Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

Why is XmlSerializer throwing an InvalidOperationException?

    public void Save() {
          XmlSerializer Serializer = new XmlSerializer(typeof(DatabaseInformation));
          /*
          A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll
          A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll
          A first chance exception of type 'System.InvalidOperationException' occurred in System.Xml.dll
          */

          // ....
     }

This is the whole class if you need it:

public class DatabaseInformation
{
    /* Create new database */
    public DatabaseInformation(string name) {
        mName = name;
        NeedsSaving = true;
        mFieldsInfo = new List<DatabaseField>();
    }

    /* Read from file */
    public static DatabaseInformation DeserializeFromFile(string xml_file_path)
    {
    XmlSerializer Serializer = new XmlSerializer(typeof(DatabaseInformation));
        TextReader r = new StreamReader(xml_file_path);
        DatabaseInformation ret = (DatabaseInformation)Serializer.Deserialize(r);
        r.Close();
        ret.NeedsSaving = false;
        return ret;
    }

    /* Save */
    public void Save() {
    XmlSerializer Serializer = new XmlSerializer(typeof(DatabaseInformation));
        if (!mNeedsSaving)
            return;

        TextWriter w = new StreamWriter(Path.Combine(Program.MainView.CommonDirectory.Get(), Name + ".xml"), false);
        Serializer.Serialize(w, this);
        w.Close();
        NeedsSaving = false;
    }

    private string mName;
    public string Name { get { return mName; } }

    private bool mNeedsSaving;
    public bool NeedsSaving { get { return mNeedsSaving; } set { mNeedsSaving = value; Program.MainView.UpdateTitle(value); } }

    private bool mHasId;
    public bool HasId { get { return mHasId; } }

    List<DatabaseField> mFieldsInfo;
}

(PS: if you have any tips to improve my code feel free to share, I'm a C# beginner)

like image 392
qster Avatar asked Mar 23 '10 07:03

qster


People also ask

Why do we use XmlSerializer class?

Serialization/ De-serialization allow communication with another application by sending and receiving data. With XmlSerializer, you can control how objects are encoded into XML. Call the Serialize method with the parameters of the StreamWriter and object to serialize.

Can I make XmlSerializer ignore the namespace on Deserialization?

Yes, you can tell the XmlSerializer to ignore namespaces during de-serialization. Note this is the kind of thing I meant. You are not telling the XmlSerializer to ignore namespaces - you are giving it XML that has no namespaces.

How does the XmlSerializer work C#?

The XmlSerializer creates C# (. cs) files and compiles them into . dll files in the directory named by the TEMP environment variable; serialization occurs with those DLLs. These serialization assemblies can be generated in advance and signed by using the SGen.exe tool.

Is XmlSerializer thread safe?

Since XmlSerializer is one of the few thread safe classes in the framework you really only need a single instance of each serializer even in a multithreaded application.


2 Answers

To serialize/deserialize your type it needs to have parameterless constructor. Check out here :

A class must have a default constructor to be serialized by XmlSerializer.

like image 117
Andrew Bezzub Avatar answered Oct 04 '22 22:10

Andrew Bezzub


I was also getting this exception, but it wasn't due to missing a default constructor. I had some extra properties (a List and Dictionary) which aren't part of the XML document.

Decorating those properties with [XmlIgnore] solved the problem for me.

like image 40
Dave Andersen Avatar answered Oct 04 '22 22:10

Dave Andersen