WPF/MVVM：重构代码隐藏以使其为 MVVM 绑定做好准备答案

【问题标题】：WPF/MVVM: Refactoring Code-Behind to make it ready for MVVM bindingWPF/MVVM：重构代码隐藏以使其为 MVVM 绑定做好准备
【发布时间】：2011-03-08 11:04:33
【问题描述】：

我的视图的代码隐藏文件中有这段代码：

private string GetSelectedSchoolclassCode()
    {
        return ((SchoolclassCode)cboSchooclassCodeList.SelectedItem).SchoolclassCodeName;
    }

    private void dgTimeTable_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {        
        var columnNumber = dgTimeTable.CurrentCell.Column.DisplayIndex;
        var timetable = dgTimeTable.CurrentItem as TimeTableViewModel;

        switch (columnNumber)
        {
            case 0: timetable.SchoolclassCodeMonday = GetItemValue(timetable.SchoolclassCodeMonday); break;
            case 1: timetable.SchoolclassCodeTuesday = GetItemValue(timetable.SchoolclassCodeTuesday); break;
            case 2: timetable.SchoolclassCodeWednesday = GetItemValue(timetable.SchoolclassCodeWednesday); break;
            case 3: timetable.SchoolclassCodeThursday = GetItemValue(timetable.SchoolclassCodeThursday); break;
            case 4: timetable.SchoolclassCodeFriday = GetItemValue(timetable.SchoolclassCodeFriday); break;
            case 5: timetable.SchoolclassCodeSaturday = GetItemValue(timetable.SchoolclassCodeSaturday); break;
            case 6: timetable.SchoolclassCodeSunday = GetItemValue(timetable.SchoolclassCodeSunday); break;
        }
    }

    private string GetItemValue(string schoolclassCodeWeekDay)
    {
        if (schoolclassCodeWeekDay == null)
            schoolclassCodeWeekDay = GetSelectedSchoolclassCode();
        else
            schoolclassCodeWeekDay = null;

        return schoolclassCodeWeekDay;
    }

我想将所有这些代码放在 ViewModel 中。问题已经从 XAML 中的 CurrentColumn.DisplayIndex 开始。我不能用绑定声明它，因为语法是不允许的。 WPF 认为 DisplayIndex 是一个附加属性...

你会怎么做？

【问题讨论】：

“WPF 认为”是什么意思？如果你正在做绑定，你可以而且必须提供完整的路径，如果它不明显，那么 Source.没有思考。除此之外，这个开关很糟糕。枚举具有数值，可以写在一行中。

标签： wpf mvvm refactoring code-behind

【解决方案1】：

在处理诸如数据网格之类的复杂控件时，获得纯 XAML / ViewModel 分离可能会很棘手并且相当复杂。在某些情况下，最好保留一些代码来实现更简洁的 XAML 和代码。

不妨试试

private void dgTimeTable_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{        
    var columnNumber = dgTimeTable.CurrentCell.Column.DisplayIndex;
    ((YourViewModel)DataContext).SetDisplayIndex(columnNumber);
}

在你的视图模型中有其余的代码

private string GetSelectedSchoolclassCode()
{
    return ((SchoolclassCode)SelectedSchooclass).SchoolclassCodeName;
}

public int SetDisplayIndex(int columnNmber)
{        
         var timetable = CurrentItem as TimeTableViewModel;

        switch (columnNumber)
        {
            case 0: timetable.SchoolclassCodeMonday = GetItemValue(timetable.SchoolclassCodeMonday); break;
            case 1: timetable.SchoolclassCodeTuesday = GetItemValue(timetable.SchoolclassCodeTuesday); break;
            case 2: timetable.SchoolclassCodeWednesday = GetItemValue(timetable.SchoolclassCodeWednesday); break;
            case 3: timetable.SchoolclassCodeThursday = GetItemValue(timetable.SchoolclassCodeThursday); break;
            case 4: timetable.SchoolclassCodeFriday = GetItemValue(timetable.SchoolclassCodeFriday); break;
            case 5: timetable.SchoolclassCodeSaturday = GetItemValue(timetable.SchoolclassCodeSaturday); break;
            case 6: timetable.SchoolclassCodeSunday = GetItemValue(timetable.SchoolclassCodeSunday); break;
        }
    }

private string GetItemValue(string schoolclassCodeWeekDay)
{
    if (schoolclassCodeWeekDay == null)
        schoolclassCodeWeekDay = GetSelectedSchoolclassCode();
    else
        schoolclassCodeWeekDay = null;

    return schoolclassCodeWeekDay;
}

如果您将组合框绑定到 SelectedSchooclass 并将数据网格上的当前项绑定到视图模型

【讨论】：