With the exception of list-based container controls like a DataGrid , GridView , or Repeater , during the DataBinding event would be where any dynamic child controls are created and their data sources assigned. Above, we bind our TextBox control to the name of our company.
TextBox does not have a DataSource property, so the company name is manually assigned directly to the control's Text property. Note: RowCreated is used for the GridView control, only. This event will execute once for each item in the DataSource collection, and correspond to one Row or Item in the control. On execution, the individual Row or Item in your control has been created, any child controls specified in your markup have been initialized and loaded, and the individual data item is available for manipulation.
However, data binding has not yet been executed on the row or any of its child controls. This event cannot be dependent upon any control data since the binding has yet to occur. An example scenario that would use this event would be if your data item contained another list, such as our Department class instance that contains a list of Employees, and the Employees will display in a dropdown. During the created event, the dropdown's DataSource can be assigned to the list contained within the Employees property.
NET will automatically execute the DataBind method on the Employees dropdown, binding the list data to populate the control. This automatic execution of DataBind applies to all child controls of the Row or Item, including controls defined in the Code-In-Front markup or those that were manually created in the code-behind.
Be aware that any code in the Created events cannot be dependent upon Control data. Items list property is still empty. Executing code dependant upon control data, such as setting the selected item, will fail. The ItemCreated event creates a label for the name of the department, assigning the name, and a DropDownList of Employees, assigning only the list's DataSource. ItemCreated is repeated for every item in the repeater's DataSource collection, or in other words, every department associated with our company.
Because DataBinding has not yet executed for any child control, none of the Employee list items exist in our dropdown, but because it has not yet executed, we also do not need to manually create the ListItems or manually re-execute DropDownList. This event fires when the data binding process has completed for all child controls within the Row or Item.
All controls within the row have their data, and code that is dependant upon control data, such as setting a selected item, can now be executed. It is strongly advised that this event contains no modifications to the item data that would require a DataBind method to be executed; this sort of data manipulation should occur instead in the Created events, prior to Data Binding the child control tree. If DataBind were to be executed again on this control, the Data Binding process for this control and all children is restarted and re-executed, causing controls to be Data Bound two or more times and potentially leading to an unknown state and adverse outcomes in your application.
The DataBound events indicate that binding has been completed for this item and all child controls; for us, this means our DropDownList of employees has been fully bound, and that a ListItem exists for each Employee.
We can use this post-binding event to perform any data-dependent logic. As with ItemCreated , this event will execute for each item in our repeater's DataSource collection. NET Web Forms: one method and three events. When done properly, the DataBind method should only be called once on a control tree. Execute DataBind directly on the page, or execute it once on individual controls such as each of your top-level Repeaters, but whatever path you follow, make sure that the method is not executed twice on any single control.
Use the binding events to make this happen. Failure to do so can cause unfortunate side effects and extensive pain. Raised after the control's DataBinding event. Use this event to manipulate content that is not dependent on data binding. For example, at run time, you might programmatically add formatting to a header or footer row in a GridView control. Raised after the control's RowCreated or ItemCreated event. When this event occurs, data is available in the row or item, so you can format data or set the FilterExpression property on child data source controls in order to display related data within the row or item.
Raised at the end of data-binding operations in a data-bound control. In a GridView control, data binding is complete for all rows and any child controls. Use this event to format data-bound content or to initiate data binding in other controls that depend on values from the current control's content. If a child control has been data bound, but its container control has not yet been data bound, the data in the child control and the data in its container control can be out of sync.
This is true particularly if the data in the child control performs processing based on a data-bound value in the container control. For example, suppose you have a GridView control that displays a company record in each row, and it displays a list of the company officers in a ListBox control. To fill the list of officers, you would bind the ListBox control to a data source control such as SqlDataSource that retrieves the company officer data using the company ID in a query.
In this case, the child control the ListBox control is bound before the containing control the GridView control is bound, so their data-binding stages are out of sync. To avoid this condition, put the data source control for the ListBox control in the same template item as the ListBox control itself, and do not set the data binding properties of the ListBox declaratively. Instead, set them programmatically at run time during the RowDataBound event, so that the ListBox control does not bind to its data until the CompanyID information is available.
The Login control can use settings in the Web. However, if your application requires you to customize how the control works, or if you want to understand how Login control events relate to the page life cycle, you can use the events listed in the following table.
Raised during a postback, after the page's LoadComplete event has occurred. This event marks the beginning of the login process. Raised after the LoggingIn event. Use this event to override or enhance the default authentication behavior of a Login control. Use this event to redirect to another page or to dynamically set the text in the control.
This event does not occur if there is an error or if authentication fails. Use this event to set text in the control that explains the problem or to direct the user to a different page. NET Web Applications. NET Web Pages. Developing Custom ASP.
NET Page Syntax. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Stage Description Page request The page request occurs before the page life cycle begins.
Start In the start stage, page properties such as Request and Response are set. Initialization During page initialization, controls on the page are available and each control's UniqueID property is set. Load During load, if the current request is a postback, control properties are loaded with information recovered from view state and control state.
Postback event handling If the request is a postback, control event handlers are called. Rendering Before rendering, view state is saved for the page and all controls. Unload The Unload event is raised after the page has been fully rendered, sent to the client, and is ready to be discarded. Life-Cycle Events Within each stage of the life cycle of a page, the page raises events that you can handle to run your own code.
Use this event for the following: Check the IsPostBack property to determine whether this is the first time the page is being processed. Create or re-create dynamic controls.
Set a master page dynamically. Read or set profile property values. Note If the request is a postback, the values of the controls have not yet been restored from view state. Note In a postback request, if the page contains validator controls, check the IsValid property of the Page and of individual validation controls before performing any processing. Note During the unload stage, the page and its controls have been rendered, so you cannot make further changes to the response stream.
In this article. Raised after the start stage is complete and before the initialization stage begins. Use this event to read or initialize control properties. Raised at the end of the event-handling stage. Use this event for tasks that require that all other controls on the page be loaded. Raised for each control and then for the page. To fill the list of officers, you would bind the ListBox control to a data source control such as SqlDataSource that retrieves the company officer data using the CompanyID in a query.
In this case, the child control the ListBox control is bound before the containing control the GridView control is bound, so their data-binding stages are out of sync. To avoid this condition, put the data source control for the ListBox control in the same template item as the ListBox control itself, and do not set the data binding properties of the ListBox declaratively. Instead, set them programmatically at run time during the RowDataBound event, so that the ListBox control does not bind to its data until the CompanyID information is available.
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