Updating objectdatasource

28-Dec-2016 00:11 by 10 Comments

Updating objectdatasource

NET Web Forms is similar to data binding in Win Forms.You don’t need to explicitly trigger data binding events; you just need to make sure any bindable element is connected to the correct data source.

To help prevent this, in this tutorial, we'll add a client-side confirmation dialog box that appears when the Delete button is clicked.

Scott Mitchell April 2007 Summary: This is the Visual C# tutorial.

(Switch to the Visual Basic tutorial.) In the interfaces we've created so far, a user can accidentally delete data by clicking the Delete button when they meant to click the Edit button.

Most web applications get data from the middle tier and display it in a nice-looking HTML layout. For example, the Label control in Listing 1 will update its Text property only when it receives a Data Binding event. As a developer, you have the power to trigger data binding events for individual controls (including child controls) or for all controls within a page. Subsequently, any controls with a data binding expression will update themselves.

This common pattern brought framework authors to introduce a semi-automatic mechanism to facilitate the display of data into well-defined UI components. Data binding is the process that retrieves data from a given data source and associates it to attributes of UI elements. I’ll start with simple forms of data binding, then discuss the various types of data source controls and data bound controls. NET data binding is the association between the property of a server control and a server-side calculated value. This code is supposed to use a Label control to display the city that a user selects from a drop-down list. Web Figure 1 shows the results from calling the Data Bind method on the page created with the code in Listing 1 (below).

The data source can be virtually any software component that exposes data, including in-memory elements (e.g., arrays, collections), properties of live objects, and stream-based data flows (e.g., result sets from database queries). This association is established at compile time and buried in the folds of the code that ASP. Web Figure 1: Data binding in action If you don’t want to call Data Bind on each page in which you intend to use data binding, you can craft a new page class that overrides the On Load method. This code creates the Data Binding Page class, which loads the Data Bind method instead of the On Load method when the Load event is triggered.

Then, all you need to do is derive each page from the Data Binding Page class by using the following code: Done this way, data binding in ASP.The Delete() method then invokes the configured method from the Business Logic Layer, which propagates the call down to the Data Access Layer, issuing the actual DELETE statement to the database.While this user interface enables visitors to delete records through the Grid View, Details View, or Form View control, it lacks any sort of confirmation when the user clicks the Delete button.Raise your hand if you’ve written a web application that couldn’t be cataloged as a data-driven application. To data-bind all the controls in a page, you need code like that in Listing 2 (below).I’m betting that you didn’t raise your hand, because the definition of a data-driven application is quite blurred and flexible enough to incorporate nearly everything. NET controls, behaviors are attached to the control’s life cycle through the Data Binding event handler. It’s the page—if you properly instruct it to do so. Calling the Data Bind method has the effect of triggering the Data Binding event for all the controls in scope. looked at Reset Bindings(), but it has not produced the correct result. Reset Bindings(false) and re-assigning the datsource caused flickering with potentiail overhead if only one item change frequently. Documentation for End Edit seems to indicate that it would do nothing if the objects contained by the datasource do not implement ' IEditable Object'.

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