CompositeDataBoundControl.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / Web / UI / WebControls / CompositeDataBoundControl.cs / 1305376 / CompositeDataBoundControl.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.UI.WebControls { 
 
    using System;
    using System.Collections; 

    public abstract class CompositeDataBoundControl : DataBoundControl, INamingContainer {

        internal const string ItemCountViewStateKey = "_!ItemCount"; 

 
        public override ControlCollection Controls { 
            get {
                EnsureChildControls(); 
                return base.Controls;
            }
        }
 
        /// 
        /// Overriden by DataBoundControl to determine if the control should 
        /// recreate its control hierarchy based on values in view state. 
        /// If the control hierarchy should be created, i.e. view state does
        /// exist, it calls CreateChildControls with a dummy (empty) data source 
        /// which is usable for enumeration purposes only.
        /// 
        protected internal override void CreateChildControls() {
            Controls.Clear(); 
            object controlCount = ViewState[ItemCountViewStateKey];
 
            if (controlCount == null && RequiresDataBinding) { 
                EnsureDataBound();
            } 

            if (controlCount != null && ((int)controlCount) != -1) {
                DummyDataSource dummyDataSource = new DummyDataSource((int)controlCount);
                CreateChildControls(dummyDataSource, false); 
                ClearChildViewState();
            } 
        } 

 
        /// 
        /// Performs the work of creating the control hierarchy based on a data source.
        /// When dataBinding is true, the specified data source contains real
        /// data, and the data is supposed to be pushed into the UI. 
        /// When dataBinding is false, the specified data source is a dummy data
        /// source, that allows enumerating the right number of items, but the items 
        /// themselves are null and do not contain data. In this case, the recreated 
        /// control hierarchy reinitializes its state from view state.
        /// It enables a DataBoundControl to encapsulate the logic of creating its 
        /// control hierarchy in both modes into a single code path.
        /// 
        /// 
        /// The data source to be used to enumerate items. 
        /// 
        ///  
        /// Whether the method has been called from DataBind or not. 
        /// 
        ///  
        /// The number of items created based on the data source. Put another way, its
        /// the number of items enumerated from the data source.
        /// 
        protected abstract int CreateChildControls(IEnumerable dataSource, 
                                                   bool dataBinding);
 
 
        /// 
        /// Overriden by DataBoundControl to use its properties to determine the real 
        /// data source that the control should bind to. It then clears the existing
        /// control hierarchy, and calls createChildControls to create a new control
        /// hierarchy based on the resolved data source.
        /// The implementation resolves various data source related properties to 
        /// arrive at the appropriate IEnumerable implementation to use as the real
        /// data source. 
        /// When resolving data sources, the DataSourceControlID takes highest precedence. 
        /// In this mode, DataMember is used to access the appropriate list from the
        /// DataControl. 
        /// If DataSourceControlID is not set, the value of the DataSource property is used.
        /// In this second alternative, DataMember is used to extract the appropriate
        /// list if the control has been handed an IListSource as a data source.
        ///  
        protected internal override void PerformDataBinding(IEnumerable data) {
            base.PerformDataBinding(data); 
 
            Controls.Clear();
            ClearChildViewState(); 

            TrackViewState();

            int controlCount = CreateChildControls(data, true); 
            ChildControlsCreated = true;
            ViewState[ItemCountViewStateKey] = controlCount; 
        } 
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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