XML Validation with XSLT & Calling Custom function from XSLT
I will discuss about validating XML against defined XSL. Prior to getting into this article it’s mandatory that one should have basic knowledge on what is XML & XSL.
This example describes below business rules:
1. If UserName, Password node not exists, generate XML ERROR as output
2. If UserName, Password nodes are empty, generate XML ERROR as output
3. Check if user,password exists in DB or not & generate XML SUCCESS or ERROR as output
In this article, I will discuss about validating XML against defined XSL. Prior to getting into this article it's mandatory that one should have basic knowledge on what is XML & XSL.
Considering below XML as input (UserCheck.xml) to our application
<?xml version="1.0? encoding="utf-16??>
<root xmlns:func="urn:actl-xslt">
<User>
<UserName>suryaprakash</UserName>
<Password>password</Password>
</User>
</root>
This example describes below business rules:
1. If UserName, Password node not exists, generate XML ERROR as output
2. If UserName, Password nodes are empty, generate XML ERROR as output
3. Check if user,password exists in DB or not & generate XML SUCCESS or ERROR as output
The output would be as follows if any errors, which will be inserted into XML file (result.xml)
Each ERROR tag would represent each error with ERRORMSG & ERRORCODE
<root xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:func="urn:actl-xslt">
<OUTPUT>
<ERROR>
<ErrorMsg>
UserName Node Contains Invalid Data
</ErrorMsg>
<ErrorCode>
ERR_003
</ErrorCode>
</ERROR>
</OUTPUT>
</root>
Let get into sample with below steps
1. Step 1: Define XML
2. Step 2: Define XSL as per our business rules defined above
3. Step 3: Define function which will be called from XSL
4. Step 4: Implement code validate XML with XSL as follows which will be called from XSL
Step 1: Define XML
Considering below XML as input to our example
<?xml version="1.0? encoding="utf-16??>
<root xmlns:func="urn:actl-xslt">
<User>
<UserName>suryaprakash</UserName>
<Password>password</Password>
</User>
</root>
Step 2: Define XSL as per our business rules defined above
<?xml version="1.0??>
<xsl:stylesheet
version="1.0?
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
xmlns:func="urn:actl-xslt">
<xsl:template match="root">
<root>
<xsl:for-each select="User">
<OUTPUT>
<xsl:if test="not(UserName)">
<ERROR>
<ErrorMsg>
UserName Node not present
</ErrorMsg>
<ErrorCode>
ERR_001
</ErrorCode>
</ERROR>
</xsl:if>
<xsl:if test="not(Password)">
<ERROR>
<ErrorMsg>
Password Node not present
</ErrorMsg>
<ErrorCode>
ERR_002
</ErrorCode>
</ERROR>
</xsl:if>
<xsl:if test="UserName="">
<ERROR>
<ErrorMsg>
UserName Node Contains Invalid Data
</ErrorMsg>
<ErrorCode>
ERR_003
</ErrorCode>
</ERROR>
</xsl:if>
<xsl:if test="Password="">
<ERROR>
<ErrorMsg>
Password Node Contains Invalid Data
</ErrorMsg>
<ErrorCode>
ERR_004
</ErrorCode>
</ERROR>
</xsl:if>
<xsl:value-of select="func:checkUserExist('UserName','Password')" />
</OUTPUT>
</xsl:for-each>
</root>
</xsl:template>
</xsl:stylesheet>
For above XSL below are code comments
Code Comment #1
xmlns:func="urn:actl-xslt"
Note the attribute that I have added here as - xmlns:func="urn:actl-xslt"
Code Comment #2
The prefix added to my external method
func:checkUserExist('UserName','Password') as below
<xsl:value-of select="func:checkUserExist('UserName','Password')" />
Code Comment #3
<xsl:if test="not(UserName)">
This tag is used to check if USERNAME node exists or not
Code Comment #4
<xsl:if test="UserName="">
This tag is used to check if content in USERNAME node is empty or not
Step 3: Define function which will be called from XSL
This function will be called from XSL defined as
<xsl:value-of select="func:checkUserExist('UserName','Password')" />
Instead of checking username against DB we are checking with static value. If username matches it return Success string else it would return ErrorStrings
public string checkUserExist(string uName, string pWord)
{
string returnValue = string.Empty;
if (uName == "prakash")
{
returnValue = "
}
else
{
returnValue = "
}
return returnValue;
}
Step 4: Implement code validate XML with XSL as follows which will be called from XSL.
This below function will be called in main method & this function declare 3 main variables for XML input, XSL input & XML output as result.xml
public void CheckUserXslt()
{
string sourceDoc = @"D:\Surya Prakash\WorkAround\GopalSample\XML\CheckUser.XML";
string xsltDoc = @"D:\Surya Prakash\WorkAround\GopalSample\XML\CheckUser.xslt";
string resultDoc = @"D:\Surya Prakash\WorkAround\GopalSample\XML\result.xml";
XsltArgumentList xsltArguments = null;
XsltExtension xsltExtension = new XsltExtension();
xsltArguments = new XsltArgumentList();
xsltArguments.AddExtensionObject("urn:actl-xslt", xsltExtension);
XPathDocument myXPathDocument = new XPathDocument(sourceDoc);
XslTransform myXslTransform = new XslTransform();
XmlTextWriter writer = new XmlTextWriter(resultDoc, null);
myXslTransform.Load(xsltDoc);
myXslTransform.Transform(myXPathDocument, xsltArguments, writer);
writer.Close();
StreamReader stream = new StreamReader(resultDoc);
}
Finally run the application by modifying the input XML & see the output in result.xml
Happy Kooding… Hope this helps!