the process cannot access the file 'xxx.xml' because it is being used by another process - asp.net-mvc-4

Question

I googled a lot, but i dint get any solution for problem.
Iam trying to add a node in to a xxx.xml file, but its throwing an error
"the process cannot access the file 'xxx.xml' because it is being used by another process", below is my class
public class Registration
{
List Users;
List NewUsers;
string Userpath = string.Empty;
string NewUserpath = string.Empty;
string strUsername = string.Empty;
public bool FINDUSERNAME(string firstname, string lastname, string emailaddress, string country, string purchasedate, string username, string password)
{
//Put code to get the offers from database to Offers variable
if (ReadXML(firstname, lastname, emailaddress, country, purchasedate, username, password))
return true;
else
return false;
}
//bool ReadXML(XmlDocument xmlfile2)
bool ReadXML(string firstname, string lastname, string emailaddress, string country, string purchasedate, string username, string password)
{
try
{
XmlDocument receivedxml = new XmlDocument();
Userpath = HttpContext.Current.Server.MapPath("/SampleData/Registration.xml");
NewUserpath = HttpContext.Current.Server.MapPath("/SampleData/NewRegistration.xml");
XmlReaderSettings xrs = new XmlReaderSettings();
xrs.DtdProcessing = DtdProcessing.Ignore;
XmlReader xr = XmlReader.Create(Userpath, xrs);
if (xr != null)
{
//Setting the Root element
XmlRootAttribute xRoot = new XmlRootAttribute();
xRoot.ElementName = "Registration";
xRoot.IsNullable = true;
XmlSerializer deserializer = new XmlSerializer(typeof(Registration), xRoot);
Registration UserDetails = (Registration)deserializer.Deserialize(xr);
Users = UserDetails.Users;
foreach (var varuser in Users)
{
if (username == varuser.Username)
{
strUsername = varuser.Username;
return true;
}
}
if (strUsername == "")
{
//here iam trying to add a node to the xml
using (StreamWriter sw = new StreamWriter(File.Create(Userpath)))
{
sw.Write("<User><Firstname>"
+ firstname + "</Firstname><Lastname>"
+ lastname + "</Lastname><Country>"
+ country + "</Country><Purchasedate>"
+ purchasedate + "</Purchasedate><Emailaddress>"
+ emailaddress + "</Emailaddress><Username>"
+ username + "</Username><Password>"
+ password + "</Password></User>");
}
return false;
}
}
return false;
}
catch (Exception)
{
return false;
}
}
}
Thanks in Advance...

Answer 1

It looks like you are never closing your reader, you need to call xr.Close() at some point. Or as Johan suggested, wrap it in a using statement:
using (XmlReader xr = XmlReader.Create(Userpath, xrs))
{
//Setting the Root element
XmlRootAttribute xRoot = new XmlRootAttribute();
xRoot.ElementName = "Registration";
xRoot.IsNullable = true;
XmlSerializer deserializer = new XmlSerializer(typeof(Registration), xRoot);
Registration UserDetails = (Registration)deserializer.Deserialize(xr);
Users = UserDetails.Users;
foreach (var varuser in Users)
{
if (username == varuser.Username)
{
strUsername = varuser.Username;
return true;
}
}
if (strUsername == "")
{
//here iam trying to add a node to the xml
using (StreamWriter sw = new StreamWriter(File.Create(Userpath)))
{
sw.Write("<User><Firstname>"
+ firstname + "</Firstname><Lastname>"
+ lastname + "</Lastname><Country>"
+ country + "</Country><Purchasedate>"
+ purchasedate + "</Purchasedate><Emailaddress>"
+ emailaddress + "</Emailaddress><Username>"
+ username + "</Username><Password>"
+ password + "</Password></User>");
}
return false;
}
}
Also another note: I notice your method is named ReadXML, yet you are also writing XML in this method. This can be confusing, are you reading or writing? Part of your issue may also be that you are opening the file for reading, and then creating the file for writing?? I have not dealt with the C# Xml libs before but something doesn't seem right here. You might consider breaking this down more.