CompositeDataBoundControl.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / WebControls / CompositeDataBoundControl.cs / 1 / CompositeDataBoundControl.cs
                        

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

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


    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    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) { 
                object[] dummyDataSource = new object[(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;
        }
    }
}

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