loadviewstate - Developer IT

LoadViewState not fired on my user control

- by Jeremy

I have a user control nested in a repeater. Inside my user control I have another repeater and in that I have a panel. I am trying to override the LoadViewState event of my user control and dynamically add controls to the panel. I want to do it in the LoadViewState so that the dynamic controls get added before the viewstate gets loaded, so they retain their values after post backs. For some reason the LoadViewState event on the user control (ascx) is not firing. Is there some way to force it to fire, or is there another method I could use? I have ruled out the user controls repeater databind event, because I need it to work even if data binding isn't happening and I can't do it on the repeaters item created event either because the child panel and inner html doesn't exist yet.

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How to set state of controls from viewstate on non PostBack page

- by n1zero

I am currently saving viewstate of pages in cache. I can see that viewstate is rebinding values and controls on PostBack. It is working properly on postback. However, I need to recreate state on a non-post back page.The key i'm using for loading viewstate from cache is being passed in the querystring but I am unable to find a way to force viewstate to load on a non-post back page. Is there any way to force a load of viewstate on a Non-Postbacked Page?

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ASP.NET ViewState Tips and Tricks #2

- by João Angelo

If you need to store complex types in ViewState DO implement IStateManager to control view state persistence and reduce its size. By default a serializable object will be fully stored in view state using BinaryFormatter. A quick comparison for a complex type with two integers and one string property produces the following results measured using ASP.NET tracing: BinaryFormatter: 328 bytes in view state IStateManager: 28 bytes in view state BinaryFormatter sample code: // DO NOT [Serializable] public class Info { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get { object o = this.ViewState["Example_User"]; if (o == null) return null; return (Info)o; } set { this.ViewState["Example_User"] = value; } } } IStateManager sample code: // DO public class Info : IStateManager { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } private bool isTrackingViewState; bool IStateManager.IsTrackingViewState { get { return this.isTrackingViewState; } } void IStateManager.LoadViewState(object state) { var triplet = (Triplet)state; this.Id = (int)triplet.First; this.Name = (string)triplet.Second; this.Age = (int)triplet.Third; } object IStateManager.SaveViewState() { return new Triplet(this.Id, this.Name, this.Age); } void IStateManager.TrackViewState() { this.isTrackingViewState = true; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get; set; } protected override object SaveViewState() { return new Pair( ((IStateManager)this.User).SaveViewState(), base.SaveViewState()); } protected override void LoadViewState(object savedState) { if (savedState != null) { var pair = (Pair)savedState; this.User = new Info(); ((IStateManager)this.User).LoadViewState(pair.First); base.LoadViewState(pair.Second); } } }

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HiddenField.Value is an empty string upon postback inside my custom control

- by Matthew Cox

I have a custom control that has a hidden field. Upon postback I want to obtain the value stored in it, but it's always an empty string. any thoughts? I am performing client-side manipulation of the hidden field values and have verified in firebug that the fields are correct before issue a post back Here is the setup: public class DualListPanel : SWebControl, INamingContainer { protected IList<DlpItem> UnassignedList { get; set; } protected IList<DlpItem> AssignedList { get; set; } private HiddenField assignedItemsField, unassignedItemsField; public DualListPanel() { CssClass = "DualListPanel"; EnableViewState = true; } #region ViewState protected override void LoadViewState(object savedState) { var state = savedState as object[]; UnassignedList = state[0] as List<DlpItem>; AssignedList = state[1] as List<DlpItem>; base.LoadViewState(state[2]); } protected override object SaveViewState() { object[] state = new object[3]; state[0] = UnassignedList; state[1] = AssignedList; state[2] = base.SaveViewState(); return state; } #endregion #region WebControl Overrides protected override void CreateChildControls() { assignedItemsField = new HiddenField(); assignedItemsField.ID = "HiddenAssignedItems"; assignedItemsField.EnableViewState = true; unassignedItemsField = new HiddenField(); unassignedItemsField.ID = "HiddenUnassignedItems"; unassignedItemsField.EnableViewState = true; Controls.Add(assignedItemsField); Controls.Add(unassignedItemsField); base.CreateChildControls(); } #endregion #region Item Lists Retrieval public string GetCommaDelimUnassignedItems() { return unassignedItemsField.Value; } public string GetCommaDelimAssignedItems() { return assignedItemsField.Value; } #endregion }

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Asp.NET ReportViewer “report execution has expired or cannot be found” error when using session state service or SQL Server session state

- by dotneteer

We encountered an error like: ReportServerException: The report execution x5pl2245iwvvq055khsxzlj5 has expired or cannot be found. (rsExecutionNotFound)] Microsoft.Reporting.WebForms.ServerReportSoapProxy.OnSoapException(SoapException e) +72 Microsoft.Reporting.WebForms.Internal.Soap.ReportingServices2005.Execution.ProxyMethodInvocation.Execute(RSExecutionConnection connection, ProxyMethod`1 initialMethod, ProxyMethod`1 retryMethod) +428 Microsoft.Reporting.WebForms.Internal.Soap.ReportingServices2005.Execution.RSExecutionConnection.GetExecutionInfo() +133 Microsoft.Reporting.WebForms.ServerReport.EnsureExecutionSession() +197 Microsoft.Reporting.WebForms.ServerReport.LoadViewState(Object viewStateObj) +256 Microsoft.Reporting.WebForms.ServerReport..ctor(SerializationInfo info, StreamingContext context) +355 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeMethodHandle._SerializationInvoke(Object target, SignatureStruct& declaringTypeSig, SerializationInfo info, StreamingContext context) +0 System.Reflection.RuntimeConstructorInfo.SerializationInvoke(Object target, SerializationInfo info, StreamingContext context) +108 System.Runtime.Serialization.ObjectManager.CompleteISerializableObject(Object obj, SerializationInfo info, StreamingContext context) +273 System.Runtime.Serialization.ObjectManager.FixupSpecialObject(ObjectHolder holder) +49 System.Runtime.Serialization.ObjectManager.DoFixups() +223 System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +188 System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +203 System.Web.Util.AltSerialization.ReadValueFromStream(BinaryReader reader) +788 System.Web.SessionState.SessionStateItemCollection.ReadValueFromStreamWithAssert() +55 System.Web.SessionState.SessionStateItemCollection.DeserializeItem(String name, Boolean check) +281 System.Web.SessionState.SessionStateItemCollection.DeserializeItem(Int32 index) +110 System.Web.SessionState.SessionStateItemCollection.get_Item(Int32 index) +17 System.Web.SessionState.HttpSessionStateContainer.get_Item(Int32 index) +13 System.Web.Util.AspCompatApplicationStep.OnPageStartSessionObjects() +71 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2065 This error occurs long after the report viewer page has closed. It occurs to any asp.net page in the application, rendering the entire application unusable until the user gets a new session. The cause of the problem is that the ReportViewer uses session state. When a page retrieves session from any out-of-state session, the session variable of type Microsoft.Reporting.WebForms.ReportHierarchy is deserialized from the session storage. The deserialization could cause the object to connect to the report server when the report is no longer available. The solution is simple but not pretty. We need to clean up the session variable when the report viewer page is closed. One way is to add some Javascript to the page to handle the window.onunload event. In the event handler, call a web service to clean up the session variable. The name of the session variable appears to be randomly generated. So we need to loop through the session variable to find a variable of the type Microsoft.Reporting.WebForms.ReportHierarchy. Microsoft has implemented pinging between the report viewer and the report server to keep the report alive on the server when the report viewer is up; I hope they will go one step further to take care of this problem.

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