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//------------------------------------------------------------------------------
// <copyright file="DataBoundControl.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.UI.WebControls {
using System;
using System.Collections;
using System.ComponentModel;
using System.Web.Util;
using System.Web.UI.WebControls.Adapters;
/// <summary>
/// A DataBoundControl is bound to a data source and generates its
/// user interface (or child control hierarchy typically), by enumerating
/// the items in the data source it is bound to.
/// DataBoundControl is an abstract base class that defines the common
/// characteristics of all controls that use a list as a data source, such as
/// DataGrid, DataBoundTable, ListBox etc. It encapsulates the logic
/// of how a data-bound control binds to collections or DataControl instances.
/// </summary>
[
Designer("System.Web.UI.Design.WebControls.DataBoundControlDesigner, " + AssemblyRef.SystemDesign),
]
public abstract class DataBoundControl : BaseDataBoundControl {
private DataSourceView _currentView;
private bool _currentViewIsFromDataSourceID;
private bool _currentViewValid;
private IDataSource _currentDataSource;
private bool _currentDataSourceValid;
private DataSourceSelectArguments _arguments;
private bool _pagePreLoadFired;
private bool _ignoreDataSourceViewChanged;
private string _itemType;
private string _selectMethod;
private ModelDataSource _modelDataSource;
private const string DataBoundViewStateKey = "_!DataBound";
private static readonly object EventCreatingModelDataSource = new object();
private static readonly object EventCallingDataMethods = new object();
/// <summary>
/// The name of the list that the DataBoundControl should bind to when
/// its data source contains more than one list of data items.
/// </summary>
[
DefaultValue(""),
Themeable(false),
WebCategory("Data"),
WebSysDescription(SR.DataBoundControl_DataMember)
]
public virtual string DataMember {
get {
object o = ViewState["DataMember"];
if (o != null) {
return (string)o;
}
return String.Empty;
}
set {
ViewState["DataMember"] = value;
OnDataPropertyChanged();
}
}
protected override bool IsUsingModelBinders {
get {
return !String.IsNullOrEmpty(SelectMethod);
}
}
private ModelDataSource ModelDataSource {
get {
if (_modelDataSource == null) {
_modelDataSource = new ModelDataSource(this);
}
return _modelDataSource;
}
set {
if (value == null) {
throw new ArgumentNullException("value");
}
_modelDataSource = value;
}
}
[
WebCategory("Data"),
WebSysDescription(SR.DataBoundControl_OnCreatingModelDataSource)
]
public event CreatingModelDataSourceEventHandler CreatingModelDataSource {
add {
Events.AddHandler(EventCreatingModelDataSource, value);
}
remove {
Events.RemoveHandler(EventCreatingModelDataSource, value);
}
}
protected virtual void OnCreatingModelDataSource(CreatingModelDataSourceEventArgs e) {
CreatingModelDataSourceEventHandler handler = Events[EventCreatingModelDataSource] as CreatingModelDataSourceEventHandler;
if (handler != null) {
handler(this, e);
}
}
/// <summary>
/// The name of the model type used in the SelectMethod, InsertMethod, UpdateMethod, and DeleteMethod.
/// </summary>
[
DefaultValue(""),
Themeable(false),
WebCategory("Data"),
WebSysDescription(SR.DataBoundControl_ItemType)
]
public virtual string ItemType {
get {
return _itemType ?? String.Empty;
}
set {
if (!String.Equals(_itemType, value, StringComparison.OrdinalIgnoreCase)) {
_itemType = value;
OnDataPropertyChanged();
}
}
}
/// <summary>
/// The name of the method on the page which is called when this Control does a select operation.
/// </summary>
[
DefaultValue(""),
Themeable(false),
WebCategory("Data"),
WebSysDescription(SR.DataBoundControl_SelectMethod)
]
public virtual string SelectMethod {
get {
return _selectMethod ?? String.Empty;
}
set {
if (!String.Equals(_selectMethod, value, StringComparison.OrdinalIgnoreCase)) {
_selectMethod = value;
OnDataPropertyChanged();
}
}
}
/// <summary>
/// Occurs before model methods are invoked for data operations.
/// Handle this event if the model methods are defined on a custom type other than the code behind file.
/// </summary>
[
WebCategory("Data"),
WebSysDescription(SR.DataBoundControl_CallingDataMethods)
]
public event CallingDataMethodsEventHandler CallingDataMethods {
add {
Events.AddHandler(EventCallingDataMethods, value);
}
remove {
Events.RemoveHandler(EventCallingDataMethods, value);
if (_modelDataSource != null) {
_modelDataSource.CallingDataMethods -= value;
}
}
}
/// <internalonly />
[
IDReferenceProperty(typeof(DataSourceControl))
]
public override string DataSourceID {
get {
return base.DataSourceID;
}
set {
base.DataSourceID = value;
}
}
[
Browsable(false),
DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)
]
public IDataSource DataSourceObject {
get {
return GetDataSource();
}
}
protected DataSourceSelectArguments SelectArguments {
get {
if (_arguments == null) {
_arguments = CreateDataSourceSelectArguments();
}
return _arguments;
}
}
internal void EnsureSingleDataSource() {
//Ensure that only one of data binding methods are opted-in.
if (!DesignMode) {
if (IsUsingModelBinders) {
if (DataSourceID.Length != 0 || DataSource != null) {
throw new InvalidOperationException(SR.GetString(SR.DataControl_ItemType_MultipleDataSources, ID));
}
}
else if (DataSourceID.Length != 0 && DataSource != null) {
throw new InvalidOperationException(SR.GetString(SR.DataControl_MultipleDataSources, ID));
}
}
}
/// <devdoc>
/// Connects this data bound control to the appropriate DataSourceView
/// and hooks up the appropriate event listener for the
/// DataSourceViewChanged event. The return value is the new view (if
/// any) that was connected to. An exception is thrown if there is
/// a problem finding the requested view or data source.
/// </devdoc>
private DataSourceView ConnectToDataSourceView() {
if (_currentViewValid && !DesignMode) {
// If the current view is correct, there is no need to reconnect
return _currentView;
}
// Disconnect from old view, if necessary
if ((_currentView != null) && (_currentViewIsFromDataSourceID)) {
// We only care about this event if we are bound through the DataSourceID property
_currentView.DataSourceViewChanged -= new EventHandler(OnDataSourceViewChanged);
}
EnsureSingleDataSource();
// Connect to new view
_currentDataSource = GetDataSource();
string dataMember = DataMember;
if (_currentDataSource == null) {
// DataSource control was not found, construct a temporary data source to wrap the data
_currentDataSource = new ReadOnlyDataSource(DataSource, dataMember);
}
_currentDataSourceValid = true;
// IDataSource was found, extract the appropriate view and return it
DataSourceView newView = _currentDataSource.GetView(dataMember);
if (newView == null) {
throw new InvalidOperationException(SR.GetString(SR.DataControl_ViewNotFound, ID));
}
_currentViewIsFromDataSourceID = IsDataBindingAutomatic;
_currentView = newView;
if ((_currentView != null) && (_currentViewIsFromDataSourceID)) {
// We only care about this event if we are bound through the DataSourceID property
_currentView.DataSourceViewChanged += new EventHandler(OnDataSourceViewChanged);
}
_currentViewValid = true;
return _currentView;
}
/// <summary>
/// Override to create the DataSourceSelectArguments that will be passed to the view's Select command.
/// </summary>
protected virtual DataSourceSelectArguments CreateDataSourceSelectArguments() {
return DataSourceSelectArguments.Empty;
}
/// <devdoc>
/// Gets the DataSourceView of the IDataSource that this control is
/// bound to, if any.
/// </devdoc>
protected virtual DataSourceView GetData() {
DataSourceView view = ConnectToDataSourceView();
Debug.Assert(_currentViewValid);
return view;
}
/// <devdoc>
/// Gets the IDataSource that this control is bound to, if any.
/// Because this method can be called directly by derived classes, it's virtual so data can be retrieved
/// from data sources that don't live on the page.
/// </devdoc>
protected virtual IDataSource GetDataSource() {
if (!DesignMode && IsUsingModelBinders) {
//Let the developer choose a custom ModelDataSource.
CreatingModelDataSourceEventArgs e = new CreatingModelDataSourceEventArgs();
OnCreatingModelDataSource(e);
if (e.ModelDataSource != null) {
ModelDataSource = e.ModelDataSource;
}
//Update the properties of ModelDataSource so that it's ready for data-binding.
UpdateModelDataSourceProperties(ModelDataSource);
CallingDataMethodsEventHandler handler = Events[EventCallingDataMethods] as CallingDataMethodsEventHandler;
if (handler != null) {
ModelDataSource.CallingDataMethods += handler;
}
return ModelDataSource;
}
if (!DesignMode && _currentDataSourceValid && (_currentDataSource != null)) {
return _currentDataSource;
}
IDataSource 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.DataControl_DataSourceDoesntExist, ID, dataSourceID));
}
ds = control as IDataSource;
if (ds == null) {
throw new HttpException(SR.GetString(SR.DataControl_DataSourceIDMustBeDataControl, ID, dataSourceID));
}
}
return ds;
}
protected void MarkAsDataBound() {
ViewState[DataBoundViewStateKey] = true;
}
protected override void OnDataPropertyChanged() {
_currentViewValid = false;
_currentDataSourceValid = false;
base.OnDataPropertyChanged();
}
/// <devdoc>
/// This method is called when the DataSourceView raises a DataSourceViewChanged event.
/// </devdoc>
protected virtual void OnDataSourceViewChanged(object sender, EventArgs e) {
if (!_ignoreDataSourceViewChanged) {
RequiresDataBinding = true;
}
}
private void OnDataSourceViewSelectCallback(IEnumerable data) {
_ignoreDataSourceViewChanged = false;
// We only call OnDataBinding here if we haven't done it already in PerformSelect().
if (IsDataBindingAutomatic) {
OnDataBinding(EventArgs.Empty);
}
if (AdapterInternal != null) {
DataBoundControlAdapter dataBoundControlAdapter = AdapterInternal as DataBoundControlAdapter;
if(dataBoundControlAdapter != null) {
dataBoundControlAdapter.PerformDataBinding(data);
}
else {
PerformDataBinding(data);
}
}
else {
PerformDataBinding(data);
}
OnDataBound(EventArgs.Empty);
}
protected internal override void OnLoad(EventArgs e) {
ConfirmInitState();
ConnectToDataSourceView();
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(IEnumerable data) {
}
/// <summary>
/// Issues an asynchronous request for data to the data source using the arguments from CreateDataSourceSelectArguments.
/// </summary>
protected override void PerformSelect() {
// We need to call OnDataBinding here if we're potentially bound to a DataSource (instead of a DataSourceID)
// because the databinding statement that is the datasource needs to be evaluated before the call to GetData()
// happens, because we don't rebind when the datasource is changed unless DataSourceID.Length > 0.
if (!IsDataBindingAutomatic) {
OnDataBinding(EventArgs.Empty);
}
DataSourceView view = GetData();
_arguments = CreateDataSourceSelectArguments();
_ignoreDataSourceViewChanged = true;
RequiresDataBinding = false;
MarkAsDataBound();
view.Select(_arguments, OnDataSourceViewSelectCallback);
}
protected override void ValidateDataSource(object dataSource) {
if ((dataSource == null) ||
(dataSource is IListSource) ||
(dataSource is IEnumerable) ||
(dataSource is IDataSource)) {
return;
}
throw new InvalidOperationException(SR.GetString(SR.DataBoundControl_InvalidDataSourceType));
}
/// <devdoc>
/// Loads view state.
/// </devdoc>
protected override void LoadViewState(object savedState) {
if (IsUsingModelBinders) {
Pair myState = (Pair)savedState;
if (savedState == null) {
base.LoadViewState(null);
}
else {
base.LoadViewState(myState.First);
if (myState.Second != null) {
((IStateManager)ModelDataSource).LoadViewState(myState.Second);
}
}
}
else {
base.LoadViewState(savedState);
}
}
/// <devdoc>
/// Saves view state.
/// </devdoc>
protected override object SaveViewState() {
// Bug 322689: In the web farms scenario, if a web site is hosted in 4.0 and 4.5 servers
// (though this is not a really supported scenario, we are fixing this instance),
// the View state created by 4.0 should be able to be understood by 4.5 controls.
// So, we create a Pair only if we are using model binding and otherwise fallback to 4.0 behavior.
object baseViewState = base.SaveViewState();
if (IsUsingModelBinders) {
Pair myState = new Pair();
myState.First = baseViewState;
myState.Second = ((IStateManager)ModelDataSource).SaveViewState();
if ((myState.First == null) &&
(myState.Second == null)) {
return null;
}
return myState;
}
else {
return baseViewState;
}
}
/// <devdoc>
/// Starts tracking view state.
/// </devdoc>
protected override void TrackViewState() {
base.TrackViewState();
if (IsUsingModelBinders) {
((IStateManager)ModelDataSource).TrackViewState();
}
}
/// <summary>
/// Updates the necessary properties on provided ModelDataSource with control's properties.
/// This step must be done before the data source can do data-binding using data operations.
/// </summary>
/// <param name="modelDataSource"></param>
internal virtual void UpdateModelDataSourceProperties(ModelDataSource modelDataSource) {
Debug.Assert(modelDataSource != null, "A non-null ModelDataSource should be passed in");
modelDataSource.UpdateProperties(ItemType, SelectMethod);
}
}
}
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