An XML data source uses an XML file to provide the data to print. The XML structure is not flat like a table, there are not rows and columns, it is more similar to a tree, where we can have several levels of data. We can say that all start from a root node, that can have any number of children. A child could be a value or another node with its children and so on. For this reason it is necessary to use an XPath query to identify which nodes of the XML document must be considered as records. The following XML is simple enough to easily explain how to do it:
Each record that we want to print can be identified with the XML node labeled "person". The selection of these specific xml tags is done with an XPath query like this: /addressbook/person XPath is a powerful query language to select data in an XML file. In this case the expression will select all the nodes of type "person" children of "addressbook". The result from the data source will be a set of three records (since the occurrences of the tag person child of addressbook are three). The goal is to write a report in Jaspersoft Studio with the list all the persons in the address book, showing for each person the name and the phone number..
Open Jaspersoft Studio and create a new report with "File->New->Jasper Report". In this example it is used a new report with the template select "Silhouette" and with file name "ContactXMLReport". Now you have to choose the data adapter, but since we don't have an adapter for the XML you have to click "New" and in the window that will appear select "XML document" and hit "Next".
In the next window insert the name of the new data adapter, for example "XMLAdapter", then hit the button "Browse" and select the XML file containing the data, select the option "Use the report Xpath expression when filling the report" to use an expression directlly inside the report. The difference from this two options is that the first use an expression defined into the report, so every report could use its own expression to retrive the data, the second one define an expression into the data adapter, so every report that will use that data adapter will is also its expression. When configuring an XML data source is possible to specify in which mode the data source must operate or to use and a Date and Number patterns that can be used to convert a text value in a more appropriate object (like a date or a number), since we don't need this simply click "Finish".
Now you will return to the report creation wizard and the data adapter just created should be selected, so you need to insert the XPath query, like we did with the SQL query in other tutorials. In this case JasperReports will execute the XPath query to select the nodes from the XML document provided using the XML data source. Infact every type of data adapter can provide an editor to interact with the data source (the XML in this case). For example for a JBDC data adapter we insert the SQL query and from this Jaspersoft Studio discovers the fields. With the XML you can provide an XPath query, like "/addressbook/person" but you can also compose it using a visual editor that show the tree structure of the the XML and you can browse the nodes. By double clicking on a node the XPath query will be automatically generated. The advantage of keeping the XPath query inside the report is that we can use parameters to make the query dynamic.
Note that the query "/addressbook/person" returns all the people under the tag "addressbook", and as fields there are the children nodes of person, so name and phone. Now you can click next and as announced the fields "name" and "phone" were discovered. Add them to the report with the button ">>" and then hit "Next".
We don't need groups so on the next step select "Next" and then "Finish". Now the report will be created and if you switch in the "Preview" mode you should see this result:
