c# -排序数据视图的麻烦

本文关键字:麻烦 视图 数据 排序 | 更新日期: 2023-09-27 18:12:59

我拼命寻找问题的答案。我用几个datagridviews开发了一个c# Winforms程序。

问题是,我想成为用户能够排序的数据视图通过点击列标题(我认为这将是标准的…)但就是行不通。

我试了dgv。排序方法,但这会抛出一个异常,datagridview必须绑定到一个IBindingList,但我不知道如何做到这一点,我真的不想重新开发一切。

这是我如何填充我的dgv。

我有一些自定义对象,并将它们放入列表中。当这个列表被完全填充后,我将它设置为dgv的数据源。

list.Add(costumobject);
.
.
.
dgv.DataSource = list;

你能告诉我一个快速使排序函数工作的方法吗?

亲切的问候,

c# -排序数据视图的麻烦

DataGridView本身不会在内部对其行进行排序。相反,它利用附加数据源的排序功能,如果数据源不提供排序功能,则DataGridView列排序也不可用。

创建一个SortableBindingList,并使用它代替List。

using System;
using System.Collections.Generic;
using System.ComponentModel;
namespace YourNamespace
{
    /// <summary>
    /// Provides a generic collection that supports data binding and additionally supports sorting.
    /// See http://msdn.microsoft.com/en-us/library/ms993236.aspx
    /// If the elements are IComparable it uses that; otherwise compares the ToString()
    /// </summary>
    /// <typeparam name="T">The type of elements in the list.</typeparam>
    public class SortableBindingList<T> : BindingList<T> where T : class
    {
        private bool _isSorted;
        private ListSortDirection _sortDirection = ListSortDirection.Ascending;
        private PropertyDescriptor _sortProperty;
        /// <summary>
        /// Initializes a new instance of the <see cref="SortableBindingList{T}"/> class.
        /// </summary>
        public SortableBindingList()
        {
        }
        /// <summary>
        /// Initializes a new instance of the <see cref="SortableBindingList{T}"/> class.
        /// </summary>
        /// <param name="list">An <see cref="T:System.Collections.Generic.IList`1" /> of items to be contained in the <see cref="T:System.ComponentModel.BindingList`1" />.</param>
        public SortableBindingList(IList<T> list) : base(list)
        {
        }
        /// <summary>
        /// Gets a value indicating whether the list supports sorting.
        /// </summary>
        protected override bool SupportsSortingCore
        {
            get { return true; }
        }
        /// <summary>
        /// Gets a value indicating whether the list is sorted.
        /// </summary>
        protected override bool IsSortedCore
        {
            get { return _isSorted; }
        }
        /// <summary>
        /// Gets the direction the list is sorted.
        /// </summary>
        protected override ListSortDirection SortDirectionCore
        {
            get { return _sortDirection; }
        }
        /// <summary>
        /// Gets the property descriptor that is used for sorting the list if sorting is implemented in a derived class; otherwise, returns null
        /// </summary>
        protected override PropertyDescriptor SortPropertyCore
        {
            get { return _sortProperty; }
        }
        /// <summary>
        /// Removes any sort applied with ApplySortCore if sorting is implemented
        /// </summary>
        protected override void RemoveSortCore()
        {
            _sortDirection = ListSortDirection.Ascending;
            _sortProperty = null;
            _isSorted = false; //thanks Luca
        }
        /// <summary>
        /// Sorts the items if overridden in a derived class
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="direction"></param>
        protected override void ApplySortCore(PropertyDescriptor prop, ListSortDirection direction)
        {
            _sortProperty = prop;
            _sortDirection = direction;
            List<T> list = Items as List<T>;
            if (list == null) return;
            list.Sort(Compare);
            _isSorted = true;
            //fire an event that the list has been changed.
            OnListChanged(new ListChangedEventArgs(ListChangedType.Reset, -1));
        }
        private int Compare(T lhs, T rhs)
        {
            var result = OnComparison(lhs, rhs);
            //invert if descending
            if (_sortDirection == ListSortDirection.Descending)
                result = -result;
            return result;
        }
        private int OnComparison(T lhs, T rhs)
        {
            object lhsValue = lhs == null ? null : _sortProperty.GetValue(lhs);
            object rhsValue = rhs == null ? null : _sortProperty.GetValue(rhs);
            if (lhsValue == null)
            {
                return (rhsValue == null) ? 0 : -1; //nulls are equal
            }
            if (rhsValue == null)
            {
                return 1; //first has value, second doesn't
            }
            if (lhsValue is IComparable)
            {
                return ((IComparable)lhsValue).CompareTo(rhsValue);
            }
            if (lhsValue.Equals(rhsValue))
            {
                return 0; //both are the same
            }
            //not comparable, compare ToString
            return lhsValue.ToString().CompareTo(rhsValue.ToString());
        }
    }
}

List<T>不支持直接排序。

您可以使用Linq例程来进行排序。

但是,您需要包含一个排序字段检查,它将与您的列数一样长。

不知道你的customobject类,让我们尝试Name类:

class Name
{
    public string first { get; set; }
    public string last { get; set; }
    public string middle { get; set; }
    public Name (string f, string m, string l)
    {
        first = f; middle = m; last = l;
    }
}

现在让我们编写ColumnHeaderMouseClick事件:

private void dataGridView1_ColumnHeaderMouseClick(object sender, 
                           DataGridViewCellMouseEventArgs e)
{
    List<Name> names = dataGridView1.DataSource as List<Name>;
    string col = dataGridView2.Columns[e.ColumnIndex].DataPropertyName;
    string order =  " ASC";
    if (dataGridView1.Tag != null) 
        order = dataGridView1.Tag.ToString().Contains(" ASC") ? " DESC" : " ASC";
    dataGridView1.Tag = col + order;
    if (order.Contains(" ASC"))
    names = names.OrderBy(x => col == "first"? x.first 
                             : col == "last" ? x.last : x.middle).ToList();  
    else
    names = names.OrderByDescending(x => col == "first"? x.first : 
                                         col == "last" ? x.last : x.middle).ToList();  
    dataGridView1.DataSource = names;
}

请注意,我将当前排序列和顺序存储在DGV的Tag中。您可以将其移动到类级别变量或其他位置。不幸的是,DGV的SortOrder属性不能设置…

您是否尝试在更改数据源后刷新数据网格?

list.Add(costumobject);
.
.
.
dgv.DataSource = list;
dgv.Refresh();