bind dropdown with XML file

Question

I have this XML file:

<questions>
  <question id="title">
    <option>
      <text>Mr</text>
      <value>Mr</value>
    </option>
    <option>
      <text>Ms</text>
      <value>Ms</value>
    </option>
  </question>
  <question id="organisation">
    <option>
      <text>org1</text>
      <value>org1</value>
    </option>
    <option>
      <text>org2</text>
      <value>org2</value>
    </option>
  </question>
</questions>

How do I bind each question to a specific drop-down in c#?

Thanks

Darin Dimitrov · Accepted Answer · 2010-11-30 18:12:19Z

2

You could use a XmlDataSource. Because your XML is not conform to what this control expects you will need to adapt it by using a XSL transformation.

So Step 1:

Define a XSL transformation (~/App_Data/questions.xslt):

<?xml version="1.0" encoding="utf-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="questions">
    <questions>
      <xsl:apply-templates select="question"/>
    </questions>
  </xsl:template>
  <xsl:template match="option">
    <option>
      <xsl:attribute name="text">
        <xsl:value-of select="text"/>
      </xsl:attribute>
      <xsl:attribute name="value">
        <xsl:value-of select="value"/>
      </xsl:attribute>
    </option>
  </xsl:template>
</xsl:stylesheet>

Step 2:

Use it:

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head id="Head1" runat="server">
    <title></title>
</head>
<body>
    <form id="Form1" runat="server">
        <asp:DropDownList 
            ID="ddl" 
            runat="server" 
            DataSourceID="ds" 
            DataTextField="text" 
            DataValueField="value" 
        />

        <asp:XmlDataSource 
            ID="ds" 
            runat="server" 
            DataFile="~/App_Data/questions.xml" 
            TransformFile="~/App_Data/questions.xslt" 
            XPath="//option" 
        />
    </form>
</body>
</html>

Notice how the TransformFile property on the data source is pointing to the XSL file.

answered Nov 30, 2010 at 18:12

Darin Dimitrov

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4 Comments

user Over a year ago

the format of the XML is not fixed. Is there a different format that woudn't need the XSL transformation?

Darin Dimitrov Over a year ago

Yes, it's the one produced by the XSL transformation. If it is not fixed you will need to fix it or you can't use it. Another possibility would be to generate this XSL file dynamically based on the syntax of your XML file but I would really recommend you normalizing it.

user Over a year ago

ok so what would be the XPath to match only the values under: question id="title"

mikesigs Over a year ago

Xpath would be: /Question[id="title"]/Option. One thing to note for the XmlDataSource is that caching is enabled by default which could cause you some headaches. I usually turn it off i.e. EnableCache="False".

andrei m · Accepted Answer · 2010-11-30 18:09:19Z

0

You could use the XmlDataSource class to bind the XML data to your control.

answered Nov 30, 2010 at 18:09

andrei m

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Comments

Bazzz · Accepted Answer · 2010-12-01 18:35:08Z

0

You can use XDocument

string xml = ""; /* your xml */
XDocument xDocument = XDocument.Parse(xml);
foreach(XElement questionElement in xDocument.Root.Elements("question"))
{
 foreach(XElement optionElement in questionElement.Elements("option"))
 {
  string text = optionElement.Element("text").Value;
  string value = optionElement.Element("value").Value;
  /* do something with them here */
 }
}

Using the attribute id to bind all select boxes:

string xml = ""; /* your xml */
XDocument xDocument = XDocument.Parse(xml);
foreach(XElement questionElement in xDocument.Root.Elements("question"))
{
 string id = questionElement.Attribute("id").Value;
 foreach(XElement optionElement in questionElement.Elements("option"))
 {
   string text = optionElement.Element("text").Value;
   string value = optionElement.Element("value").Value;
   /* bind selectbox options here, using id,text,value */
 }
}

Using id to bind one select box:

string id = "title";  
string xml = ""; /* your xml */
XDocument xDocument = XDocument.Parse(xml);  
XElement questionElement = xDocument.Root.Elements("question").SingleOrDefault(e => e.Attribute("id").Value == "title");
if (questionElement != null)
{
 foreach(XElement optionElement in questionElement.Elements("option"))
 {
  string text = optionElement.Element("text").Value;
  string value = optionElement.Element("value").Value;
  /* bind selectbox options here, using id,text,value */
 }
}

edited Dec 1, 2010 at 18:35

answered Nov 30, 2010 at 19:36

Bazzz

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3 Comments

user Over a year ago

thanks. how would you match only the nodes of a specific question, ie. question id="title"?

Bazzz Over a year ago

xDocument.Elements("question").Where(e => e.Attribute("id").Value == "title"); will do that. You'll probably have to add some Exception catching for the situation when the id attribute does not exist though. Also consider the new piece of code that I posted.

mikesigs Over a year ago

I like this approach but rather than looping and adding items to the List (which you'd have to do on each postback) you could DataBind the list to a collection of anonymous types.

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