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/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / WebControls / HierarchicalDataBoundControl.cs / 1 / HierarchicalDataBoundControl.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- namespace System.Web.UI.WebControls { using System.Collections; using System.ComponentModel; using System.Security.Permissions; using System.Web.Util; using System.Web.UI.WebControls.Adapters; [ Designer("System.Web.UI.Design.WebControls.HierarchicalDataBoundControlDesigner, " + AssemblyRef.SystemDesign) ] [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)] public abstract class HierarchicalDataBoundControl : BaseDataBoundControl { private IHierarchicalDataSource _currentHierarchicalDataSource; private bool _currentDataSourceIsFromControl; private bool _currentDataSourceValid; private bool _pagePreLoadFired; private const string DataBoundViewStateKey = "_!DataBound"; ///[IDReferenceProperty(typeof(HierarchicalDataSourceControl))] public override string DataSourceID { get { return base.DataSourceID; } set { base.DataSourceID = value; } } /// /// 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. /// 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; } ////// Gets the HierarchicalDataSourceView of the IHierarchicalDataSource /// that this control is bound to, if any. /// 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; } ////// Gets the IHierarchicalDataSource that this control is bound to, if any. /// 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(); } ////// This method is called when the IHierarchicalDataSource raises a DataSourceChanged event. /// 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; } ////// 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. /// protected internal virtual void PerformDataBinding() { } ////// Issues an asynchronous request for data to the data source using the arguments from CreateDataSourceSelectArguments. /// protected override void PerformSelect() { OnDataBinding(EventArgs.Empty); if(_adapter != null) { HierarchicalDataBoundControlAdapter hierarchicalAdapter = _adapter 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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