Class AbstractXmlDataSource<T extends AbstractXmlDataSource<?>>
- All Implemented Interfaces:
HierarchicalDataSource<T>
,RandomAccessDataSource
,JRDataSource
,JRRewindableDataSource
- Direct Known Subclasses:
JaxenXmlDataSource
,JRXmlDataSource
,XalanXmlDataSource
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
- @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.
- "((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)
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final String
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
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionCreates 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
Access the document that this data source is based on.protected String
getFieldExpression
(JRField field) getFieldValue
(JRField jrField) Gets the field value for the current position.abstract Object
getSelectObject
(Node currentNode, String expression) Return the text that a node contains.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
Creates a document using the current node as root.Methods inherited from class net.sf.jasperreports.engine.data.JRAbstractTextDataSource
convertNumber, convertStringValue, getConvertBean, getDatePattern, 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.JRDataSource
next
Methods inherited from interface net.sf.jasperreports.engine.JRRewindableDataSource
moveFirst
Methods inherited from interface net.sf.jasperreports.engine.data.RandomAccessDataSource
currentIndex, moveToRecord, recordCount
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Field Details
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PROPERTY_FIELD_EXPRESSION
Property specifying the XPath expression for the dataset field.- See Also:
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Constructor Details
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AbstractXmlDataSource
public AbstractXmlDataSource()
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Method Details
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getDocument
Access the document that this data source is based on.- Returns:
- the document used by this data source
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getCurrentNode
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getSelectObject
- Throws:
JRException
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getFieldValue
Description copied from interface:JRDataSource
Gets the field value for the current position.- Specified by:
getFieldValue
in interfaceJRDataSource
- Returns:
- an object containing the field value. The object type must be the field object type.
- Throws:
JRException
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subDataSource
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.- Specified by:
subDataSource
in interfaceHierarchicalDataSource<T extends AbstractXmlDataSource<?>>
- 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:
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subDataSource
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.- Specified by:
subDataSource
in interfaceHierarchicalDataSource<T extends AbstractXmlDataSource<?>>
- Returns:
- the xml sub data source
- Throws:
JRException
- if the data source cannot be created- See Also:
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subDocument
Creates a document using the current node as root.- Returns:
- a document having the current node as root
- Throws:
JRException
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dataSource
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:
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dataSource
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:
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getText
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
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getFieldExpression
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