com.objectwave.persist.constraints
Class Constraint

java.lang.Object
  |
  +--com.objectwave.persist.constraints.Constraint

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

Direct Known Subclasses:

ConstraintAnyOf, ConstraintBetween, ConstraintBoolean, ConstraintCompare, ConstraintIsNull, ConstraintSubSelect, CrossField

public abstract class Constraint

extends java.lang.Object

implements java.lang.Cloneable, java.io.Serializable

Abstract class for all query constraints. Remember, after creating one of these guys, you should add a line to the ConstraintFactory's static{} block.

Version:

$Id: Constraint.java,v 2.1 2002/02/08 22:41:28 dave_hoag Exp $

Author:

Steven Sinclair

See Also:

Serialized Form

Field Summary

protected java.lang.String	columnName
protected static ObjectFormatter	defaultObjectFormatter
protected ObjectFormatter	objectFormatter

Constructor Summary

Constraint()

Method Summary

abstract boolean	checkConstraint(java.lang.Object dataField, java.lang.Object queryField) Check to see if a given object passes this constraint.
boolean	checkConstraint(SQLQuery query, Persistence poolElement, java.lang.Object dataField, java.lang.Object queryField)
protected static java.lang.Class	classOfField(java.lang.String field, java.lang.Object baseObj) This is a handy method for formatting output and validating input for specific fields.
java.lang.Object	clone() Publicize the clone method.
abstract java.lang.String	constructQueryString() Return the string which will appear in the query string.
boolean	equals(java.lang.Object obj) A rudimentary but effective equals() method for subclasses of Constraint.
boolean	findField(java.lang.String field)
protected java.lang.String	formatString(java.lang.String input) This is to abstract the need to get input in the correct format for a given field object, based on the class of the field indicated by getField() and getPersistence().
abstract void	fromString(java.lang.String str) Parse the string.
java.lang.String	getColumnName()
java.lang.String	getField() A given constraint instance will be associated with a field.
boolean	getNot() Gets the Not attribute of the Constraint object
ObjectFormatter	getObjectFormatter()
Persistence	getPersistence() The field is specified as a field on a given persistent object.
abstract java.util.Enumeration	getStaticList() Gets the StaticList attribute of the Constraint object
abstract java.lang.String	getType() This is a unique, readable string identifying the constraint type (ex, anyof, null)
boolean	isComparisonValueFromPersistentObject()
boolean	isUsingColumnName()
void	setColumnName(java.lang.String colName)
void	setField(java.lang.String field) Sets the Field attribute of the Constraint object
void	setNot(boolean not) Sets the Not attribute of the Constraint object
void	setObjectFormatter(ObjectFormatter value)
void	setPersistence(Persistence p) Sets the Persistence attribute of the Constraint object
protected static java.lang.String	sqlString(java.lang.String str) Provide a generic method for converting a string to a SQL-type string:
abstract void	staticListInsert(java.lang.String field) Each type of constraint will have a specific set of fields associated with it.
abstract java.lang.String	stringify() Stringify the object.
protected java.lang.Object	stringToObject(java.lang.String str, java.lang.Class classOfStr)
java.lang.String	toString() toString returns the stringified object.

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

defaultObjectFormatter

protected static ObjectFormatter defaultObjectFormatter

columnName

protected java.lang.String columnName

objectFormatter

protected transient ObjectFormatter objectFormatter

Constructor Detail

Constraint

public Constraint()

Method Detail

classOfField

protected static java.lang.Class classOfField(java.lang.String field,
                                              java.lang.Object baseObj)
                                       throws java.lang.NoSuchFieldException

This is a handy method for formatting output and validating input for specific fields. baseObj would presumably be getPersistence().

Parameters:

field -

baseObj -

Returns:

Throws:

java.lang.NoSuchFieldException

sqlString

protected static java.lang.String sqlString(java.lang.String str)

Provide a generic method for converting a string to a SQL-type string:

Parameters:

str -

Returns:

setObjectFormatter

public void setObjectFormatter(ObjectFormatter value)

Parameters:

value - The new ObjectFormatter value

setField

public void setField(java.lang.String field)

Sets the Field attribute of the Constraint object

Parameters:

field - The new Field value

setNot

public void setNot(boolean not)

Sets the Not attribute of the Constraint object

Parameters:

not - The new Not value

setPersistence

public void setPersistence(Persistence p)

Sets the Persistence attribute of the Constraint object

Parameters:

p - The new Persistence value

setColumnName

public void setColumnName(java.lang.String colName)

Parameters:

colName - The new ColumnName value

getObjectFormatter

public ObjectFormatter getObjectFormatter()

Returns:

The ObjectFormatter value

getField

public java.lang.String getField()

A given constraint instance will be associated with a field. Since most constraints can be preceeded by "not", it has been defined here, in the base class.

Returns:

The Field value

getNot

public boolean getNot()

Gets the Not attribute of the Constraint object

Returns:

The Not value

getPersistence

public Persistence getPersistence()

The field is specified as a field on a given persistent object. This is the persistent object with that field.

Returns:

The Persistence value

getStaticList

public abstract java.util.Enumeration getStaticList()

Gets the StaticList attribute of the Constraint object

Returns:

The StaticList value

getType

public abstract java.lang.String getType()

This is a unique, readable string identifying the constraint type (ex, anyof, null)

Returns:

The Type value

isComparisonValueFromPersistentObject

public boolean isComparisonValueFromPersistentObject()

Returns:

true If the constraint object should use the comparison value from the persistent object.

isUsingColumnName

public boolean isUsingColumnName()

Returns:

The UsingColumnName value

getColumnName

public java.lang.String getColumnName()

Returns:

The ColumnName value

checkConstraint

public abstract boolean checkConstraint(java.lang.Object dataField,
                                        java.lang.Object queryField)

Check to see if a given object passes this constraint.

Parameters:

dataField -

queryField -

Returns:

boolean: true iif the object dataField is acceptable by the rules of this constraint instance.

checkConstraint

public boolean checkConstraint(SQLQuery query,
                               Persistence poolElement,
                               java.lang.Object dataField,
                               java.lang.Object queryField)

Parameters:

query -

poolElement -

dataField -

queryField -

Returns:

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Publicize the clone method.

Overrides:

clone in class java.lang.Object

Returns:

Throws:

java.lang.CloneNotSupportedException

constructQueryString

public abstract java.lang.String constructQueryString()

Return the string which will appear in the query string. That is, what should follow the field specification? (ex, "NOT IN ('cat','dog')"). If this constraint is simply an operator, and the original comparison value should go on the RHS, then the last character should be a '*'. Ex, If the field is "quote.status", and the field' value has been specified to be "Q%", then returning "MATCHES*" will produce "quote.status MATCHES Q%". Ex, Using the above example, returning "NOT IN ('cat','dog')" will produce "quote.status NOT IN ('cat','dog')". Note that the returned string is never padded with spaces. Note that this method will return null if the string cannot be constructed for some reason (an messafe will already have been presented to the user. Perhaps I should delegate that responsability to the calling method... hmmm....)

Returns:

equals

public boolean equals(java.lang.Object obj)

A rudimentary but effective equals() method for subclasses of Constraint.

Overrides:

equals in class java.lang.Object

Parameters:

obj -

Returns:

findField

public boolean findField(java.lang.String field)

Parameters:

field -

Returns:

fromString

public abstract void fromString(java.lang.String str)
                         throws java.text.ParseException

Parse the string. Probably a string encoded via the toString() call, this method attempts to build the object's state from the information in string "str".

Parameters:

str -

Throws:

java.text.ParseException

staticListInsert

public abstract void staticListInsert(java.lang.String field)

Each type of constraint will have a specific set of fields associated with it. This is to allow the user to select them via Gui.

Parameters:

field -

stringify

public abstract java.lang.String stringify()

Stringify the object. Object serialization may be a better approach. Oh well. Encode the class's type and state in a readable string.

Returns:

toString

public java.lang.String toString()

toString returns the stringified object.

Overrides:

toString in class java.lang.Object

Returns:

formatString

protected java.lang.String formatString(java.lang.String input)
                                 throws java.lang.NoSuchFieldException,
                                        java.text.ParseException,
                                        java.lang.NumberFormatException

This is to abstract the need to get input in the correct format for a given field object, based on the class of the field indicated by getField() and getPersistence(). If either are null, or if the string getField() doesn't indicate a path to a real field, starting at the class of object getPersistence(), then a NoSuchFieldException is thrown. Otherwise, the method returns if 'input' is a recognizable format for the class indicated by getField(). If the input string is a bad format, then a ParseException is thrown. If the class indicated by getField() is not one of int, long, float, double, boolean, Integer, Long, Float, Double, Boolean, String, Date, or DateWithoutTime, then a just the input is returned. The returned is as a SQL-argument style version of the input.

Parameters:

input -

Returns:

Throws:

java.lang.NoSuchFieldException

java.text.ParseException

java.lang.NumberFormatException

stringToObject

protected java.lang.Object stringToObject(java.lang.String str,
                                          java.lang.Class classOfStr)

Parameters:

str - java.lang.String

classOfStr - java.lang.Class

Returns:

java.lang.Object