Question

我找到了一个很好的代码验证代码示例：

public class StringViewModel : ViewModelBase, IComparable
{
    private string _value;
    private string _originalValue;

    public StringViewModel(string value)
    {
        _value = value;
        _originalValue = value;
    }

    // Der eigentliche Wert.
    public string Value
    {
        get { return _value; }
        set
        {
            if (value != _value)
            {
                _value = value;
                RaisePropertyChanged("Value");
                HasChanges = _value != _originalValue && !(string.IsNullOrEmpty(_value) && string.IsNullOrEmpty(_originalValue));
            }
        }
    }

    public override void AcceptChanges()
    {
        _originalValue = _value;
        HasChanges = false;
        HasError = false;
    }

    public override void UndoChanges()
    {
        Value = _originalValue;
        HasError = false;
    }

    // Muss implementiert werden, damit die Sortierung im CollectionView funktioniert.
    public int CompareTo(object obj)
    {
        if (obj == null) return 1;
        if (object.ReferenceEquals(this, obj)) return 0;
        StringViewModel other = obj as StringViewModel;
        return string.Compare(this._value, other._value);
    }

    public override string ToString()
    {
        return _value;
    }
}

现在我想让它更通用，所以我需要在运行时创建下面的2个值：

private T? _value;
private T? _originalValue;

因为我想做类似的事情：

public class ItemModel : IComparable, INotifyEXTEND
{
    private ??? _value;
    private ??? _originalValue;

    public ItemModel(string value)
    {
            _value = value;
            _originalValue = value;
    }

    public ??? Value
    {
        get { return _value; }
        set
        {
            if (value != _value)
            {
                _value = value;
                RaisePropertyChanged("Value");
                HasChanges = _value != _originalValue && !(string.IsNullOrEmpty(_value) && string.IsNullOrEmpty(_originalValue));
            }
        }
    }

    public override void AcceptChanges()
    {
        _originalValue = _value;
        HasChanges = false;
        HasError = false;
    }

    public override void UndoChanges()
    {
        Value = _originalValue;
        HasError = false;
    }

    public int CompareTo(object obj)
    {
        if (obj == null) return 1;
        if (object.ReferenceEquals(this, obj)) return 0;
        ??? other = obj as ???;
        return string.Compare(this._value, other._value);
    }

    public override string ToString()
    {
        return _value;
    }
}

所以我可以这样使用它：

public class PersonViewModel : ViewModelBase
{

    private Person _person;
    private ItemModel _lastname;
    private ItemModel _birthdate;
    private bool _isNew;

    // Otherstuff
}

有关如何执行此操作的任何建议？（一些示例代码片段或链接会很好）

Answer 1

您需要使用泛型：

public class ItemModel<T> : IComparable<ItemModel<T>>, INotifyEXTEND where T : IComparable<T>

Answer 2

我的解决方案在SLaks启发暗示之后（感谢你）我跳了它帮助某人

public class ValueModel<T> : IComparable
{
    private object _value;
    private object _originalValue;

    public T Value
    {
        get { return (T)_value; }
        set
        {
            if ((object)value != _value)
            {
                _value = value;
            }
        }
    }

    public ValueModel(T value)
    {
        _value = value;
        _originalValue = value;
    }

    public void AcceptChanges()
    {
        _originalValue = _value;
    }

    public void UndoChanges()
    {
        Value = (T)_originalValue;
    }

    // Muss implementiert werden, damit die Sortierung im CollectionView funktioniert.
    public int CompareTo(object obj)
    {
        if (obj == null) return 1;
        if (object.ReferenceEquals(this, obj)) return 0;
        ValueModel<T> other = obj as ValueModel<T>;
        if (typeof(T) == typeof(String))
            return string.Compare(this._value.ToString(), other._value.ToString());
        else
            return ((IComparable)_value).CompareTo(other._value);
    }
}

您可以像使用

一样使用它

public ValueModel<int> Id {get;set;}

执行类似

的方法

Id.AcceptChanges();

并绑定它

TextBox Text="{Binding Id.Value}"

在运行时创建未知类型的值

2 个答案: