com.allanbank.mongodb.bson.element

Class NullElement

java.lang.Object

com.allanbank.mongodb.bson.element.AbstractElement

com.allanbank.mongodb.bson.element.NullElement

All Implemented Interfaces:

Element, ElementAssignable, Serializable, Comparable<Element>

public class NullElement
extends AbstractElement

A wrapper for a BSON null.

See Also:

Serialized Form

API Notice:

This class is part of the driver's API. Public and protected members will be deprecated for at least 1 non-bugfix release (version numbers are <major>.<minor>.<bugfix>) before being removed or modified.

Copyright ©:

2011-2013, Allanbank Consulting, Inc., All Rights Reserved

Field Summary

Fields

Modifier and Type	Field and Description
static ElementType	TYPE The BSON type for a binary.

Fields inherited from class com.allanbank.mongodb.bson.element.AbstractElement

ELEMENT_TYPE

Constructor Summary

Constructors

Constructor and Description
NullElement(String name) Constructs a new NullElement.
NullElement(String name, long size) Constructs a new NullElement.

Method Summary

Methods

Modifier and Type	Method and Description
void	accept(Visitor visitor) Accepts the visitor and calls the Visitor.visitNull(java.lang.String) method.
ElementType	getType() Returns the type for the BSON type.
Object	getValueAsObject() Returns the value for BSON element as a Java Object type.
String	getValueAsString() Returns the value for BSON element as a Java String.
NullElement	withName(String name) Creates a new element with the same type and value as this element but with the specified name.

Methods inherited from class com.allanbank.mongodb.bson.element.AbstractElement

asElement, compareTo, equals, find, find, findFirst, findFirst, getName, hashCode, nullSafeEquals, size, toString

Methods inherited from class java.lang.Object

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

Field Detail

TYPE

public static final ElementType TYPE

The BSON type for a binary.

Constructor Detail

NullElement

public NullElement(String name)

Constructs a new NullElement.

Parameters:

name - The name for the BSON null.

Throws:

IllegalArgumentException - If the name is null.

NullElement

public NullElement(String name,
           long size)

Constructs a new NullElement.

Parameters:

name - The name for the BSON null.

size - The size of the element when encoded in bytes. If not known then use the NullElement(String) constructor instead.

Throws:

IllegalArgumentException - If the name is null.

Method Detail

accept

public void accept(Visitor visitor)

Accepts the visitor and calls the Visitor.visitNull(java.lang.String) method.

Parameters:

visitor - The visitor for the element.

See Also:

Element.accept(Visitor)

getType

public ElementType getType()

Returns the type for the BSON type.

Returns:

The type for the BSON type.

getValueAsObject

public Object getValueAsObject()

Returns the value for BSON element as a Java Object type.

Automatic conversion from the Object-ified value to an element is provided via the DocumentBuilder.add(String, Object) method. Not all element types will be successfully converted to the same element duing a Element-->Object value-->Element conversion. This cases are noted in the appropriate sub-type's JavaDoc.

Sub-types will also overload this method with the appropriate type returned. e.g., The StringElement.getValueAsObject() method signature returns a String.

Returns null.

Returns:

The value for BSON element as a Java Object type.

getValueAsString

public String getValueAsString()

Returns the value for BSON element as a Java String. Automatic conversion from the string value back to an Element is not provided.

Generally the string returned will be the expected value. As an example for a LongElement with the value 101 the returned string will be "101". In those cases where there is not canonical form for the value (e.g., a TimestampElement the returned string will match the value when converted to JSON by the JsonSerializationVisitor. For a TimestampElement that is a string of the form "ISODate('1970-01-01T00:00:00.000+0000')".

Uses the JsonSerializationVisitor to encode the value. In some cases it will be more efficient to override this method with a more straight forward conversion.

Returns the result of String.valueOf(null) .

Specified by:

getValueAsString in interface Element

Overrides:

getValueAsString in class AbstractElement

Returns:

The value for BSON element as a String.

withName

public NullElement withName(String name)

Creates a new element with the same type and value as this element but with the specified name. This is useful when creating a query across a set of collections where the filed name changes in the collections but the values must be identical.

Returns a new NullElement.

Parameters:

name - The new name for the element.

Returns:

The created element.