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//------------------------------------------------------------------------------
// <copyright file="HierarchicalDataBoundControl.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.UI.WebControls {
using System.Collections;
using System.ComponentModel;
using System.Web.Util;
using System.Web.UI.WebControls.Adapters;
[
Designer("System.Web.UI.Design.WebControls.HierarchicalDataBoundControlDesigner, " + AssemblyRef.SystemDesign)
]
public abstract class HierarchicalDataBoundControl : BaseDataBoundControl {
private IHierarchicalDataSource _currentHierarchicalDataSource;
private bool _currentDataSourceIsFromControl;
private bool _currentDataSourceValid;
private bool _pagePreLoadFired;
private const string DataBoundViewStateKey = "_!DataBound";
/// <internalonly />
[IDReferenceProperty(typeof(HierarchicalDataSourceControl))]
public override string DataSourceID {
get {
return base.DataSourceID;
}
set {
base.DataSourceID = value;
}
}
/// <devdoc>
/// Connects this hierarchical data bound control to the appropriate
/// HierarchicalDataSource and hooks up the appropriate event listener
/// for the DataSourceChanged event. The return value is the new data source
/// (if any) that was connected to. An exception is thrown if there is
/// a problem finding the requested data source.
/// </devdoc>
private IHierarchicalDataSource ConnectToHierarchicalDataSource() {
if (_currentDataSourceValid && !DesignMode) {
// Ensure that both DataSourceID as well as DataSource are not set at the same time
if (!_currentDataSourceIsFromControl && DataSourceID != null && DataSourceID.Length != 0) {
throw new InvalidOperationException(SR.GetString(SR.DataControl_MultipleDataSources, ID));
}
// If the current view is correct, there is no need to reconnect
return _currentHierarchicalDataSource;
}
// Disconnect from old view, if necessary
if ((_currentHierarchicalDataSource != null) && (_currentDataSourceIsFromControl)) {
// We only care about this event if we are bound through the DataSourceID property
_currentHierarchicalDataSource.DataSourceChanged -= new EventHandler(OnDataSourceChanged);
}
// Connect to new view
_currentHierarchicalDataSource = GetDataSource();
_currentDataSourceIsFromControl = IsBoundUsingDataSourceID;
if (_currentHierarchicalDataSource == null) {
// HierarchicalDataSource control was not found, construct a temporary data source to wrap the data
_currentHierarchicalDataSource = new ReadOnlyHierarchicalDataSource(DataSource);
}
else {
// Ensure that both DataSourceID as well as DataSource are not set at the same time
if (DataSource != null) {
throw new InvalidOperationException(SR.GetString(SR.DataControl_MultipleDataSources, ID));
}
}
_currentDataSourceValid = true;
if ((_currentHierarchicalDataSource != null) && (_currentDataSourceIsFromControl)) {
// We only care about this event if we are bound through the DataSourceID property
_currentHierarchicalDataSource.DataSourceChanged += new EventHandler(OnDataSourceChanged);
}
return _currentHierarchicalDataSource;
}
/// <devdoc>
/// Gets the HierarchicalDataSourceView of the IHierarchicalDataSource
/// that this control is bound to, if any.
/// </devdoc>
protected virtual HierarchicalDataSourceView GetData(string viewPath) {
string currentViewPath = viewPath;
IHierarchicalDataSource ds = ConnectToHierarchicalDataSource();
Debug.Assert(_currentDataSourceValid);
Debug.Assert(ds != null);
// IHierarchicalDataSource was found, extract the appropriate view and return it
HierarchicalDataSourceView view = ds.GetHierarchicalView(currentViewPath);
if (view == null) {
throw new InvalidOperationException(SR.GetString(SR.HierarchicalDataControl_ViewNotFound, ID));
}
return view;
}
/// <devdoc>
/// Gets the IHierarchicalDataSource that this control is bound to, if any.
/// </devdoc>
protected virtual IHierarchicalDataSource GetDataSource() {
if (!DesignMode && _currentDataSourceValid && (_currentHierarchicalDataSource != null)) {
return _currentHierarchicalDataSource;
}
IHierarchicalDataSource ds = null;
string dataSourceID = DataSourceID;
if (dataSourceID.Length != 0) {
// Try to find a DataSource control with the ID specified in DataSourceID
Control control = DataBoundControlHelper.FindControl(this, dataSourceID);
if (control == null) {
throw new HttpException(SR.GetString(SR.HierarchicalDataControl_DataSourceDoesntExist, ID, dataSourceID));
}
ds = control as IHierarchicalDataSource;
if (ds == null) {
throw new HttpException(SR.GetString(SR.HierarchicalDataControl_DataSourceIDMustBeHierarchicalDataControl, ID, dataSourceID));
}
}
return ds;
}
protected void MarkAsDataBound() {
ViewState[DataBoundViewStateKey] = true;
}
protected override void OnDataPropertyChanged() {
_currentDataSourceValid = false;
base.OnDataPropertyChanged();
}
/// <devdoc>
/// This method is called when the IHierarchicalDataSource raises a DataSourceChanged event.
/// </devdoc>
protected virtual void OnDataSourceChanged(object sender, EventArgs e) {
RequiresDataBinding = true;
}
protected internal override void OnLoad(EventArgs e) {
ConfirmInitState();
ConnectToHierarchicalDataSource();
if (Page != null && !_pagePreLoadFired && ViewState[DataBoundViewStateKey] == null) {
// If the control was added after PagePreLoad, we still need to databind it because it missed its
// first change in PagePreLoad. If this control was created by a call to a parent control's DataBind
// in Page_Load (with is relatively common), this control will already have been databound even
// though pagePreLoad never fired and the page isn't a postback.
if (!Page.IsPostBack) {
RequiresDataBinding = true;
}
// If the control was added to the page after page.PreLoad, we'll never get the event and we'll
// never databind the control. So if we're catching up and Load happens but PreLoad never happened,
// call DataBind. This may make the control get databound twice if the user called DataBind on the control
// directly in Page.OnLoad, but better to bind twice than never to bind at all.
else if (IsViewStateEnabled) {
RequiresDataBinding = true;
}
}
base.OnLoad(e);
}
protected override void OnPagePreLoad(object sender, EventArgs e) {
base.OnPagePreLoad(sender, e);
if (Page != null) {
// Setting RequiresDataBinding to true in OnLoad is too late because the OnLoad page event
// happens before the control.OnLoad method gets called. So a page_load handler on the page
// that calls DataBind won't prevent DataBind from getting called again in PreRender.
if (!Page.IsPostBack) {
RequiresDataBinding = true;
}
// If this is a postback and viewstate is enabled, but we have never bound the control
// before, it is probably because its visibility was changed in the postback. In this
// case, we need to bind the control or it will never appear. This is a common scenario
// for Wizard and MultiView.
else if (IsViewStateEnabled && ViewState[DataBoundViewStateKey] == null) {
RequiresDataBinding = true;
}
}
_pagePreLoadFired = true;
}
/// <devdoc>
/// This method should be overridden by databound controls to perform their databinding.
/// Overriding this method instead of DataBind() will allow the DataBound control developer
/// to not worry about DataBinding events to be called in the right order.
/// </devdoc>
protected internal virtual void PerformDataBinding() {
}
/// <summary>
/// Issues an asynchronous request for data to the data source using the arguments from CreateDataSourceSelectArguments.
/// </summary>
protected override void PerformSelect() {
OnDataBinding(EventArgs.Empty);
if (AdapterInternal != null) {
HierarchicalDataBoundControlAdapter hierarchicalAdapter = AdapterInternal as HierarchicalDataBoundControlAdapter;
if(hierarchicalAdapter != null) {
hierarchicalAdapter.PerformDataBinding();
}
else {
PerformDataBinding();
}
}
else {
PerformDataBinding();
}
RequiresDataBinding = false;
MarkAsDataBound();
OnDataBound(EventArgs.Empty);
}
protected override void ValidateDataSource(object dataSource) {
if ((dataSource == null) ||
(dataSource is IHierarchicalEnumerable) ||
(dataSource is IHierarchicalDataSource)) {
return;
}
throw new InvalidOperationException(SR.GetString(SR.HierarchicalDataBoundControl_InvalidDataSource));
}
}
}
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