NullReferenceException while saving XML File with Linq

Question

I keep getting a NullReferenceException at this line UserRoot.Element("User_ID").Value = User.User_ID.ToString();

What exactly am I doing wrong?

Here's the majority of the code for that method

            if (File.Exists(Path2UserDB + User.User_ID.ToString() + ".db") == false)
            {
                File.Create(Path2UserDB + User.User_ID.ToString() + ".db");

            }
            XElement UserRoot = new XElement("User");
            UserRoot.Element("User_ID").Value = User.User_ID.ToString();
            UserRoot.Element("Full_Name").Value = User.Full_Name;
            UserRoot.Element("Gender").Value = User.Gender;
            UserRoot.Element("BirthDate").Value = User.BirthDate.ToString();
            UserRoot.Element("PersonType").Value = User.PersonType.ToString();
            UserRoot.Element("Username").Value = User.Username;
            UserRoot.Element("Password").Value = User.Password;
            UserRoot.Element("Email_adddress").Value = User.Email_Address;
            XDocument UserDoc = new XDocument();
            UserDoc.Save(Path2UserDB + User.User_ID.ToString() + ".db");

Thanks

I know that saving Usernames and Passwords in plain text is incredibly unsafe, but this is only going to be accessed by one process that I will eventually implement strong security

SLaks · Accepted Answer · 2010-12-12 20:14:33Z

2

The Element("User_ID") method returns an existing element named <User_ID>, if any.

Since your XML element is empty, it returns null.

You should create your XML like this:

var userDoc = new XDocument(
    new XElement("User",
        new XElement("User_ID", User.User_ID),
        new XElement("Full_Name", User.Full_Name),
        new XElement("Gender", User.Gender),
        ...
    )
);

Alternatively, you can call the Add method to add a node to an existing element.

edited Dec 12, 2010 at 20:14

answered Dec 12, 2010 at 20:06

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

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

Comments

Waleed Al-Balooshi · Accepted Answer · 2010-12-12 20:12:34Z

2

You are getting this error, because there is no XML element called User_ID under UserRoot to set its value. If you comment it out, you will get the same error on the next line and so on for every other Element, since you haven't added Elements with thos names. To create the tree that you want, try this:

XElement UserRoot =
    new XElement("User",
        new XElement("User_ID", User.User_ID.ToString()),
        new XElement("Full_Name", User.Full_Name), 
        new XElement("Gender", User.Gender),
        new XElement("BirthDate", User.BirthDate.ToString()),
        new XElement("PersonType", User.PersonType.ToString()),
        new XElement("Username", User.Username),
        new XElement("Password", User.Password),
        new XElement("Email_adddress", User.Email_Address)
    );

The following MSDN link on XML Tree Creation with XElement will be of help.

answered Dec 12, 2010 at 20:12

Waleed Al-Balooshi

6,40625 silver badges22 bronze badges

2 Comments

Jarred Sumner Over a year ago

Both you and the above guy are right, I would checkbox both if I could

Waleed Al-Balooshi Over a year ago

@Indebi no problem; by the time I posted my solution, I noticed that Slaks had already updated his answer to include the proper code, so he should get the checkmark. I am happy that it all worked out for you though :)

Jack Marchetti · Accepted Answer · 2010-12-12 20:06:29Z

0

You want to check if the value is null or empty before running methods on it.

if(!String.IsnullorEmpty(User.User_ID))
       UserRoot.Element("User_ID").Value = User.User_ID.ToString();

answered Dec 12, 2010 at 20:06

Jack Marchetti

15.8k14 gold badges85 silver badges119 bronze badges

2 Comments

digEmAll Over a year ago

I think the problem is that UserRoot.Element("User_ID") is null, not User.User_ID

Jack Marchetti Over a year ago

Gotcha, well he should check that too

Collectives™ on Stack Overflow

NullReferenceException while saving XML File with Linq

3 Answers 3

Comments

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related