ObjectDataSource.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / WebControls / ObjectDataSource.cs / 1 / ObjectDataSource.cs

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

namespace System.Web.UI.WebControls { 
 
    using System;
    using System.Collections; 
    using System.ComponentModel;
    using System.Drawing;
    using System.Drawing.Design;
    using System.Globalization; 
    using System.Security.Permissions;
    using System.Text; 
    using System.Web.Caching; 
    using System.Web.UI;
 

    /// 
    /// Represents a data source that calls methods on a business object in order to
    /// perform the Delete, Insert, Select, and Update operations. The business object 
    /// is specified in the TypeName property.
    ///  
    [ 
    DefaultEvent("Selecting"),
    DefaultProperty("TypeName"), 
    Designer("System.Web.UI.Design.WebControls.ObjectDataSourceDesigner, " + AssemblyRef.SystemDesign),
    ParseChildren(true),
    PersistChildren(false),
    ToolboxBitmap(typeof(ObjectDataSource)), 
    WebSysDescription(SR.ObjectDataSource_Description),
    WebSysDisplayName(SR.ObjectDataSource_DisplayName) 
    ] 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public class ObjectDataSource : DataSourceControl {

        private const string DefaultViewName = "DefaultView";
 
        private SqlDataSourceCache _cache;
        private ObjectDataSourceView _view; 
        private ICollection _viewNames; 

 

        /// 
        /// Creates a new instance of ObjectDataSource.
        ///  
        public ObjectDataSource() {
        } 
 

        ///  
        /// Creates a new instance of ObjectDataSource with a specified type name and select method.
        /// 
        public ObjectDataSource(string typeName, string selectMethod) {
            TypeName = typeName; 
            SelectMethod = selectMethod;
        } 
 

 
        /// 
        /// Specifies the cache settings for this data source. For the cache to
        /// work, the SelectMethod must return a DataSet.
        ///  
        internal SqlDataSourceCache Cache {
            get { 
                if (_cache == null) { 
                    _cache = new SqlDataSourceCache();
                } 
                return _cache;
            }
        }
 

        ///  
        /// The duration, in seconds, of the expiration. The expiration policy is specified by the CacheExpirationPolicy property. 
        /// 
        [ 
        DefaultValue(DataSourceCache.Infinite),
        TypeConverterAttribute(typeof(DataSourceCacheDurationConverter)),
        WebCategory("Cache"),
        WebSysDescription(SR.DataSourceCache_Duration), 
        ]
        public virtual int CacheDuration { 
            get { 
                return Cache.Duration;
            } 
            set {
                Cache.Duration = value;
            }
        } 

 
        ///  
        /// The expiration policy of the cache. The duration for the expiration is specified by the CacheDuration property.
        ///  
        [
        DefaultValue(DataSourceCacheExpiry.Absolute),
        WebCategory("Cache"),
        WebSysDescription(SR.DataSourceCache_ExpirationPolicy), 
        ]
        public virtual DataSourceCacheExpiry CacheExpirationPolicy { 
            get { 
                return Cache.ExpirationPolicy;
            } 
            set {
                Cache.ExpirationPolicy = value;
            }
        } 

 
        ///  
        /// Indicates an arbitrary cache key to make this cache entry depend on. This allows
        /// the user to further customize when this cache entry will expire. 
        /// 
        [
        DefaultValue(""),
        WebCategory("Cache"), 
        WebSysDescription(SR.DataSourceCache_KeyDependency),
        ] 
        public virtual string CacheKeyDependency { 
            get {
                return Cache.KeyDependency; 
            }
            set {
                Cache.KeyDependency = value;
            } 
        }
 
        ///  
        /// Whether the commands pass old values in the parameter collection.
        ///  
        [
        DefaultValue(ConflictOptions.OverwriteChanges),
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_ConflictDetection), 
        ]
        public ConflictOptions ConflictDetection { 
            get { 
                return GetView().ConflictDetection;
            } 
            set {
                GetView().ConflictDetection = value;
            }
        } 

        ///  
        /// Whether null values passed into insert/update/delete operations 
        /// will be converted to System.DbNull.
        ///  
        [
        DefaultValue(false),
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_ConvertNullToDBNull), 
        ]
        public bool ConvertNullToDBNull { 
            get { 
                return GetView().ConvertNullToDBNull;
            } 
            set {
                GetView().ConvertNullToDBNull = value;
            }
        } 

 
        ///  
        /// An optional type that is used for update, insert, and delete
        /// scenarios where the object's methods take in an aggregate object 
        /// rather than one parameter for each property in the selected data.
        /// 
        [
        DefaultValue(""), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_DataObjectTypeName), 
        ] 
        public string DataObjectTypeName {
            get { 
                return GetView().DataObjectTypeName;
            }
            set {
                GetView().DataObjectTypeName = value; 
            }
        } 
 

        ///  
        /// The method to execute when Delete() is called.
        /// 
        [
        DefaultValue(""), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_DeleteMethod), 
        ] 
        public string DeleteMethod {
            get { 
                return GetView().DeleteMethod;
            }
            set {
                GetView().DeleteMethod = value; 
            }
        } 
 
        /// 
        // Collection of parameters used when calling the DeleteMethod. These parameters are merged with the parameters provided by data-bound controls. 

        /// 
        [
        DefaultValue(null), 
        Editor("System.Web.UI.Design.WebControls.ParameterCollectionEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)),
        MergableProperty(false), 
        PersistenceMode(PersistenceMode.InnerProperty), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_DeleteParameters), 
        ]
        public ParameterCollection DeleteParameters {
            get {
                return GetView().DeleteParameters; 
            }
        } 
 

        ///  
        /// Whether caching is enabled for this data source.
        /// 
        [
        DefaultValue(false), 
        WebCategory("Cache"),
        WebSysDescription(SR.DataSourceCache_Enabled), 
        ] 
        public virtual bool EnableCaching {
            get { 
                return Cache.Enabled;
            }
            set {
                Cache.Enabled = value; 
            }
        } 
 
        /// 
        /// Indicates whether the Select method supports paging. If this is set to true, the 
        /// StartRowIndexParameterName and MaximumRowsParameterName properties must be set to the
        /// names of the parameters of the Select method that accept the values for the starting
        /// record to retrieve and the number of records to retrieve.
        ///  
        [
        DefaultValue(false), 
        WebCategory("Paging"), 
        WebSysDescription(SR.ObjectDataSource_EnablePaging),
        ] 
        public bool EnablePaging {
            get {
                return GetView().EnablePaging;
            } 
            set {
                GetView().EnablePaging = value; 
            } 
        }
 

        /// 
        /// Filter expression used when Select() is called. Filtering is only available when the SelectMethod returns a DataSet.
        ///  
        [
        DefaultValue(""), 
        WebCategory("Data"), 
        WebSysDescription(SR.ObjectDataSource_FilterExpression),
        ] 
        public string FilterExpression {
            get {
                return GetView().FilterExpression;
            } 
            set {
                GetView().FilterExpression = value; 
            } 
        }
 

        /// 
        /// Collection of parameters used in the FilterExpression property. Filtering is only available when the SelectMethod returns a DataSet.
        ///  
        [
        DefaultValue(null), 
        Editor("System.Web.UI.Design.WebControls.ParameterCollectionEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)), 
        MergableProperty(false),
        PersistenceMode(PersistenceMode.InnerProperty), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_FilterParameters),
        ]
        public ParameterCollection FilterParameters { 
            get {
                return GetView().FilterParameters; 
            } 
        }
 

        /// 
        /// The method to execute when Insert() is called.
        ///  
        [
        DefaultValue(""), 
        WebCategory("Data"), 
        WebSysDescription(SR.ObjectDataSource_InsertMethod),
        ] 
        public string InsertMethod {
            get {
                return GetView().InsertMethod;
            } 
            set {
                GetView().InsertMethod = value; 
            } 
        }
 

        /// 
        /// Collection of values used when calling the InsertMethod. These parameters are merged with the parameters provided by data-bound controls.
        ///  
        [
        DefaultValue(null), 
        Editor("System.Web.UI.Design.WebControls.ParameterCollectionEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)), 
        MergableProperty(false),
        PersistenceMode(PersistenceMode.InnerProperty), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_InsertParameters),
        ]
        public ParameterCollection InsertParameters { 
            get {
                return GetView().InsertParameters; 
            } 
        }
 
        /// 
        /// When EnablePaging is set to true, this property indicates the parameter of the Select
        /// method that accepts the value for the number of records to retrieve.
        ///  
        [
        DefaultValue("maximumRows"), 
        WebCategory("Paging"), 
        WebSysDescription(SR.ObjectDataSource_MaximumRowsParameterName),
        ] 
        public string MaximumRowsParameterName {
            get {
                return GetView().MaximumRowsParameterName;
            } 
            set {
                GetView().MaximumRowsParameterName = value; 
            } 
        }
 
        /// 
        /// The format string applied to the names of the old values parameters
        /// 
        [ 
        DefaultValue("{0}"),
        WebCategory("Data"), 
        WebSysDescription(SR.DataSource_OldValuesParameterFormatString), 
        ]
        public string OldValuesParameterFormatString { 
            get {
                return GetView().OldValuesParameterFormatString;
            }
            set { 
                GetView().OldValuesParameterFormatString = value;
            } 
        } 

        ///  
        /// The command to execute when Select is called on the ObjectDataSourceView, requesting the total number of rows.
        /// 
        [
        DefaultValue(""), 
        WebCategory("Paging"),
        WebSysDescription(SR.ObjectDataSource_SelectCountMethod), 
        ] 
        public string SelectCountMethod {
            get { 
                return GetView().SelectCountMethod;
            }
            set {
                GetView().SelectCountMethod = value; 
            }
        } 
 

        ///  
        /// The method to execute when Select() is called.
        /// 
        [
        DefaultValue(""), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_SelectMethod), 
        ] 
        public string SelectMethod {
            get { 
                return GetView().SelectMethod;
            }
            set {
                GetView().SelectMethod = value; 
            }
        } 
 

        ///  
        /// Collection of parameters used when calling the SelectMethod.
        /// 
        [
        DefaultValue(null), 
        Editor("System.Web.UI.Design.WebControls.ParameterCollectionEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)),
        MergableProperty(false), 
        PersistenceMode(PersistenceMode.InnerProperty), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_SelectParameters), 
        ]
        public ParameterCollection SelectParameters {
            get {
                return GetView().SelectParameters; 
            }
        } 
 

        ///  
        /// The name of the parameter in the SelectMethod that specifies the
        /// sort expression. This parameter's value will be automatically set
        /// at runtime with the appropriate sort expression.
        ///  
        [
        DefaultValue(""), 
        WebCategory("Data"), 
        WebSysDescription(SR.ObjectDataSource_SortParameterName),
        ] 
        public string SortParameterName {
            get {
                return GetView().SortParameterName;
            } 
            set {
                GetView().SortParameterName = value; 
            } 
        }
 

        /// 
        /// A semi-colon delimited string indicating which databases to use for the dependency in the format "database1:table1;database2:table2".
        ///  
        [
        DefaultValue(""), 
        WebCategory("Cache"), 
        WebSysDescription(SR.SqlDataSourceCache_SqlCacheDependency),
        ] 
        public virtual string SqlCacheDependency {
            get {
                return Cache.SqlCacheDependency;
 
            }
            set { 
                Cache.SqlCacheDependency = value; 
            }
        } 

        /// 
        /// When EnablePaging is set to true, this property indicates the parameter of the Select
        /// method that accepts the value for the number of first record to retrieve. 
        /// 
        [ 
        DefaultValue("startRowIndex"), 
        WebCategory("Paging"),
        WebSysDescription(SR.ObjectDataSource_StartRowIndexParameterName), 
        ]
        public string StartRowIndexParameterName {
            get {
                return GetView().StartRowIndexParameterName; 
            }
            set { 
                GetView().StartRowIndexParameterName = value; 
            }
        } 


        /// 
        /// The type that contains the methods specified in this control. 
        /// 
        [ 
        DefaultValue(""), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_TypeName), 
        ]
        public string TypeName {
            get {
                return GetView().TypeName; 
            }
            set { 
                GetView().TypeName = value; 
            }
        } 


        /// 
        /// The method to execute when Update() is called. 
        /// 
        [ 
        DefaultValue(""), 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_UpdateMethod), 
        ]
        public string UpdateMethod {
            get {
                return GetView().UpdateMethod; 
            }
            set { 
                GetView().UpdateMethod = value; 
            }
        } 


        /// 
        /// Collection of parameters and values used when calling the UpdateMethod. These parameters are merged with the parameters provided by data-bound controls. 
        /// 
        [ 
        DefaultValue(null), 
        Editor("System.Web.UI.Design.WebControls.ParameterCollectionEditor, " + AssemblyRef.SystemDesign, typeof(UITypeEditor)),
        MergableProperty(false), 
        PersistenceMode(PersistenceMode.InnerProperty),
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_UpdateParameters),
        ] 
        public ParameterCollection UpdateParameters {
            get { 
                return GetView().UpdateParameters; 
            }
        } 



        ///  
        /// This event is raised after the Delete operation has completed.
        /// Handle this event if you need to examine the return values of 
        /// the method call, or examine an exception that may have been thrown. 
        /// 
        [ 
        WebCategory("Data"),
        WebSysDescription(SR.DataSource_Deleted),
        ]
        public event ObjectDataSourceStatusEventHandler Deleted { 
            add {
                GetView().Deleted += value; 
            } 
            remove {
                GetView().Deleted -= value; 
            }
        }

 
        /// 
        /// This event is raised before the Delete operation has been executed. 
        /// Handle this event if you need to validate the values of parameters or 
        /// change their values.
        ///  
        [
        WebCategory("Data"),
        WebSysDescription(SR.DataSource_Deleting),
        ] 
        public event ObjectDataSourceMethodEventHandler Deleting {
            add { 
                GetView().Deleting += value; 
            }
            remove { 
                GetView().Deleting -= value;
            }
        }
 
        /// 
        /// This event is raised before the Filter operation takes place. 
        /// Handle this event if you want to perform validation operations on 
        /// the parameter values. This event is only raised if the FilterExpression
        /// is set. If the Cancel property of the event arguments is set to true, 
        /// the Select operation is aborted and the operation will return null.
        /// 
        [
        WebCategory("Data"), 
        WebSysDescription(SR.DataSource_Filtering),
        ] 
        public event ObjectDataSourceFilteringEventHandler Filtering { 
            add {
                GetView().Filtering += value; 
            }
            remove {
                GetView().Filtering -= value;
            } 
        }
 
 
        /// 
        /// This event is raised after the Insert operation has completed. 
        /// Handle this event if you need to examine the return values of
        /// the method call, or examine an exception that may have been thrown.
        /// 
        [ 
        WebCategory("Data"),
        WebSysDescription(SR.DataSource_Inserted), 
        ] 
        public event ObjectDataSourceStatusEventHandler Inserted {
            add { 
                GetView().Inserted += value;
            }
            remove {
                GetView().Inserted -= value; 
            }
        } 
 

        ///  
        /// This event is raised before the Insert operation has been executed.
        /// Handle this event if you need to validate the values of parameters or
        /// change their values.
        ///  
        [
        WebCategory("Data"), 
        WebSysDescription(SR.DataSource_Inserting), 
        ]
        public event ObjectDataSourceMethodEventHandler Inserting { 
            add {
                GetView().Inserting += value;
            }
            remove { 
                GetView().Inserting -= value;
            } 
        } 

 
        /// 
        /// This event is raised after the instance of the object has been created.
        /// Handle this event if you need to set additional properties on the
        /// object before any other methods are called. This event will not be 
        /// raised if a custom instance was provided in the ObjectCreating event.
        ///  
        [ 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_ObjectCreated), 
        ]
        public event ObjectDataSourceObjectEventHandler ObjectCreated {
            add {
                GetView().ObjectCreated += value; 
            }
            remove { 
                GetView().ObjectCreated -= value; 
            }
        } 


        /// 
        /// This event is raised before the instance of the object has been created. 
        /// Handle this event if you need to call a non-default constructor on the
        /// object. Set the ObjectInstance property of the EventArgs with the 
        /// custom instance. If this is set, the ObjectCreated event will not be 
        /// raised.
        ///  
        [
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_ObjectCreating),
        ] 
        public event ObjectDataSourceObjectEventHandler ObjectCreating {
            add { 
                GetView().ObjectCreating += value; 
            }
            remove { 
                GetView().ObjectCreating -= value;
            }
        }
 

        ///  
        /// This event is raised before the instance of the object is disposed. 
        /// Handle this event if you need to retrieve properties on the
        /// object before it is disposed. If the object implements the IDispoable 
        /// interface, then the Dispose() method will be called automatically.
        /// Set the Cancel property of the event args to true if you do not want
        /// IDisposable.Dispose() to be called automatically.
        ///  
        [
        WebCategory("Data"), 
        WebSysDescription(SR.ObjectDataSource_ObjectDisposing), 
        ]
        public event ObjectDataSourceDisposingEventHandler ObjectDisposing { 
            add {
                GetView().ObjectDisposing += value;
            }
            remove { 
                GetView().ObjectDisposing -= value;
            } 
        } 

 
        /// 
        /// This event is raised after the Select operation has completed.
        /// Handle this event if you need to examine the return values of
        /// the method call, or examine an exception that may have been thrown. 
        /// 
        [ 
        WebCategory("Data"), 
        WebSysDescription(SR.ObjectDataSource_Selected),
        ] 
        public event ObjectDataSourceStatusEventHandler Selected {
            add {
                GetView().Selected += value;
            } 
            remove {
                GetView().Selected -= value; 
            } 
        }
 

        /// 
        /// This event is raised before the Select operation has been executed.
        /// Handle this event if you need to validate the values of parameters or 
        /// change their values.
        ///  
        [ 
        WebCategory("Data"),
        WebSysDescription(SR.ObjectDataSource_Selecting), 
        ]
        public event ObjectDataSourceSelectingEventHandler Selecting {
            add {
                GetView().Selecting += value; 
            }
            remove { 
                GetView().Selecting -= value; 
            }
        } 


        /// 
        /// This event is raised after the Update operation has completed. 
        /// Handle this event if you need to examine the return values of
        /// the method call, or examine an exception that may have been thrown. 
        ///  
        [
        WebCategory("Data"), 
        WebSysDescription(SR.DataSource_Updated),
        ]
        public event ObjectDataSourceStatusEventHandler Updated {
            add { 
                GetView().Updated += value;
            } 
            remove { 
                GetView().Updated -= value;
            } 
        }


        ///  
        /// This event is raised before the Update operation has been executed.
        /// Handle this event if you need to validate the values of parameters or 
        /// change their values. 
        /// 
        [ 
        WebCategory("Data"),
        WebSysDescription(SR.DataSource_Updating),
        ]
        public event ObjectDataSourceMethodEventHandler Updating { 
            add {
                GetView().Updating += value; 
            } 
            remove {
                GetView().Updating -= value; 
            }
        }

 
        /// 
        /// Creates a unique cache key for this data source's data. 
        ///  
        internal string CreateCacheKey(int startRowIndex, int maximumRows) {
            StringBuilder sb = CreateRawCacheKey(); 

            sb.Append(':');
            sb.Append(startRowIndex.ToString(CultureInfo.InvariantCulture));
            sb.Append(':'); 
            sb.Append(maximumRows.ToString(CultureInfo.InvariantCulture));
 
            return sb.ToString(); 
        }
 
        /// 
        /// Creates the cache key for the master (parent) cache entry, which holds the total row count.
        /// 
        internal string CreateMasterCacheKey() { 
            return CreateRawCacheKey().ToString();
        } 
 
        /// 
        /// Returns the string for the raw (unhashed) master cache key. 
        /// 
        private StringBuilder CreateRawCacheKey() {
            // Note: The cache key will contain information such as type names and
            // method names, however it will be stored in the internal cache, which is 
            // not accessible to page developers, so it is secure.
            StringBuilder sb = new StringBuilder(CacheInternal.PrefixDataSourceControl, 1024); 
            sb.Append(GetType().GetHashCode().ToString(CultureInfo.InvariantCulture)); 
            sb.Append(":");
            sb.Append(CacheDuration.ToString(CultureInfo.InvariantCulture)); 
            sb.Append(':');
            sb.Append(((int)CacheExpirationPolicy).ToString(CultureInfo.InvariantCulture));
            sb.Append(":");
            sb.Append(SqlCacheDependency); 
            sb.Append(":");
            sb.Append(TypeName); 
            sb.Append(":"); 
            sb.Append(SelectMethod);
 
            // Append parameter names and values
            if (SelectParameters.Count > 0) {
                sb.Append("?");
                IDictionary parameters = SelectParameters.GetValues(Context, this); 
                foreach (DictionaryEntry entry in parameters) {
                    sb.Append(entry.Key.ToString()); 
                    if ((entry.Value != null) && (entry.Value != DBNull.Value)) { 
                        sb.Append("=");
                        sb.Append(entry.Value.ToString()); 
                    }
                    else {
                        if (entry.Value == DBNull.Value) {
                            sb.Append("(dbnull)"); 
                        }
                        else { 
                            sb.Append("(null)"); 
                        }
                    } 
                    sb.Append("&");
                }
            }
            return sb; 
        }
 
 
        /// 
        /// Deletes rows from the data source using the parameters specified in the DeleteParameters collection. 
        /// 
        public int Delete() {
            return GetView().Delete(null, null);
        } 

        ///  
        /// Dynamically creates the default (and only) ObjectDataSourceView on demand. 
        /// 
        private ObjectDataSourceView GetView() { 
            if (_view == null) {
                _view = new ObjectDataSourceView(this, DefaultViewName, Context);

                if (IsTrackingViewState) { 
                    ((IStateManager)_view).TrackViewState();
                } 
            } 

            return _view; 
        }


        ///  
        /// Gets the view associated with this data source.
        ///  
        protected override DataSourceView GetView(string viewName) { 
            if (viewName == null || (viewName.Length != 0 && !String.Equals(viewName, DefaultViewName, StringComparison.OrdinalIgnoreCase))) {
                throw new ArgumentException(SR.GetString(SR.DataSource_InvalidViewName, ID, DefaultViewName), "viewName"); 
            }

            return GetView();
        } 

 
        ///  
        /// 
        protected override ICollection GetViewNames() { 
            if (_viewNames == null) {
                _viewNames = new string[1] { DefaultViewName };
            }
            return _viewNames; 
        }
 
 
        /// 
        /// Inserts a new row with names and values specified the InsertValues collection. 
        /// 
        public int Insert() {
            return GetView().Insert(null);
        } 

        ///  
        /// Invalidates a cache entry. 
        /// 
        internal void InvalidateCacheEntry() { 
            string key = CreateMasterCacheKey();
            Cache.Invalidate(key);
        }
 
        /// 
        /// Event handler for the Page's LoadComplete event. 
        /// Updates the parameters' values to possibly raise a DataSourceViewChanged event, causing bound controls to re-databind. 
        /// 
        private void LoadCompleteEventHandler(object sender, EventArgs e) { 
            SelectParameters.UpdateValues(Context, this);
            FilterParameters.UpdateValues(Context, this);
        }
 
        /// 
        /// Loads data from the cache. 
        ///  
        internal object LoadDataFromCache(int startRowIndex, int maximumRows) {
            string key = CreateCacheKey(startRowIndex, maximumRows); 
            return Cache.LoadDataFromCache(key);
        }

        ///  
        /// Loads data from the cache.
        ///  
        internal int LoadTotalRowCountFromCache() { 
            string key = CreateMasterCacheKey();
            object data = Cache.LoadDataFromCache(key); 
            if (data is int)
                return (int)data;
            return -1;
        } 

 
        ///  
        /// Loads view state.
        ///  
        protected override void LoadViewState(object savedState) {
            Pair myState = (Pair)savedState;

            if (savedState == null) { 
                base.LoadViewState(null);
            } 
            else { 
                base.LoadViewState(myState.First);
 
                if (myState.Second != null) {
                    ((IStateManager)GetView()).LoadViewState(myState.Second);
                }
            } 
        }
 
 
        /// 
        /// Adds LoadComplete event handler to the page. 
        /// 
        protected internal override void OnInit(EventArgs e) {
            base.OnInit(e);
 
            if (Page != null) {
                Page.LoadComplete += new EventHandler(LoadCompleteEventHandler); 
            } 
        }
 
        /// 
        /// Saves paged data to cache, creating a dependency on the updated row count
        /// 
        internal void SaveDataToCache(int startRowIndex, int maximumRows, object data) { 
            string key = CreateCacheKey(startRowIndex, maximumRows);
            string parentKey = CreateMasterCacheKey(); 
            if (Cache.LoadDataFromCache(parentKey) == null) { 
                Cache.SaveDataToCache(parentKey, -1);
            } 
            CacheDependency cacheDependency = new CacheDependency(0, new string[0], new string[] { parentKey });
            Cache.SaveDataToCache(key, data, cacheDependency);
        }
 
        /// 
        /// Saves the total row count to cache. 
        ///  
        internal void SaveTotalRowCountToCache(int totalRowCount) {
            string key = CreateMasterCacheKey(); 
            Cache.SaveDataToCache(key, totalRowCount);
        }

 
        /// 
        /// Saves view state. 
        ///  
        protected override object SaveViewState() {
            Pair myState = new Pair(); 

            myState.First = base.SaveViewState();

            if (_view != null) { 
                myState.Second = ((IStateManager)_view).SaveViewState();
            } 
 
            if ((myState.First == null) &&
                (myState.Second == null)) { 
                return null;
            }

            return myState; 
        }
 
        ///  
        /// Returns all the rows of the datasource.
        /// Parameters are taken from the SelectParameters property collection. 
        /// 
        public IEnumerable Select() {
            return GetView().Select(DataSourceSelectArguments.Empty);
        } 

 
        ///  
        /// Starts tracking view state.
        ///  
        protected override void TrackViewState() {
            base.TrackViewState();

            if (_view != null) { 
                ((IStateManager)_view).TrackViewState();
            } 
        } 

 
        /// 
        /// Updates rows in the data source indicated by the parameters in the UpdateParameters collection.
        /// 
        public int Update() { 
            return GetView().Update(null, null, null);
        } 
    } 
}
                        

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