Simple C# code to add/delete XML elements?

Question

I have a XML file like this:

<?xml version='1.0' encoding='utf-8'?>
<sitegroup name = 'healthcare'>
        <site name='A' url='a.aspx'/>
        <site name='B' url='b.aspx'/>
</sitegroup>
<sitegroup name = 'diet'>
        <site name='C' url='c.aspx'/>
    <site name='D' url='d.aspx'/>
</sitegroup>

I am new to C#. I need a simple code to insert a new [site] (entered by user) under a particular [sitegroup] (also choosen by user). if the [sitegroup] supplied by user does not exist in the XML already, the code should create a new [sitegroup] at the end of the XML and then insert the new [site] in it.

Also, could you please let me know how to delete a particular [site] or/and a whole [sitegroup] from the XML?

Thanks a lot in advance.

Can you show what you have tried?

Siva Charan
– Siva Charan

2012-03-11 07:15:43 +00:00
Commented Mar 11, 2012 at 7:15 — Siva Charan
– Siva Charan, Commented Mar 11, 2012 at 7:15

Muhammad Hasan Khan · Accepted Answer · 2012-03-11 07:36:51Z

1

First of all your xml is invalid. Xml needs to have a root element. Let us asume your root element is sitegroups. Then you can use XLinq api in .NET Framework

class Program
{
    static void Main(string[] args)
    {
        string xml = @"<?xml version='1.0' encoding='utf-8'?>
<sitegroups>
<sitegroup name = 'healthcare'>
        <site name='A' url='a.aspx'/>
        <site name='B' url='b.aspx'/>
</sitegroup>
<sitegroup name = 'diet'>
        <site name='C' url='c.aspx'/>
    <site name='D' url='d.aspx'/>
</sitegroup>
</sitegroups>";

        var doc  = XDocument.Parse(xml);
        XElement siteGroup = doc.Element("sitegroups").Elements().First(e => e.Attribute("name").Value == "healthcare");
        var newSite = new XElement("site", new XAttribute("name", "C"),
                                           new XAttribute("url", "http://www.google.com"));
        siteGroup.Add(newSite);

        Console.WriteLine(doc.ToString());
    }
}

answered Mar 11, 2012 at 7:36

Muhammad Hasan Khan

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1 Comment

Manas Saha Over a year ago

Thanks a lot hasan. it helped a lot :)

Davin Tryon · Accepted Answer · 2012-03-11 07:38:59Z

this is the easiest way is linq to xml. You probably are going to have to wrap your xml structure in a root element <sitegroups>, otherwise any parsing API might not like it. I haven't run this code, but it should be very close:

    var sitegroupNameSelectedByUser = "execise";
    var siteName = "E";
    var siteUrl = "e.aspx";

    XDocument yourFile = XDocument.Load(@"yourFilename.xml");
    XElement existingSitegroup = xmldoc.XPathSelectElement("sitegroups/sitegroup[@name = sitegroupNameSelectedByUser]");

        if (existingSitegroup == null)
        {
            XElement sitegroup = new XElement("sitegroup",
                            new XAttribute("name", sitegroupNameSelectedByUser),
                            new XElement("site", 
                                new XAttribute("name", siteName),
                                new XAttribute("url", siteUrl));

            yourFile.Add(sitegroup);
        }

    yourFile.Save("new-filename.xml");

To delete you can select the element and then user the Remove();.

XDocument yourFile = XDocument.Load(@"yourFilename.xml");
XElement existingSitegroup = xmldoc.XPathSelectElement("sitegroups/sitegroup[@name = sitegroupNameSelectedByUser]");

if(existingSitegroup != null)
{
    existingSitegroup.Remove();
}

yourfile.Save("new-file.xml");

user1227804 · Accepted Answer · 2012-03-11 08:35:26Z

Here is a code that checks first if an element exists and subsequently adds sub-element:

    static XElement FindElementByNameAndAttr(XElement xml, XElement elem)
    {
        var q = (from x in xml.Elements()
                where x.Name == elem.Name
                      && elem.Attributes().All(a => 
                          x.Attributes().Any(b => 
                            (a.Name == b.Name) && (a.Value == b.Value)))
                select x)
                .FirstOrDefault();

        return q;
    }

    static void Main(string[] args)
    {
        string xml1 =
            @"<?xml version='1.0' encoding='utf-8'?>
            <root>
            <sitegroup name = 'healthcare'>
                    <site name='A' url='a.aspx'/>
                    <site name='B' url='b.aspx'/>
            </sitegroup>
            <sitegroup name = 'diet'>
                    <site name='C' url='c.aspx'/>
                <site name='D' url='d.aspx'/>
            </sitegroup>
            </root>
            ";

        string groupname = "jogging"; // "diet";
        string sitename = "K";
        string siteurl = "k.aspx";

        var root = XElement.Parse(xml1);

        XElement elem = new XElement("sitegroup", new XAttribute("name", groupname));
        XElement foundgroup;

        if((foundgroup = FindElementByNameAndAttr(root, elem)) == null)
        {
            root.Add(elem);
            foundgroup = elem;
        }

        var newsite = new XElement("site", new XAttribute("name", sitename));

        XElement foundsite;
        if ((foundsite = FindElementByNameAndAttr(foundgroup, newsite)) != null)
        {
            var attr = foundsite.Attribute("url");
            if (attr != null && attr.Value != siteurl)
            {
                // error handling here
                throw new Exception("TODO");
            }
        }
        else
        {
            foundgroup.Add(newsite);
            foundsite = newsite;
        }


        foundsite.SetAttributeValue("url", siteurl);

        Console.WriteLine(root.ToString());
    }

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