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Accessing XML Data From XML Document In C# Console Application

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In this article, I am going to give you the best way to access XML data from an XML document and also how to find the common record node count.

Students.xml

  1. <Data>  
  2.     <Student Name="Saravanan"// Node with same name  
  3.   
  4.   
  5.         <Address>Address1</Address>  
  6.         <SurName> SurName1  
  7.         </ SurName>  
  8.         <City>City1</City>  
  9.         <State>State1</State>  
  10.     </Student>  
  11.     <Student Name="Mohan">  
  12.         <SurName> SurName2  
  13.         </ SurName>  
  14.         <Address>Address2</Address>  
  15.         <City>City2</City>  
  16.         <State>State2</State>  
  17.     </Student>  
  18.     <Student Name="Fayaz">  
  19.         <SurName> SurName3  
  20.         </ SurName>  
  21.         <Address>Address3</Address>  
  22.         <City>City3</City>  
  23.         <State>State3</State>  
  24.     </Student>  
  25.     <Student Name="Siva">  
  26.         <SurName> SurName4  
  27.         </ SurName>  
  28.         <Address>Address4</Address>  
  29.         <City>City4</City>  
  30.         <State>State4</State>  
  31.     </Student>  
  32.     <Student Name="Saravanan"// Node with same name  
  33.   
  34.   
  35.         <Address>Address5</Address>  
  36.         <SurName> SurName5  
  37.         </ SurName>  
  38.         <City>City5</City>  
  39.         <State>State5</State>  
  40.     </Student>  
  41. </Data>  

Step 1

Before we do anything with the XML document, we have to first load the XML file. The following code is the common way to load a XML document.

Note

Before dealing with XML, initilize the XML Namespace, i.e., using system.xml;

  1. XMLDocument  StudentDocument = new xmlDocument();  
  2. studentDocument("give the XML Documnet Path here e.g C://Studentrecords/Student.xml");  

Step 2

Now, we are going to access the XML data from XML document by using XPath.

XPath

XPath is used to navigate through elements and attributes in an XML document. In other words, XPath uses the path expressions to select nodes or node-sets in an XML Document.

Here is the code:

By using XmlNode keyword, we can access the node value.

 

  1. XmlNode Singlenode=StudentDocument.SelectSingleNode("XPath here E.g /Data/Students/Student[@ Name='Mohan']/Address "); // accessing one student record  

Note

Still, the data is in XML format. So we assign the node value to another string variable so that the value can be used for further purpose.

 

  1. string StudentAddress= Singlenode.InnerText;  

Now, consider the situation of needing to get the correct data from XML document if two students have the same name. Then, by comparing the surname, we can get the correct data. Try the following code.

Note

Consider the above XML document. It has two nodes with the same name "Saravanan".

  1. <Student Name="Saravanan"// Node with same name  
  2.     <Address>Address1</Address>  
  3.     <SurName> SurName1</ SurName>  
  4.         <City>City1</City>  
  5.         <State>State1</State>  
  6. </Student>  
  7. <Student Name="Saravanan"// Node with same name  
  8.     <Address>Address5</Address>  
  9.     <SurName> SurName5</ SurName>  
  10.         <City>City5</City>  
  11.         <State>State5</State>  
  12. </Student>  

Eg

User input is---- Student Name - Saravanan and SurName-SurName5

To find the number of nodes with the same value, try the following code.

 

  1. XmlNodeList Lists = Students.SelectNodes(" /Data/Students/Student[@ Name='Saravanan']/Address ");  

Note: For getting a single node value, we use "XmlNode" Keyword, but for finding more than one nodes with the same value, we have to use "XmlNodeList".

  1. if (Lists.count > 1) {  
  2.     //if this loop is executes ,mean there is morethan one node with same value  
  3.     foreach(XmlNode List in Lists) {  
  4.         //this loop is for comparing the surname to get correct node value  
  5.         SingleNodeSurName = StudentDocument.SelectSingleNode("XPath here E.g /Data/Students/Student[@ Name='Mohan']/SurName ").InnerText;  
  6.         //Now compare the Address with user input address  
  7.         if (SingleNodeSurName.toUpper() == UserInputSurName.toUpper()) {  
  8.             //if two Surname is same it get all other data's by the same above method  
  9.             Address,  
  10.             City,  
  11.             State  
  12.         }  
  13.     }  
  14. }  

I hope this article is very useful. Thank You.

posted Jan 10 by Shivaranjini

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This article describes how to transform the XML output of SQL query statements using FOR XML AUTO to HTML using XSLT.

Normally, we execute the query using ExecuteNonQuery statement and fill the output into a data table. We can access the data in the data table by giving column name and row number in the looping method. This makes us work on extra coding and takes a lot of time to get the correct data from executed query. So, I moved to XML because, in XML, we can fetch the values easily and quickly without writing too much code.     

FOR XML Clause in SQL

Basically, we have four types of FOR XML clause in SQL.

  • FOR XML RAW
  • FOR XML AUTO
  • FOR XML EXPLICIT
  • FOR XML PATH

Each of the above types satisfies its own need. When you want full control over the produced XML, you use FOR XML EXPLICIT, but it is difficult to understand, read, or maintain. FOR XML AUTO produces the most readable SELECT statement. The RAW option is rarely used and therefore not discussed. The PATH option allows you to mix attributes and elements easier. Here, I gona use FOR XML AUTO.

Table Name - Contact_Details

Contact_IDContact_NumberContact_NameContact_Location
001088888888MohanChennnai
002099999999AbilashBangalore


If we want the output as in XML format, we need to add the FOR XML AUTO statement.

 

  1. SELECT * FROM Contact_Details FOR XML AUTO  

This query gives the output like,

  1. < Contact_Details Contact_ID=’001’ Contact_Number=’ 088888888’ Contact_Name=’Mohan’ Contact_Location=’Chennai’/>  
  2. < Contact_Details Contact_ID=’002’ Contact_Number=’ 099999999’ Contact_Name=’Abilash’ Contact_Location=’Bangalore’/>  

The XML which we got in output is not in user-friendly format. We need each field as an attribute so, that we can access the values using XPATH. To achieve that, we need to add the ELEMENTS parameter with the query.

 

  1. SELECT * FROM Contact_Details FOR XML AUTO, ELEMENTS  

This query gives the output like,

  1. < Contact_Details>  
  2.     <Contact_ID>001</Contact_ID>  
  3.     <Contact_Number>088888888</Contact_Number>  
  4.     <Contact_Name>Mohan</Contact_Name>  
  5.     <Contact_Location>Chennai</Contact_Location>  
  6. </ Contact_Details>  
  7. < Contact_Details>  
  8.     <Contact_ID>002</Contact_ID>  
  9.     <Contact_Number>099999999</Contact_Number>  
  10.     <Contact_Name>Abilash</Contact_Name>  
  11.     <Contact_Location>Bangalore</Contact_Location>  
  12. </ Contact_Details>  

So, this is the exact XML format we need.

Now, we are going to create XML DOCUMENT and write this output XML into that XML document in coding. To read the query in XML format, we need to execute the query using ExecuteXmlReader() function. 

  1. XmlReader XMLReader = new XmlReader();  
  2. XmlDocument XmlDoc = new XmlDocument();  
  3. SqlCommand Cmd = new SqlCommand(Query, Conn);  
  4. XMLReader = cmd.ExecuteXmlReader();  
  5. XPathDocument xPathDoc = new XPathDocument(XMLReader);  
  6. XPathNavigator xPathNavi = xPathDoc.CreateNavigator();  
  7. XmlDoc.LoadXml(XpathNavi.OuterXml);  

Now, we got the full structured XML Document. Using this, we will transform the data into HTML format using XSLT.

Before transforming, we need to create one XSLT file to assign the values from XMLDocument to HTML format.

Contact_Details.xslt

  1. <?xml version=”1.0” encoding=”utf-8”?>  
  2. <xsl:stylesheet version=”1.0” xmlns:xsl=”http://www.w3.org/1999/XSL/Tranform”>  
  3.     <xsl:output method=”xml” indent=”yes” omit-xml-declaration=”yes”>  
  4.         <xsl:template match=”/*”>  
  5.             <table>  
  6.                 <tr>// Column heading  
  7.                     <td>ContactID</td>  
  8.                     <td>ContactNumber</td>  
  9.                     <td>ContName</td>  
  10.                     <td>ContactLocation</td>  
  11.                 </tr>  
  12.                 <xsl:for-each select=”/ Contact_Details”>  
  13.                     <tr>// inserting XML data into HTML table  
  14.                         <td>  
  15.                             <xsl:value-of select=”/Contact_details/Contact_ID” </td> // using XPath we can access the value from XML Document  
  16.                                 <td>  
  17.                                     <xsl:value-of select=”/Contact_details/Contact_Number” </td>  
  18.                                 <td>  
  19.                               <xsl:value-of select=”/Contact_details/Contact_Name” </td>  
  20.                           <td>  
  21.                        <xsl:value-of select=”/Contact_details/Contact_Location” </td>  
  22.                     </tr>  
  23.                 </xsl:for-each>  
  24.             </table>  
  25.         </xsl:template>  
  26. </xsl:stylesheet>  

Now, we have XML Document and XSLT file. In the next step, we are going to transform the XML Document into HTML using XSLT. To do this, we pass the XMLDocument and XSLT file to separate functions and get fully formed HTML strings in return.

  1. Public static string TransformXMLTOHTML(XmlDocument XMLDoc, String XSLTFilename) {  
  2.     StringWriter HTMLString = new StringWriter();  
  3.     XslCompiledTransform Xmltransform = new XslCompiledTransform();  
  4.     XmlTransform.Load(XSLTFilename); // Load XSLT File  
  5.     Xmltranform.Transform(XMLDoc, null, Result); // transform XML into HTML  
  6.     Return HTMLString.ToString();  
  7. }  
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