C# DataGridView и Nullable типы

Question

Я пытался заставить DataGridView работать с типами Nullable, на данный момент речь идет о пустом перечислении.

Извините за массивные блоки кода, которые я пытаюсь опубликовать как Как можно больше информации, я думаю, я немного усложнил это ... Я почти уверен, что это свойство комбинированного списка работает для обнуляемых типов при использовании вне DataGridView.

ComboBox cb = new ComboBox();
if (this.IsNullable)
{
  cb.Items.Add("");
}
cb.Items.AddRange(this.PropertyType.GetEnumNames());
cb.DataBindings.Add(new Binding("Text", this, "Value", true, DataSourceUpdateMode.OnPropertyChanged, ""));
cb.Left = addLabel().Width + 2;
this.Width += cb.Left + cb.Width;
this.Controls.Add(cb);

Однако, когда я связываю Тип, который имеет свойство NULL .... Я не уверен, что делать дальше?

Создание DataGridView ...

// create a bindingsource here
BindingSource bindingSource = new BindingSource();
bindingSource.DataSource = this.PropertyType;
Binding b = new Binding("Tag", this, "Value", true, DataSourceUpdateMode.OnPropertyChanged, this.PropertyType);
b.BindingComplete += delegate (object sender, BindingCompleteEventArgs e)
{
  if (this.value != null)
  {
    bindingSource.DataSource = this.value;
  }
  else
  {
    this.Value = Activator
      .CreateInstance(typeof(List<>)
      .MakeGenericType(this.PropertyType));
    bindingSource.DataSource = this.value;
  };
};

// just update the supportingFileList Placeholder if it is it.
if (this.PropertyType == typeof(Feature.supporting_file) && this.featureEditFrom != null)
{
  DataGridView dgv = this.featureEditFrom.SupportingFilesList;
  dgv.DataSource = bindingSource;
  dgv.DataBindings.Add(b);
  UseComboBoxForEnumsAndBools(dgv);
}

Класс, который я пытаюсь создать, например DataGridView. Список

[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://mynamesapce.com")]
[System.Xml.Serialization.XmlRootAttribute(Namespace="http://mynamesapce.com", IsNullable=true)]
[System.Runtime.Serialization.DataContractAttribute(Name="supporting_file", Namespace="http://www.portbris.com.au/spatial.data")]
public partial class supporting_file : System.ComponentModel.INotifyPropertyChanged {

    [EditorBrowsable(EditorBrowsableState.Never)]
    private string fileNameField;

    [EditorBrowsable(EditorBrowsableState.Never)]
    private supporting_file_type fileTypeField;

    [EditorBrowsable(EditorBrowsableState.Never)]
    private System.Nullable<asset_status> fileStatusField;

    [EditorBrowsable(EditorBrowsableState.Never)]
    private System.Nullable<System.DateTime> fileDateField;

    [EditorBrowsable(EditorBrowsableState.Never)]
    private string fileCommentField;

    [System.Xml.Serialization.XmlElementAttribute(Order=0)]
    [System.Runtime.Serialization.DataMemberAttribute()]
    public string FileName {
        get {
            return this.fileNameField;
        }
        set {
            if ((this.fileNameField != null)) {
                if ((fileNameField.Equals(value) != true)) {
                    this.fileNameField = value;
                    this.OnPropertyChanged("FileName");
                }
            }
            else {
                this.fileNameField = value;
                this.OnPropertyChanged("FileName");
            }
        }
    }

    [System.Xml.Serialization.XmlElementAttribute(Order=1)]
    [System.Runtime.Serialization.DataMemberAttribute()]
    public supporting_file_type FileType {
        get {
            return this.fileTypeField;
        }
        set {
            if ((fileTypeField.Equals(value) != true)) {
                this.fileTypeField = value;
                this.OnPropertyChanged("FileType");
            }
        }
    }

    [System.Xml.Serialization.XmlElementAttribute(IsNullable=true, Order=2)]
    [System.Runtime.Serialization.DataMemberAttribute()]
    public System.Nullable<asset_status> FileStatus {
        get {
            return this.fileStatusField;
        }
        set {
            if ((this.fileStatusField != null)) {
                if ((fileStatusField.Equals(value) != true)) {
                    this.fileStatusField = value;
                    this.OnPropertyChanged("FileStatus");
                }
            }
            else {
                this.fileStatusField = value;
                this.OnPropertyChanged("FileStatus");
            }
        }
    }

    [System.Xml.Serialization.XmlElementAttribute(DataType="date", IsNullable=true, Order=3)]
    [System.Runtime.Serialization.DataMemberAttribute()]
    public System.Nullable<System.DateTime> FileDate {
        get {
            return this.fileDateField;
        }
        set {
            if ((this.fileDateField != null)) {
                if ((fileDateField.Equals(value) != true)) {
                    this.fileDateField = value;
                    this.OnPropertyChanged("FileDate");
                }
            }
            else {
                this.fileDateField = value;
                this.OnPropertyChanged("FileDate");
            }
        }
    }

    [System.Xml.Serialization.XmlElementAttribute(IsNullable=true, Order=4)]
    [System.Runtime.Serialization.DataMemberAttribute()]
    public string FileComment {
        get {
            return this.fileCommentField;
        }
        set {
            if ((this.fileCommentField != null)) {
                if ((fileCommentField.Equals(value) != true)) {
                    this.fileCommentField = value;
                    this.OnPropertyChanged("FileComment");
                }
            }
            else {
                this.fileCommentField = value;
                this.OnPropertyChanged("FileComment");
            }
        }
    }

    public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;

    /// <summary>
    /// Test whether FileStatus should be serialized
    /// </summary>
    public virtual bool ShouldSerializeFileStatus() {
        return FileStatus.HasValue;
    }

    /// <summary>
    /// Test whether FileDate should be serialized
    /// </summary>
    public virtual bool ShouldSerializeFileDate() {
        return FileDate.HasValue;
    }

    public virtual void OnPropertyChanged(string propertyName) {
        System.ComponentModel.PropertyChangedEventHandler handler = this.PropertyChanged;
        if ((handler != null)) {
            handler(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
        }
    }
}

[System.CodeDom.Compiler.GeneratedCodeAttribute("BentleyMap", "0.0.0.0")]
[System.SerializableAttribute()]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://mynamesapce.com")]
[System.Xml.Serialization.XmlRootAttribute(Namespace="http://mynamesapce.com", IsNullable=false)]
public enum supporting_file_type {

    /// <remarks/>
    Plan,

    /// <remarks/>
    Image,

    /// <remarks/>
    Document,

    /// <remarks/>
    Survey,

    /// <remarks/>
    Unspecified,
}