C# how to foreach loop an XML document and modify a value

Question

I have an XML document that I want to modify the connectionstrings to. How do I do a foreach loop and in this example modify the value of LocalSqlServer?

<connectionStrings>
    <clear />
    <add name="Localip" connectionString="Data Source=db01;Initial Catalog=TestA;Integrated Security=True;"
     providerName="System.Data.SqlClient" />
    <add name="LocalSqlServer" connectionString="Data Source=db02;Failover Partner=db01;Initial Catalog=TestB;Integrated Security=True;"
     providerName="System.Data.SqlClient" />
    <add name="ServerAp" connectionString="Data Source=LAPTOP;Initial Catalog=testc;Integrated Security=True;" providerName="System.Data.SqlClient"/>
</connectionStrings>

This is what I've tried, but I really just want to modify the value not the whole content. For this example I want to change:

<add name="LocalSqlServer" connectionString="Data Source=db02;Failover Partner=db01;Initial Catalog=TestB;Integrated Security=True;"
     providerName="System.Data.SqlClient" />

<add name="LocalSqlServer" connectionString="Data Source=db07;Failover Partner=db07;Initial Catalog=TestB;Integrated Security=True;"
     providerName="System.Data.SqlClient" />

This is what I've tried:

System.Xml.XmlDocument xmlDocument = new System.Xml.XmlDocument();
        xmlDocument.Load(@"C:\xml.xml");
        XmlNodeList elemList = xmlDocument.GetElementsByTagName("connectionStrings");
        for (int i = 0; i < elemList.Count; i++)
        {
            foreach (XmlNode chldNode in elemList[i].ChildNodes)
            {
                Console.WriteLine(chldNode.Name.ToString());
                if (chldNode.Name.ToString() == "add")
                {
                    foreach (XmlAttribute xmlAtt in chldNode.Attributes)
                    {
                        if (xmlAtt.Value == "LocalSqlServer")
                        {
                            xmlAtt.InnerXml = "MyNewValue";
                            xmlDocument.Save(@"C:\xml2.xml");
                            break;
                        }
                    }
                }
            }
        }

connectionStrings is an attribute not an element. add is the element. — L.B
– L.B, Commented Nov 6, 2012 at 15:37
@L.B this modifies the line i'm looking for, but all i want to modify is the value not the entire string, I know xmlAtt.InnerXMl modifies the whole thing but thats not what I want to do — user222427
– user222427, Commented Nov 6, 2012 at 15:38
In this case, I think that an XPath query would be far more simple to implement and far more simple to read. — Steve B
– Steve B, Commented Nov 6, 2012 at 15:40

L.B · Accepted Answer · 2012-11-06 15:47:37Z

1

var xDoc = XDocument.Load(@"C:\xml.xml")
var node = xDoc.XPathSelectElement("//add[@name='LocalSqlServer']");
node.Attribute("connectionString").Value = "some value";

or as SteveB suggested

var node = xDoc.XPathSelectElement("//connectionStrings/add[@name='LocalSqlServer']");

edited Nov 6, 2012 at 15:47

answered Nov 6, 2012 at 15:40

L.B

116k20 gold badges189 silver badges229 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Steve B Over a year ago

+1 Using XPath is a lot simpler than looping the nodes. I would use however, the following query: configuration/connectionString/add[@name='LocalSqlServer'] to avoid selecting other unwanted add node in the xml document (add is too generic and limiting by the name is not enough)

Knaģis · Accepted Answer · 2012-11-06 15:38:25Z

0

Using System.Xml.Linq:

var xml = XDocument.Load(fileName);
var localSqlServer = xml.Descendants("connectionStrings").Elements("add").FirstOrDefault(o => o.Attribute("name").Value == "LocalSqlServer");
if (localSqlServer != null)
    localSqlServer.SetAttributeValue("connectionString", "Your New Connection String");
xml.Save(fileName);

answered Nov 6, 2012 at 15:38

Knaģis

21.6k9 gold badges71 silver badges80 bronze badges

3 Comments

Knaģis Over a year ago

it is defined on XDocument class, it is not an extension method

user222427 Over a year ago

I'm getting Error 3 'System.Xml.XmlDocument' does not contain a definition for 'Descendants' and no extension method 'Descendants' accepting a first argument of type 'System.Xml.XmlDocument' could be found (are you missing a using directive or an assembly reference?)

Knaģis Over a year ago

It is XDocument (defined in System.Xml.Linq), not System.Xml.XmlDocument (defined in System.Xml). XDocument is the new Microsoft recommended way of working with XML in .NET since .NET 3.5

Collectives™ on Stack Overflow

C# how to foreach loop an XML document and modify a value

2 Answers 2

1 Comment

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related