C# XML: System.InvalidOperationException

Question

I have been learning C#'s XML with a project however I keep getting the InvalidOperationException. I have put the code below

        XmlTextWriter writer = new XmlTextWriter(path, System.Text.Encoding.UTF8);
        writer.WriteStartDocument(true);
        writer.Formatting = Formatting.Indented;
        writer.Indentation = 4;

        writer.WriteStartElement("User Info");
            writer.WriteStartElement("Name");
                writer.WriteString(userName);
            writer.WriteEndElement();
            writer.WriteStartElement("Tutor Name");
                writer.WriteString(tutorName);
            writer.WriteEndElement();
        writer.WriteEndElement();

        writer.WriteStartElement("Course Data"); /*This is where the exception points to*/
            foreach (UserCourse c in courses)
            {
                String cn = c.Name;
                writer.WriteStartElement(cn);

                foreach (UserUnit u in c.Units)
                {
                    writer.WriteStartElement(u.Name.ToString());

                    foreach (UserObjective o in u.Objectives)
                    {
                        writer.WriteStartElement(o.Name.ToString());
                        writer.WriteString(o.Score.ToString());
                        writer.WriteEndElement();
                    }
                    writer.WriteEndElement();
                }
                writer.WriteEndElement();
            }
        writer.WriteEndElement();

        writer.WriteEndDocument();
        writer.Close();

Perhaps someone can see what I am doing wrong. I appreciate any help!

Creating a user record that uses XML to save an external file. Where the course and its subsections are saved as well. — Jeremy Beare
– Jeremy Beare, Commented Jun 22, 2015 at 6:24
When I was learning C#'s XML first time, I spent so much time learning how XmlWriter and XmlReader works. It is great to understand this first, understand how it's actually working. However, I strongly advise you not to waste your time working with it. Use XML Serialization and classes. It lets you avoid over-coding. The whole code provided by you in a question could be replaced with a class definition and 3 rows of code. Read more here: msdn.microsoft.com/en-us/library/58a18dwa(v=vs.110).aspx — Yeldar Kurmangaliyev
– Yeldar Kurmangaliyev, Commented Jun 22, 2015 at 6:30

Hassan Nisar · Accepted Answer · 2015-06-22 06:37:36Z

3

XML Element names cannot contain spaces.

Refer to XML Naming Rules.

Also it seems like you should have one root element. Like CourseData should be inside UserInfo.

Checkout Fiddle

edited Jun 22, 2015 at 6:37

answered Jun 22, 2015 at 6:07

Hassan Nisar

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6 Comments

Jeremy Beare Over a year ago

Wow. I had no idea! It does not seem to have worked though

Jeremy Beare Over a year ago

Really? Could you post what code you had so I can do a comparison?

Hassan Nisar Over a year ago

@JeremyBeare click on Fiddle link to get more idea. Hope it will help.

Jeremy Beare Over a year ago

I used the Fiddle link to check and compare. I have made all the changes and it still causes the Exception. If I remove the "CourseData" elemental and all within it, the code works fine.

Hassan Nisar Over a year ago

Create a new Fiddle and share the link.

|

User12345 · Accepted Answer · 2015-06-22 06:27:22Z

Is "User Info" and "Course Data" is a different entity. If it is so, I think you may encapsulate them in one entity.

            XmlTextWriter writer = new XmlTextWriter(path, System.Text.Encoding.UTF8);
            writer.WriteStartDocument(true);
            writer.Formatting = Formatting.Indented;
            writer.Indentation = 4;

            writer.WriteStartElement("My Entity"); /* It is a biggest one*/
            writer.WriteStartElement("User Info");
            writer.WriteStartElement("Name");
            writer.WriteString(userName);
            writer.WriteEndElement();
            writer.WriteStartElement("Tutor Name");
            writer.WriteString(tutorName);
            writer.WriteEndElement();
            writer.WriteEndElement();

            writer.WriteStartElement("Course Data"); /*This is where the exception points to*/
            foreach (UserCourse c in courses)
            {
                String cn = c.Name;
                writer.WriteStartElement(cn);

                foreach (UserUnit u in c.Units)
                {
                    writer.WriteStartElement(u.Name.ToString());

                    foreach (UserObjective o in u.Objectives)
                    {
                        writer.WriteStartElement(o.Name.ToString());
                        writer.WriteString(o.Score.ToString());
                        writer.WriteEndElement();
                    }
                    writer.WriteEndElement();
                }
                writer.WriteEndElement();
            }
            writer.WriteEndElement();
            writer.WriteEndElement();

            writer.WriteEndDocument();
            writer.Close();

They are both in the User Info entity. It is a very short entity.

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