所以...我有一个聪明的想法,我会创建自己的 Repeater 控件,通过继承并扩展它的功能来实现分页和排序。我找到了一些信息和片段,如何去做这件事,一切都看起来不错...
我创建了一个WebControlLibrary来存放我的自定义控件。除了丰富的重复器之外,我还创建了一个组合控件,它将作为“分页栏”,具有前进、后退和页面选择功能。我的分页栏在其自身上完美地工作,当用户与之交互时适当地触发了分页更改事件。富重复器绑定数据没有问题,但当数据绑定触发时(当我调用基类的databind()时),控件集合被清除,我的分页栏都被移除了。这破坏了分页栏的视图状态,使它们无法适当地触发事件或维护其状态。
我已经尝试在base.databind()触发后重新将控件添加到集合中,但这并不能解决问题。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)。
在我重新设计并创建第二个复合控件之前,其中包含一个重复器和分页栏(这样重复器就不需要负责分页栏的视图状态),有没有什么想法来解决这个问题?
为了利益共享,中继器本身的代码如下,呼叫器栏不如问题确实是维护任何其他子控件的状态。(原谅一些代码的粗糙...它仍然是一个正在进行中的工作)
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();
}
}
}