<message> tag element helps to debug an XSLT processing. It is similar to javascript alerts. <xsl:> tag buffers a message to XSLT processor which terminates the processing and sends a message to the caller application to display the error message.
Declaration
Following is the syntax declaration of <xsl:message> element.
<xsl:message terminate = "yes" | "no" > </xsl:message>
Attributes
| Sr.No | Name & Description |
|---|---|
| 1 | terminateIt specifies whether the transformation should terminate upon executing this instruction or not. Default is “yes”. |
Elements
| Number of Occurrences | Unlimited |
|---|---|
| Parent elements | xsl:attribute, xsl:comment, xsl:copy, xsl:element, xsl:fallback, xsl:foreach, xsl:if, xsl:message, xsl:otherwise, xsl:param, xsl:processinginstruction, xsl:template, xsl:variable, xsl:when, xsl:with-param, output elements |
| Child elements | xsl:apply-templates, xsl:attribute, xsl:call-template, xsl:choose, xsl:comment, xsl:copy, xsl:copy-of, xsl:element, xsl:for-each, xsl:if, xsl:processing-instruction, xsl:text, xsl:value-of, xsl:variable, output elements |
Demo Example
This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student. It checks key as firstname to be present and then prints the student details, otherwise displays an error message.
students.xml
<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
<student rollno = "393">
<firstname>Dinkar</firstname>
<lastname>Kad</lastname>
<nickname>Dinkar</nickname>
<marks>85</marks>
</student>
<student rollno = "493">
<firstname></firstname>
<lastname>Gupta</lastname>
<nickname>Vinni</nickname>
<marks>95</marks>
</student>
<student rollno = "593">
<firstname>Jasvir</firstname>
<lastname>Singh</lastname>
<nickname>Jazz</nickname>
<marks>90</marks>
</student>
</class>
students.xsl
<?xml version = "1.0" encoding = "UTF-8"?>
<xsl:stylesheet version = "1.0"
xmlns:xsl = "http://www.w3.org/1999/XSL/Transform">
<xsl:template match = "/">
<html>
<body>
<h2>Students</h2>
<table border = "1">
<tr bgcolor = "#9acd32">
<th>Roll No</th>
<th>First Name</th>
<th>Last Name</th>
<th>Nick Name</th>
<th>Marks</th>
</tr>
<xsl:for-each select = "class/student">
<xsl:if test = "firstname = ''">
<xsl:message terminate = "yes">A first name field is empty.
</xsl:message>
</xsl:if>
<tr>
<td><xsl:value-of select = "@rollno"/></td>
<td><xsl:value-of select = "firstname"/></td>
<td><xsl:value-of select = "lastname"/></td>
<td><xsl:value-of select = "nickname"/></td>
<td><xsl:value-of select = "marks"/></td>
</tr>
</xsl:for-each>
</table>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
Output
