org.mmbase.core
Class AbstractField

java.lang.Object
  org.mmbase.core.AbstractDescriptor
      org.mmbase.core.AbstractField

All Implemented Interfaces:

Cloneable, Comparable, Descriptor, Field

Direct Known Subclasses:

BasicField, CoreField

public abstract class AbstractField

extends AbstractDescriptor

implements Field, Comparable

Since:

MMBase-1.8

Version:

$Id: AbstractField.java,v 1.13 2006/06/26 11:45:50 michiel Exp $

Author:

Pierre van Rooden, Michiel Meeuwissen

Warning: No Java Documentation Available.

Field Summary

protected DataType	dataType
protected int	listItemType
protected boolean	readOnly
protected int	state
protected int	type

Fields inherited from class org.mmbase.core.AbstractDescriptor

description, guiName, key

Fields inherited from interface org.mmbase.bridge.Field

STATE_PERSISTENT, STATE_SYSTEM, STATE_SYSTEM_VIRTUAL, STATE_UNKNOWN, STATE_VIRTUAL, TYPE_BINARY, TYPE_BOOLEAN, TYPE_BYTE, TYPE_DATETIME, TYPE_DOUBLE, TYPE_FLOAT, TYPE_INTEGER, TYPE_LIST, TYPE_LONG, TYPE_NODE, TYPE_STRING, TYPE_UNKNOWN, TYPE_XML

Constructor Summary

protected	AbstractField(String name, Field field) Create a field object based on another field.
protected	AbstractField(String name, Field field, boolean cloneDataForRewrite) Create a field object based on another field.
protected	AbstractField(String name, int type, int listItemType, int state, DataType dataType) Create a field object

Method Summary

Object	clone()
Object	clone(String name, boolean copyDataTypeForRewrite)
int	compareTo(Object o)
boolean	equals(Object o) Whether data type equals to other data type.
DataType	getDataType() Returns the data type this field contains.
abstract int	getEditPosition() Retrieve the position of the field when editing.
abstract String	getGUIType() Returns the GUI name for the data type this field contains.
int	getListItemType() If the type of this field is TYPE_LIST, this method returns the MMBase base type for the list elements.
abstract int	getListPosition() Retrieve the position of the field when listing.
abstract int	getMaxLength() Returns the maximum length of data this field can contain.
abstract NodeManager	getNodeManager() Returns the node manager this field belongs to.
abstract int	getSearchPosition() Retrieve the position of the field when searching.
int	getState() Returns this field's state identifier (virtual, persistent, system, systemvirtual).
abstract int	getStoragePosition() Retrieve the position of the field in the database table.
int	getType() Returns the identifier for the MMBase base type for this field.
int	hashCode()
boolean	hasIndex() Returns whether this field is a key field, meaning that the storage layer should define an index for it, allowing optimization with search and sort actions.
boolean	isReadOnly() Returns whether a field is 'read only' - that is, a user cannot edit it.
boolean	isRequired() Returns whether this field is required (should have content).
boolean	isTemporary() Returns whether a field is a temporary field.
boolean	isUnique() Retrieve whether the field is a key and thus need be unique.
boolean	isVirtual() A field's state is 'virtual' if it is not persistent in storage.
void	setDataType(DataType dataType) Sets the datatype of a field.
protected void	setState(int state)
String	toString() Returns a description for this field.

Methods inherited from class org.mmbase.core.AbstractDescriptor

clone, getDefaultLocale, getDescription, getDescription, getGUIName, getGUIName, getLocalizedDescription, getLocalizedGUIName, getName, setDescription, setDescription, setGUIName, setGUIName, setLocalizedDescription, setLocalizedGUIName

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.mmbase.bridge.Field

validate

Methods inherited from interface org.mmbase.bridge.Descriptor

getDescription, getDescription, getGUIName, getGUIName, getLocalizedDescription, getLocalizedGUIName, getName, setDescription, setDescription, setGUIName, setGUIName

Field Detail

dataType

protected DataType dataType

type

protected int type

state

protected int state

listItemType

protected int listItemType

readOnly

protected boolean readOnly

Constructor Detail

AbstractField

protected AbstractField(String name,
                        Field field)

Create a field object based on another field. The newly created field shared the datatype of it's parent (which means that any changes to the datatype affects both fields).

Parameters:

name - the name of the field

field - the parent field

AbstractField

protected AbstractField(String name,
                        Field field,
                        boolean cloneDataForRewrite)

Create a field object based on another field.

Parameters:

name - the name of the field

field - the parent field

cloneDataForRewrite - determines whether the datatype of the parent field is copied (which means it can be altered without affecting the original datatype)

AbstractField

protected AbstractField(String name,
                        int type,
                        int listItemType,
                        int state,
                        DataType dataType)

Create a field object

Parameters:

name - the name of the field

dataType - the data type of the field

Method Detail

getNodeManager

public abstract NodeManager getNodeManager()

Description copied from interface: Field

Returns the node manager this field belongs to.

Specified by:

getNodeManager in interface Field

Returns:

the node manager this field belongs to

compareTo

public int compareTo(Object o)

Specified by:

compareTo in interface Comparable

equals

public boolean equals(Object o)

Whether data type equals to other data type. Only key and type are considered. DefaultValue and required propererties are only 'utilities'.

Returns:

true if o is a DataType of which key and type equal to this' key and type.

hashCode

public int hashCode()

getState

public int getState()

Description copied from interface: Field

Returns this field's state identifier (virtual, persistent, system, systemvirtual).

Specified by:

getState in interface Field

Returns:

an int which identifies the state of this field

setState

protected void setState(int state)

getType

public int getType()

Description copied from interface: Field

Returns the identifier for the MMBase base type for this field. This represents one of field type constants. This basic type determines how data is stored in MMBase. Note that it is possible that the datatype for a field (used for validation and in/out put) can be of a different basic type than how it is stored in the database. This shoudl not occur often, but is possible in some cases, such as when you use older clod models (which used INTEGER fields for dates). In general this should not prove a [problem - however you shoudl not assumeto know the classtype iof data of a field based on this method. To acquire the datatype's type, use getDataType.getBaseType() instead.

Specified by:

getType in interface Field

Returns:

an int which identifies the base type

getListItemType

public int getListItemType()

Description copied from interface: Field

If the type of this field is TYPE_LIST, this method returns the MMBase base type for the list elements. This represents one of field type constants. This basic type determines how data is stored in MMBase. For any field types other that TYPE_LIST, this method returns TYPE_UNKNOWN.

Specified by:

getListItemType in interface Field

Returns:

an int which identifies the base type

getDataType

public DataType getDataType()

Description copied from interface: Field

Returns the data type this field contains.

Specified by:

getDataType in interface Field

Returns:

a DataType object describing the constraints on this field.

setDataType

public void setDataType(DataType dataType)
                 throws IllegalArgumentException

Sets the datatype of a field. It is possible that the datatype of a field is different from the actual field type.

Throws:

IllegalArgumentException

See Also:

getType()

hasIndex

public boolean hasIndex()

Description copied from interface: Field

Returns whether this field is a key field, meaning that the storage layer should define an index for it, allowing optimization with search and sort actions. Note that MMBase lets the storage layer decide whether an index is actually defined. Some implementations or configurations may not do this. Note: Currently, this method only returns true if the field is the primary key (number field) or a Node field.

Specified by:

hasIndex in interface Field

Returns:

true if the field has a key defined

getSearchPosition

public abstract int getSearchPosition()

Description copied from interface: Field

Retrieve the position of the field when searching. A value of -1 indicates the field is unavailable during search.

Specified by:

getSearchPosition in interface Field

getListPosition

public abstract int getListPosition()

Description copied from interface: Field

Retrieve the position of the field when listing. A value of -1 indicates the field is unavailable in a list.

Specified by:

getListPosition in interface Field

getEditPosition

public abstract int getEditPosition()

Description copied from interface: Field

Retrieve the position of the field when editing. A value of -1 indicates the field cannot be edited.

Specified by:

getEditPosition in interface Field

getStoragePosition

public abstract int getStoragePosition()

Description copied from interface: Field

Retrieve the position of the field in the database table.

Specified by:

getStoragePosition in interface Field

isUnique

public boolean isUnique()

Retrieve whether the field is a key and thus need be unique.

Specified by:

isUnique in interface Field

Returns:

true if the field is part of a unique key

getMaxLength

public abstract int getMaxLength()

Description copied from interface: Field

Returns the maximum length of data this field can contain. For example if a field contains characters the size indicates the maximum number of characters it can contain. If the field is a numeric field (such as an integer), the result is -1.

Specified by:

getMaxLength in interface Field

Returns:

the maximum length of data this field can contain

isRequired

public boolean isRequired()

Description copied from interface: Field

Returns whether this field is required (should have content). Note that MMBase does not generally enforce required fields to be filled - If not provided, a default value (generally an empty string or the integer value -1) is filled in by the system. As such, isRequired will mostly be used as an indicator for (generic) editors.

Specified by:

isRequired in interface Field

Returns:

true if the field is required

See Also:

Field.isRequired()

isVirtual

public boolean isVirtual()

Description copied from interface: Field

A field's state is 'virtual' if it is not persistent in storage.

Specified by:

isVirtual in interface Field

Returns:

true when a field is virtual

See Also:

Field.isVirtual()

isTemporary

public boolean isTemporary()

Returns whether a field is a temporary field. Temporary fields hold data needed by a builder to facilitate certain functionality, such as holding node references in a transaction. Temporary fields are never persistent and should normally be ignored.

Since:

MMBase-1.8

isReadOnly

public boolean isReadOnly()

Description copied from interface: Field

Returns whether a field is 'read only' - that is, a user cannot edit it. In general, fields with state SYSTEM or SYSTEM_VIRTUAL are defined as read only, while others are not. It is possible to override this behaviour per field.

Specified by:

isReadOnly in interface Field

Returns:

true when a field is read only

See Also:

Field.isVirtual()

getGUIType

public abstract String getGUIType()

Description copied from interface: Field

Returns the GUI name for the data type this field contains.

Specified by:

getGUIType in interface Field

See Also:

Field.getDataType()

toString

public String toString()

Returns a description for this field.

Overrides:

toString in class AbstractDescriptor

clone

public Object clone()

Overrides:

clone in class AbstractDescriptor

clone

public Object clone(String name,
                    boolean copyDataTypeForRewrite)