.String getExpressionSpec()

Returns the expressionSpec.

addParam

public void addParam(DbAttribute param)

Adds parameter.

removeParam

public void removeParam(DbAttribute param)

clearParams

public void clearParams()

setExpressionSpec

public void setExpressionSpec(java.lang.String expressionSpec)

Sets the expressionSpec.