uk.ac.ed.epcc.webapp.model.data

Class FieldExpression<T,X extends DataObject>

java.lang.Object

uk.ac.ed.epcc.webapp.model.data.FieldExpression<T,X>

Type Parameters:

T - data type

X - target type

All Implemented Interfaces:

Accessor<T,X>, GroupingSQLValue<T>, SQLAccessor<T,X>, SQLExpression<T>, SQLValue<T>, FieldSQLExpression<T,X>, FieldValue<T,X>, Targetted<T>

Direct Known Subclasses:

BooleanFieldExpression, DateFieldExpression, NumberFieldExpression, StreamDataFieldExpression, StringFieldExpression, TimestampDateFieldExpression

public abstract class FieldExpression<T,X extends DataObject>
extends java.lang.Object
implements FieldSQLExpression<T,X>

Abstract class for SQL fields that can be used in expressions. Sub-classes effectively have to forward the methods equivalent to Accessor targeted on Record.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Class<X>	filter_type
static Feature	LOG_FETCH
protected java.lang.String	name
protected Repository	repository
protected java.lang.Class<T>	target

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FieldExpression(java.lang.Class<X> filter_type, Repository repository, java.lang.Class<T> target, java.lang.String name)

Method Summary

Modifier and Type	Method and Description
int	add(java.lang.StringBuilder sb, boolean qualify) Add the expression to a StringBuilder
boolean	canSet() does this Accessor support setting values.
boolean	equals(java.lang.Object obj)
java.lang.String	getFieldName() Get the corresponding field name.
java.lang.Class<X>	getFilterType()
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.
protected abstract T	getValue(Repository.Record r)
T	getValue(X r) get the value from the target object
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.
void	setObject(java.sql.PreparedStatement stmt, int pos, T value) Add an object of the target type to a prepared statement doing any necessary type conversion to map it to the SQL representation of the object (as generated by FieldValue.addField(StringBuilder, boolean) Note this is only valid if canSet from SQLAccessor returns true.
protected abstract void	setValue(Repository.Record r, T value)
void	setValue(X r, T value) Set value if supported otherwise throw a UnsupportedOperationException.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.ed.epcc.webapp.model.data.FieldValue

addField

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

addGroup, checkContentsCanGroup, getGroupParameters, groupingIsomorphic

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

groupingIsomorphic

Field Detail

LOG_FETCH

public static final Feature LOG_FETCH

repository

protected final Repository repository

name

protected final java.lang.String name

target

protected final java.lang.Class<T> target

filter_type

protected final java.lang.Class<X extends DataObject> filter_type

Constructor Detail

FieldExpression

protected FieldExpression(java.lang.Class<X> filter_type,
                          Repository repository,
                          java.lang.Class<T> target,
                          java.lang.String name)

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

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

getTarget

public final 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

getFieldName

public java.lang.String getFieldName()

Description copied from interface: FieldValue

Get the corresponding field name. This should not be used to create SQL fragments but can be used to identify Repository field names

Specified by:

getFieldName in interface FieldValue<T,X extends DataObject>

Returns:

database field name

setObject

public void setObject(java.sql.PreparedStatement stmt,
                      int pos,
                      T value)
               throws java.sql.SQLException

Description copied from interface: FieldValue

Add an object of the target type to a prepared statement doing any necessary type conversion to map it to the SQL representation of the object (as generated by FieldValue.addField(StringBuilder, boolean) Note this is only valid if canSet from SQLAccessor returns true.

Specified by:

setObject in interface FieldValue<T,X extends DataObject>

Throws:

java.sql.SQLException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

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

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

canSet

public boolean canSet()

Description copied from interface: Accessor

does this Accessor support setting values.

Specified by:

canSet in interface Accessor<T,X extends DataObject>

Returns:

getValue

protected abstract T getValue(Repository.Record r)

getValue

public final T getValue(X r)

Description copied from interface: Accessor

get the value from the target object

Specified by:

getValue in interface Accessor<T,X extends DataObject>

Parameters:

r - target object

Returns:

value

setValue

protected abstract void setValue(Repository.Record r,
                                 T value)

setValue

public final void setValue(X r,
                           T value)

Description copied from interface: Accessor

Set value if supported otherwise throw a UnsupportedOperationException.

Specified by:

setValue in interface Accessor<T,X extends DataObject>

getFilterType

public final java.lang.Class<X> getFilterType()

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