uk.ac.ed.epcc.webapp.jdbc.expr

Class DerefSQLExpression<H extends DataObject,R extends DataObject,T>

java.lang.Object

uk.ac.ed.epcc.webapp.jdbc.expr.DerefSQLExpression<H,R,T>

Type Parameters:

H - home object

R - remote object

T - target type of expression

All Implemented Interfaces:

GroupingSQLValue<T>, SQLExpression<T>, SQLValue<T>, Targetted<T>

Direct Known Subclasses:

DateDerefSQLExpression

public class DerefSQLExpression<H extends DataObject,R extends DataObject,T>
extends java.lang.Object
implements SQLExpression<T>

A join based SQLExpression for accessing remote tables.

Field Summary

Fields

Modifier and Type	Field and Description
protected IndexedSQLValue<H,R>	a
protected SQLExpression<T>	remote_expression
protected SQLFilter	required_filter

Constructor Summary

Constructors

Modifier	Constructor and Description
	DerefSQLExpression(IndexedSQLValue<H,R> a, SQLExpression<T> expr)
protected	DerefSQLExpression(IndexedSQLValue<H,R> a, SQLExpression<T> expr, SQLFilter fil)

Method Summary

Modifier and Type	Method and Description
int	add(java.lang.StringBuilder sb, boolean qualify) Add the expression to a StringBuilder
static <H extends DataObject,R extends DataObject> DerefSQLExpression<H,R,? extends java.lang.Number>	convertToMillis(SQLContext sql, DerefSQLExpression<H,R,java.util.Date> expr) helper method to allow a SQLContext to convert DerefSQLExpressions
static <H extends DataObject,R extends DataObject> DerefSQLExpression<H,R,? extends java.lang.Number>	convertToSeconds(SQLContext sql, DerefSQLExpression<H,R,java.util.Date> expr) helper method to allow a SQLContext to convert DerefSQLExpressions
boolean	equals(java.lang.Object obj)
java.util.List<PatternArgument>	getParameters(java.util.List<PatternArgument> list) Add parameters for this value to a list.
SQLFilter	getRequiredFilter() Get an SQLFilter required to be added to the filter set.
java.lang.Class<T>	getTarget() Get the type of the returned object as far as it is known.
int	hashCode()
T	makeObject(java.sql.ResultSet rs, int pos) Extract a result of the expression from a ResultSet into an object of the specified type.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface uk.ac.ed.epcc.webapp.jdbc.expr.SQLExpression

groupingIsomorphic

Methods inherited from interface uk.ac.ed.epcc.webapp.jdbc.expr.GroupingSQLValue

addGroup, checkContentsCanGroup, getGroupParameters

Field Detail

a

protected final IndexedSQLValue<H extends DataObject,R extends DataObject> a

remote_expression

protected final SQLExpression<T> remote_expression

required_filter

protected final SQLFilter required_filter

Constructor Detail

DerefSQLExpression

public DerefSQLExpression(IndexedSQLValue<H,R> a,
                          SQLExpression<T> expr)
                   throws java.lang.Exception

Throws:

java.lang.Exception

DerefSQLExpression

protected DerefSQLExpression(IndexedSQLValue<H,R> a,
                             SQLExpression<T> expr,
                             SQLFilter fil)

Method Detail

add

public int add(java.lang.StringBuilder sb,
               boolean qualify)

Description copied from interface: SQLValue

Add the expression to a StringBuilder

Specified by:

add in interface SQLValue<T>

Parameters:

sb - StringBuilder to modify

qualify - boolean should fields be qualified with the table name

Returns:

number of fields added

getParameters

public java.util.List<PatternArgument> getParameters(java.util.List<PatternArgument> list)

Description copied from interface: SQLValue

Add parameters for this value to a list.

Specified by:

getParameters in interface SQLValue<T>

Parameters:

list - to modify

Returns:

modified list of parameter objects

makeObject

public T makeObject(java.sql.ResultSet rs,
                    int pos)
             throws DataException,
                    java.sql.SQLException

Description copied from interface: SQLValue

Extract a result of the expression from a ResultSet into an object of the specified type. Note that this method is also used to extract the result of functions over the result type.

Specified by:

makeObject in interface SQLValue<T>

Parameters:

rs - ResultSet

Returns:

produced object

Throws:

DataException

java.sql.SQLException

getRequiredFilter

public SQLFilter getRequiredFilter()

Description copied from interface: SQLValue

Get an SQLFilter required to be added to the filter set. This is usually to implement a join.

Specified by:

getRequiredFilter in interface SQLValue<T>

Returns:

null or SQLFilter

getTarget

public java.lang.Class<T> getTarget()

Description copied from interface: Targetted

Get the type of the returned object as far as it is known. Normally this should be the erasure type corresponding to T.

Specified by:

getTarget in interface Targetted<T>

Returns:

Class object for return type

hashCode

public int hashCode()

Specified by:

hashCode in interface SQLExpression<T>

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface SQLExpression<T>

Overrides:

equals in class java.lang.Object

convertToMillis

public static <H extends DataObject,R extends DataObject> DerefSQLExpression<H,R,? extends java.lang.Number> convertToMillis(SQLContext sql,
                                                                                                                             DerefSQLExpression<H,R,java.util.Date> expr)

helper method to allow a SQLContext to convert DerefSQLExpressions

Parameters:

sql - SQLContext

expr -

Returns:

convertToSeconds

public static <H extends DataObject,R extends DataObject> DerefSQLExpression<H,R,? extends java.lang.Number> convertToSeconds(SQLContext sql,
                                                                                                                              DerefSQLExpression<H,R,java.util.Date> expr)

helper method to allow a SQLContext to convert DerefSQLExpressions

Parameters:

sql - SQLContext

expr -

Returns: