c# - 创建一个 Rich Repeater，DataBind 消除自定义添加的控件

Question

所以...我有一个聪明的想法，我会创建自己的 Repeater 控件，通过继承 Repeater 并扩展它的功能来实现分页和排序。我找到了一些关于如何解决这个问题的信息和点点滴滴，一切似乎都很好......

我创建了一个 WebControlLibrary 来存放我的自定义控件。除了丰富的转发器，我还创建了一个复合控件，它可以充当“寻呼机栏”，具有前进、后退和页面选择功能。我的寻呼栏 100% 独立工作，当用户与之交互时正确触发分页更改事件。丰富的转发器数据绑定(bind)没有问题，但是当数据绑定(bind)触发时(当我调用 base.databind() 时)，控件集合被清除并且我的分页栏被删除。这搞砸了分页栏的 View 状态，使它们无法正确触发事件或保持状态。

我已经尝试在 base.databind() 触发后将控件添加回集合，但这并没有解决问题。我开始得到非常奇怪的结果，包括更改控件树层次结构的问题(通过添加 [ViewStateModeById] 解决)。

在我回到绘图板并创建第二个包含中继器和寻呼机条的复合控件(以便中继器不负责寻呼机条 View 状态)之前，是否有任何关于如何解决问题的想法？

为了共享和共享，转发器本身的代码在下面，分页条并不重要，因为问题实际上是维护任何其他子控件的状态。 (请原谅某些代码的粗糙......它仍在进行中)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

[ViewStateModeById]
public class SortablePagedRepeater : Repeater, INamingContainer {

    private SuperRepeaterPagerBar topBar = new SuperRepeaterPagerBar();
    private SuperRepeaterPagerBar btmBar = new SuperRepeaterPagerBar();

    protected override void OnInit(EventArgs e) {
        Page.RegisterRequiresControlState(this);

        InitializeControls();
        base.OnInit(e);
        EnsureChildControls();
    }

    protected void InitializeControls() {
        topBar.ID = this.ID + "__topPagerBar";
        topBar.NumberOfPages = this._currentProperties.numOfPages;
        topBar.CurrentPage = this.CurrentPageNumber;
        topBar.PageChanged +=
            new SuperRepeaterPagerBar.PageChangedEventHandler(PageChanged);

        btmBar.ID = this.ID + "__btmPagerBar";
        btmBar.NumberOfPages = this._currentProperties.numOfPages;
        btmBar.CurrentPage = this.CurrentPageNumber;
        btmBar.PageChanged +=
            new SuperRepeaterPagerBar.PageChangedEventHandler(PageChanged);
    }

    protected override void CreateChildControls() {
        EnsureDataBound();

        this.Controls.Add(topBar);
        this.Controls.Add(btmBar);
        //base.CreateChildControls();
    }

    private void PageChanged(object sender, int newPage) {
        this.CurrentPageNumber = newPage;
    }

    public override void DataBind() {
        //pageDataSource();

        //DataBind removes all controls from control collection...
        base.DataBind();
        Controls.Add(topBar);
        Controls.Add(btmBar);
    }

    private void pageDataSource() {
        //Create paged data source
        PagedDataSource pds = new PagedDataSource();

        pds.PageSize = this.ItemsPerPage;
        pds.AllowPaging = true;

        // first get a PagedDataSource going and perform sort if possible...
        if (base.DataSource is System.Collections.IEnumerable) {
            pds.DataSource = (System.Collections.IEnumerable)base.DataSource;
        } else if (base.DataSource is System.Data.DataView) {
            DataView data = (DataView)DataSource;
            if (this.SortBy != null && data.Table.Columns.Contains(this.SortBy)) {
                data.Sort = this.SortBy;
            }
            pds.DataSource = data.Table.Rows;
        } else if (base.DataSource is System.Data.DataTable) {
            DataTable data = (DataTable)DataSource;
            if (this.SortBy != null && data.Columns.Contains(this.SortBy)) {
                data.DefaultView.Sort = this.SortBy;
            }
            pds.DataSource = data.DefaultView;
        } else if (base.DataSource is System.Data.DataSet) {
            DataSet data = (DataSet)DataSource;
            if (base.DataMember != null && data.Tables.Contains(base.DataMember)) {
                if (this.SortBy != null && data.Tables[base.DataMember].Columns.Contains(this.SortBy)) {
                    data.Tables[base.DataMember].DefaultView.Sort = this.SortBy;
                }
                pds.DataSource = data.Tables[base.DataMember].DefaultView;
            } else if (data.Tables.Count > 0) {
                if (this.SortBy != null && data.Tables[0].Columns.Contains(this.SortBy)) {
                    data.Tables[0].DefaultView.Sort = this.SortBy;
                }
                pds.DataSource = data.Tables[0].DefaultView;
            } else {
                throw new Exception("DataSet doesn't have any tables.");
            }
        } else if (base.DataSource == null) {
            // don't do anything?
        } else {
            throw new Exception("DataSource must be of type System.Collections.IEnumerable.  The DataSource you provided is of type " + base.DataSource.GetType().ToString());
        }


        if (pds != null && base.DataSource != null) {
            //Make sure that the page doesn't exceed the maximum number of pages 
            //available
            if (this.CurrentPageNumber >= pds.PageCount) {
                this.CurrentPageNumber = pds.PageCount - 1;
            }

            //Set up paging values...
            btmBar.CurrentPage = topBar.CurrentPage = pds.CurrentPageIndex = this.CurrentPageNumber;
            this._currentProperties.numOfPages = btmBar.NumberOfPages = topBar.NumberOfPages = pds.PageCount;

            base.DataSource = pds;
        }
    }

    public override object DataSource {
        get {
            return base.DataSource;
        }
        set {
            //init();  //reset paging/sorting values since we've potentially changed data sources.
            base.DataSource = value;
            pageDataSource();
        }
    }

    protected override void Render(HtmlTextWriter writer) {
        topBar.RenderControl(writer);
        base.Render(writer);
        btmBar.RenderControl(writer);
    }

    [Serializable]
    protected struct CurrentProperties {
        public int pageNum;
        public int itemsPerPage;
        public int numOfPages;
        public string sortBy;
        public bool sortDir;
    }

    protected CurrentProperties _currentProperties = new CurrentProperties();

    protected override object SaveControlState() {
        return this._currentProperties;
    }

    protected override void LoadControlState(object savedState) {
        this._currentProperties = (CurrentProperties)savedState;
    }

    [Category("Status")]
    [Browsable(true)]
    [NotifyParentProperty(true)]
    [DefaultValue("")]
    [Localizable(false)]
    public string SortBy {
        get { return this._currentProperties.sortBy; }
        set {
            //If sorting by the same column, swap the sort direction.
            if (this._currentProperties.sortBy == value) {
                this.SortAscending = !this.SortAscending;
            } else {
                this.SortAscending = true;
            }
            this._currentProperties.sortBy = value;
        }
    }

    [Category("Status")]
    [Browsable(true)]
    [NotifyParentProperty(true)]
    [DefaultValue(true)]
    [Localizable(false)]
    public bool SortAscending {
        get { return this._currentProperties.sortDir; }
        set { this._currentProperties.sortDir = value; }
    }

    [Category("Status")]
    [Browsable(true)]
    [NotifyParentProperty(true)]
    [DefaultValue(25)]
    [Localizable(false)]
    public int ItemsPerPage {
        get { return this._currentProperties.itemsPerPage; }
        set { this._currentProperties.itemsPerPage = value; }
    }

    [Category("Status")]
    [Browsable(true)]
    [NotifyParentProperty(true)]
    [DefaultValue(1)]
    [Localizable(false)]
    public int CurrentPageNumber {
        get { return this._currentProperties.pageNum; }
        set { 
            this._currentProperties.pageNum = value;
            pageDataSource();
        }
    }
}

Answer 1

您还可以使用新的 ASP.NET ListView control (自 .Net 3.5 起)它具有分页/排序数据绑定(bind)和模板，这意味着您可以将它用作转发器或者非常容易地做复杂的事情，比如带有内联编辑的网格之类的显示。