Question

Hi I am wondering how I can keep the previous records with my stream writer, if I use the below code it works fine when the student record is created but when I create a second student record the previous record is gone? How can I keep all records?

    public void AddStudent(Student student)
    {
        students.Add(student);
        XmlSerializer s = new XmlSerializer(typeof(Student));
        TextWriter w = new StreamWriter("c:\\list.xml");
        s.Serialize(w, student);
        w.Close();
    }

EDIT UPDATE:

From the partial answer below I keep getting this error Type WcfServiceLibrary1.Student' in Assembly 'WcfServiceLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null is not marked as serializable

I have decorated the Student Class with [Serializable()] so im not sure whats going on?

Answer 1

Use this overload of StreamWriter’s constructor to append new data instead of overwriting.

TextWriter w = new StreamWriter("c:\\list.xml", true);

Update:
I see, it works only with BinaryFormatter and not with XmlSerializer, because second write makes XML invalid. Unless you need XML format for some reason, using binary format is easier. This should work:

   static void WriteStudent(Student S)
    {
        BinaryFormatter f = new BinaryFormatter();
        using (Stream w = new FileStream("c:\\list.dat", FileMode.Append))
        {
            f.Serialize(w, S);
        }
    }

    static List<Student> ReadStudents()
    {
        BinaryFormatter f = new BinaryFormatter();

        using (Stream w = new FileStream("c:\\list.dat", FileMode.Open))
        {
            List<Student> students = new List<Student>();
            while (w.Position < w.Length)
            {
                students.Add((Student)f.Deserialize(w));
            }
            return students;
        }
    }