将通用属性写入 MVVM 中的类文件

Question

我有属性CaretIndex 和InputValue 我的ViewModel 用于Highlighting ComboBox Items which matches the text in PART_EditableTextBox of ComboBox。 所以，我希望它们在一个单独的文件中。因此，我不必在每次声明新视图时都输入它们。但这里的问题是这些CaretIndex 和InputValue 属性的setter 部分依赖于另一个类的另一个名为IsHighlighted 的属性，并且该类可能会因每个新的数据集合而改变。

我有一个 ViewModel 如下：

public class GroupsViewModel : INotifyPropertyChanged
{
    public GroupsViewModel()
    {
        using (DBEntities db = new DBEntities())
        {
            GroupsAndCorrespondingEffects = (from g in db.Groups
                                             select new GroupAndCorrespondingEffect
                                                        {
                                                            GroupName = g.Name,
                                                            CorrespondingEffect = g.Type_Effect.Name
                                                        }
                                            ).ToList();

            GroupsAndCorrespondingEffects.Add
                                            (
                                                new GroupAndCorrespondingEffect
                                                        {
                                                            GroupName = " Primary",
                                                            CorrespondingEffect = ""
                                                        }
                                            );

            GroupsAndCorrespondingEffects = GroupsAndCorrespondingEffects.OrderBy(g => g.GroupName).ToList();

            Items = (from e in db.Type_Effect
                     select e.Name).ToList();
        }
    }

    public static GroupsViewModel CurrentInstance { get { return Instance; } }

    private List<GroupAndCorrespondingEffect> _groupsAndCorrespondingEffects;
    public List<GroupAndCorrespondingEffect> GroupsAndCorrespondingEffects
    {
        get
        {
            return _groupsAndCorrespondingEffects;
        }
        set
        {
            _groupsAndCorrespondingEffects = value;
            OnPropertyChanged("GroupsAndCorrespondingEffects");
        }
    }

    private int _caretIndex;
    public int CaretIndex
    {
        get { return _caretIndex; }
        set
        {
            _caretIndex = value;
            OnPropertyChanged("CaretIndex");

            for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++)
            {

                string WordToSearch = InputValue;

                if (_caretIndex != 0 && _caretIndex > 0)
                {
                    WordToSearch = InputValue.Substring(0, _caretIndex);
                }

                if (WordToSearch != null)
                {
                    GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(WordToSearch);
                }
            }
        }
    }

    private string _inputValue;
    public string InputValue
    {
        get { return _inputValue; }
        set
        {
            _inputValue = value;
            OnPropertyChanged("GroupsAndCorrespondingEffects");

            for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++)
            {

                string WordToSearch = _inputValue;

                if (_caretIndex != 0 && _caretIndex > 0 && _caretIndex < _inputValue.Length)
                {
                    WordToSearch = _inputValue.Substring(0, _caretIndex);
                }

                GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(WordToSearch);

            }
        }
    }

    public void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

用于获取不同格式数据的Helper Class（Get data in two Columns for a comboBox.）如下：（该类的IsHighLighted属性在CaretIndex和@的setter部分引用987654331@.)

public class GroupAndCorrespondingEffect : INotifyPropertyChanged
{
    private string _groupName;
    public string GroupName
    {
        get
        {
            return _groupName;
        }
        set
        {
            _groupName = value;
            OnPropertyChanged("GroupName");
        }
    }

    private string _correspondingEffect;
    public string CorrespondingEffect
    {
        get
        {
            return _correspondingEffect;
        }
        set
        {
            _correspondingEffect = value;
            OnPropertyChanged("CorrespondingEffect");
        }
    }

    private bool _isHighlighted;
    public bool IsHighlighted
    {
        get
        {
            return _isHighlighted;
        }
        set
        {
            _isHighlighted = value;
            OnPropertyChanged("IsHighlighted");
        }
    }

    public void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

Answer 1

如果我正确理解您的问题，您想要做的是将 CaretIndex 和 InputValue 等常见位移动到 抽象基 类。

请参阅下面的示例代码以了解我的意思：

基类

public abstract class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private int _caretIndex;

    public int CaretIndex
    {
        get { return _caretIndex; }
        set
        {
            _caretIndex = value;
            OnPropertyChanged("CaretIndex");
            OnCaretIndexChanged();
        }
    }

    private string _inputValue;
    public string InputValue
    {
        get { return _inputValue; }
        set
        {
            _inputValue = value;
            OnPropertyChanged("InputValue");
            OnInputValueChanged();
        }
    }

    protected abstract void OnCaretIndexChanged();

    protected abstract void OnInputValueChanged();
}

如果您检查 CaretIndex 和 InputValue 的 Setter，它们将分别执行 OnCaretIndexChanged 和 OnInputValueChanged 抽象方法 - 您将在派生类中实现这些方法。

现在，您的 GroupViewModel 将从 ViewModelBase 继承并实现这两个抽象方法。

public class GroupsViewModel : ViewModelBase
{
    public GroupsViewModel()
    {
        using (DBEntities db = new DBEntities())
        {
            GroupsAndCorrespondingEffects = (from g in db.Groups
                                             select new GroupAndCorrespondingEffect
                                             {
                                                 GroupName = g.Name,
                                                 CorrespondingEffect = g.Type_Effect.Name
                                             }
                                            ).ToList();

            GroupsAndCorrespondingEffects.Add
                                            (
                                                new GroupAndCorrespondingEffect
                                                {
                                                    GroupName = " Primary",
                                                    CorrespondingEffect = ""
                                                }
                                            );

            GroupsAndCorrespondingEffects = GroupsAndCorrespondingEffects.OrderBy(g => g.GroupName).ToList();

            Items = (from e in db.Type_Effect
                     select e.Name).ToList();
        }
    }

    public static GroupsViewModel CurrentInstance { get { return Instance; } }

    private List<GroupAndCorrespondingEffect> _groupsAndCorrespondingEffects;
    public List<GroupAndCorrespondingEffect> GroupsAndCorrespondingEffects
    {
        get
        {
            return _groupsAndCorrespondingEffects;
        }
        set
        {
            _groupsAndCorrespondingEffects = value;
            OnPropertyChanged("GroupsAndCorrespondingEffects");
        }
    }

    protected override void OnCaretIndexChanged()
    {
        for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++)
        {
            string wordToSearch = InputValue;

            if (CaretIndex != 0 && CaretIndex > 0)
            {
                wordToSearch = InputValue.Substring(0, CaretIndex);
            }

            if (wordToSearch != null)
            {
                GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(wordToSearch);
            }
        }
    }

    protected override void OnInputValueChanged()
    {
        OnPropertyChanged("GroupsAndCorrespondingEffects");

        for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++)
        {

            string wordToSearch = InputValue;

            if (CaretIndex != 0 && CaretIndex > 0 && CaretIndex < InputValue.Length)
            {
                wordToSearch = InputValue.Substring(0, CaretIndex);
            }

            GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(wordToSearch);

        }
    }
}

如果您想抽象从 GroupAndCorrespondingEffect 类中删除您的 IsHighlighted 属性，您可以采用类似的方法。

希望这对您有所帮助或给您一些想法。

更新

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