如何将自定义排序规则应用于 WPF DataGrid？
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How can I apply a custom sort rule to a WPF DataGrid?
提问by devuxer
When the user does a column sort in my DataGrid, I want all null or empty cells to be sorted to the bottom, rather than the top.
当用户在 my 中进行列排序时DataGrid，我希望将所有空单元格或空单元格排序到底部，而不是顶部。
I wrote an IComparer<T>that makes sure blanks are always sorted downward, but I can't figure out how to apply it to the columns of my DataGrid. Note that the initialsort of the DataGrid, which I'm doing with the LINQ OrderBy()method, works great. The problem is that all subsequent sorts performed by the user sort the blanks to the top.
我写了一个IComparer<T>确保空白总是向下排序的，但我不知道如何将它应用于我的DataGrid. 请注意，我使用 LINQ方法对 的初始排序效果很好。问题是用户执行的所有后续排序都将空白排序到顶部。DataGridOrderBy()
Comparer Code
比较器代码
public class BlankLastStringComparer : IComparer<string>
{
public int Compare(string x, string y)
{
if (string.IsNullOrEmpty(x) && !string.IsNullOrEmpty(y))
return 1;
else if (!string.IsNullOrEmpty(x) && string.IsNullOrEmpty(y))
return -1;
else
return string.Compare(x, y);
}
}
Questions
问题
How do I get the DataGridColumnto use my comparer? Or if this is not possible, can you offer a workaround? I'm hoping for an MVVM friendly solution if possible.
我怎样DataGridColumn才能使用我的比较器？或者，如果这是不可能的，您能否提供解决方法？如果可能，我希望有一个 MVVM 友好的解决方案。
回答by Aran Mulholland
this is how i do it : I do derive from the grid to keep all of this inside the class, so i attach to event handlers internally
这就是我的做法：我确实从网格派生以将所有这些保留在类中，因此我在内部附加到事件处理程序
attach to the sorting event
附加到排序事件
dataGrid.Sorting += new DataGridSortingEventHandler(SortHandler);
implement the method (i do this in a derived class)
实现该方法（我在派生类中执行此操作）
void SortHandler(object sender, DataGridSortingEventArgs e)
{
DataGridColumn column = e.Column;
IComparer comparer = null;
//i do some custom checking based on column to get the right comparer
//i have different comparers for different columns. I also handle the sort direction
//in my comparer
// prevent the built-in sort from sorting
e.Handled = true;
ListSortDirection direction = (column.SortDirection != ListSortDirection.Ascending) ? ListSortDirection.Ascending : ListSortDirection.Descending;
//set the sort order on the column
column.SortDirection = direction;
//use a ListCollectionView to do the sort.
ListCollectionView lcv = (ListCollectionView)CollectionViewSource.GetDefaultView(this.ItemsSource);
//this is my custom sorter it just derives from IComparer and has a few properties
//you could just apply the comparer but i needed to do a few extra bits and pieces
comparer = new ResultSort(direction);
//apply the sort
lcv.CustomSort = comparer;
}
回答by trilson86
I have an MVVM solution for this problem which makes use of attached behaviours. If you prefer to use code-behind, @Aran's solution will do the trick too.
对于这个问题，我有一个 MVVM 解决方案，它利用了附加的行为。如果您更喜欢使用代码隐藏，@Aran 的解决方案也可以解决问题。
