net.sf.jasperreports.engine.data

Class AbstractXmlDataSource<T extends AbstractXmlDataSource<?>>

java.lang.Object

net.sf.jasperreports.engine.data.JRAbstractTextDataSource

net.sf.jasperreports.engine.data.AbstractXmlDataSource<T>

All Implemented Interfaces:

JRDataSource, JRRewindableDataSource

Direct Known Subclasses:

JaxenXmlDataSource, JRXmlDataSource, XalanXmlDataSource

public abstract class AbstractXmlDataSource<T extends AbstractXmlDataSource<?>>
extends JRAbstractTextDataSource
implements JRRewindableDataSource

Abstract XML data source implementation that allows to access the data from a xml document using XPath expressions.

The data source is constructed around a node set (record set) selected by an XPath expression from the xml document.

Each field can provide an additional XPath expression that will be used to select its value. This expression must be specified using the PROPERTY_FIELD_EXPRESSION custom property at field level. The use of the field description to specify the XPath expression is still supported, but is now discouraged, the above mentioned custom property taking precedence over the field description. In case no XPath expression is specified, the name of the field will be used for the selection of the value. The expression is evaluated in the context of the current node thus the expression should be relative to the current node.

To support subreports, sub data sources can be created. There are two different methods for creating sub data sources. The first one allows to create a sub data source rooted at the current node. The current node can be seen as a new document around which the sub data source is created. The second method allows to create a sub data source that is rooted at the same document that is used by the data source but uses a different XPath select expression.

Example:

 <A>
        <B id="0">
                <C>
                <C>
        </B>
        <B id="1">
                <C>
                <C>
        </B>
        <D id="3">
                <E>
                <E>
        </D>
 </A>
 

Data source creation

• new JRXmlDataSource(document, "/A/B") - creates a data source with two nodes of type /A/B
• new JRXmlDataSource(document, "/A/D") - creates a data source with two nodes of type /A/D

Field selection

• @id - will select the "id" attribute from the current node
• C - will select the value of the first node of type C under the current node.

Sub data source creation

• "((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("/B/C") - in the context of the node B, creates a data source with elements of type /B/C
• "((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).dataSource("/A/D") - creates a data source with elements of type /A/D

Generally the full power of XPath expression is available. As an example, "/A/B[@id > 0"] will select all the nodes of type /A/B having the id greater than 0. You'll find a short XPath tutorial here.

Note on performance. Due to the fact that all the XPath expression are interpreted the data source performance is not great. For the cases where more speed is required, consider implementing a custom data source that directly accesses the Document through the DOM API.

Author:

Narcis Marcu (narcism@users.sourceforge.net)

Field Summary

Fields

Modifier and Type	Field and Description
static String	PROPERTY_FIELD_EXPRESSION Property specifying the XPath expression for the dataset field.

Fields inherited from class net.sf.jasperreports.engine.data.JRAbstractTextDataSource

EXCEPTION_MESSAGE_KEY_CANNOT_CONVERT_FIELD_TYPE, EXCEPTION_MESSAGE_KEY_CANNOT_MODIFY_PROPERTIES_AFTER_START, EXCEPTION_MESSAGE_KEY_NODE_NOT_AVAILABLE, EXCEPTION_MESSAGE_KEY_NULL_DOCUMENT, EXCEPTION_MESSAGE_KEY_NULL_SELECT_EXPRESSION, EXCEPTION_MESSAGE_KEY_UNKNOWN_COLUMN_NAME, EXCEPTION_MESSAGE_KEY_UNKNOWN_NUMBER_TYPE

Constructor Summary

Constructors

Constructor and Description
AbstractXmlDataSource()

Method Summary

Methods

Modifier and Type	Method and Description
T	dataSource() Creates a sub data source using as root document the document used by "this" data source.
abstract T	dataSource(String selectExpr) Creates a sub data source using as root document the document used by "this" data source.
abstract Node	getCurrentNode()
protected String	getFieldExpression(JRField field)
Object	getFieldValue(JRField jrField) Gets the field value for the current position.
abstract Object	getSelectObject(Node currentNode, String expression)
String	getText(Node node) Return the text that a node contains.
T	subDataSource() Creates a sub data source using the current node (record) as the root of the document.
abstract T	subDataSource(String selectExpr) Creates a sub data source using the current node (record) as the root of the document.
abstract Document	subDocument() Creates a document using the current node as root.

Methods inherited from class net.sf.jasperreports.engine.data.JRAbstractTextDataSource

convertNumber, convertStringValue, getConvertBean, getDatePattern, getFormattedDate, getFormattedNumber, getLocale, getNumberPattern, getTextAttributes, getTimeZone, setDatePattern, setLocale, setLocale, setNumberPattern, setTextAttributes, setTextAttributes, setTimeZone, setTimeZone

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.jasperreports.engine.JRRewindableDataSource

moveFirst

Methods inherited from interface net.sf.jasperreports.engine.JRDataSource

next

Field Detail

PROPERTY_FIELD_EXPRESSION

public static final String PROPERTY_FIELD_EXPRESSION

Property specifying the XPath expression for the dataset field.

See Also:

Constant Field Values

Constructor Detail

AbstractXmlDataSource

public AbstractXmlDataSource()

Method Detail

getCurrentNode

public abstract Node getCurrentNode()

getSelectObject

public abstract Object getSelectObject(Node currentNode,
                     String expression)
                                throws JRException

Throws:

JRException

getFieldValue

public Object getFieldValue(JRField jrField)
                     throws JRException

Description copied from interface: JRDataSource

Gets the field value for the current position.

Specified by:

getFieldValue in interface JRDataSource

Returns:

an object containing the field value. The object type must be the field object type.

Throws:

JRException

subDataSource

public abstract T subDataSource(String selectExpr)
                                                          throws JRException

Creates a sub data source using the current node (record) as the root of the document. An additional XPath expression specifies the select criteria applied to this new document and that produces the nodes (records) for the data source.

Parameters:

selectExpr - the XPath select expression

Returns:

the xml sub data source

Throws:

JRException - if the sub data source couldn't be created

See Also:

JRXmlDataSource.JRXmlDataSource(Document, String)

subDataSource

public T subDataSource()
                                                 throws JRException

Creates a sub data source using the current node (record) as the root of the document. The data source will contain exactly one record consisting of the document node itself.

Returns:

the xml sub data source

Throws:

JRException - if the data source cannot be created

See Also:

JRXmlDataSource.subDataSource(String), JRXmlDataSource.JRXmlDataSource(Document)

subDocument

public abstract Document subDocument()
                              throws JRException

Creates a document using the current node as root.

Returns:

a document having the current node as root

Throws:

JRException

dataSource

public abstract T dataSource(String selectExpr)
                                                       throws JRException

Creates a sub data source using as root document the document used by "this" data source. An additional XPath expression specifies the select criteria applied to this document and that produces the nodes (records) for the data source.

Parameters:

selectExpr - the XPath select expression

Returns:

the xml sub data source

Throws:

JRException - if the sub data source couldn't be created

See Also:

JRXmlDataSource.JRXmlDataSource(Document, String)

dataSource

public T dataSource()
                                              throws JRException

Creates a sub data source using as root document the document used by "this" data source. The data source will contain exactly one record consisting of the document node itself.

Returns:

the xml sub data source

Throws:

JRException - if the data source cannot be created

See Also:

JRXmlDataSource.dataSource(String), JRXmlDataSource.JRXmlDataSource(Document)

getText

public String getText(Node node)

Return the text that a node contains. This routine:

• Ignores comments and processing instructions.
• Concatenates TEXT nodes, CDATA nodes, and the results of recursively processing EntityRef nodes.
• Ignores any element nodes in the sublist. (Other possible options are to recurse into element sublists or throw an exception.)

Parameters:

node - a DOM node

Returns:

a String representing node contents or null

getFieldExpression

protected String getFieldExpression(JRField field)