Question

i am trying to change the count attribute within instances, the xml is below

<ServiceConfiguration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" serviceName="" osFamily="1" osVersion="*"      
xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration">
<Role name="WebRole1">
    <ConfigurationSettings>
       <Setting name="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" />
    </ConfigurationSettings>
    <Instances count="1" />
    <Certificates />
</Role>
</ServiceConfiguration>

I have tried the following that i saw in another question, but i get the error “Object reference not set to an instance of an object.”

changeConfigXDoc.Root.Element("ServiceConfiguration").Element("Role").Element("Instances").Attribute("count").Value=ChangeInstanceText.Text;

Answer 1

You should take the namespace into consideration

XNamespace ns = XNamespace.Get("http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration");
changeConfigXDoc
    .Element(ns + "ServiceConfiguration")
    .Element(ns + "Role")
    .Element(ns + "Instances")
    .Attribute("count").Value = ChangeInstanceText.Text;

Or

XNamespace ns = XNamespace.Get("http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration");
changeConfigXDoc
    .Descendants(ns+"Instances")
    .First()
    .Attribute("count").Value = "666";