Figure 16 shows this page when viewed through a browser at this point. If not, it returns false, indicating that the request to update the product information failed. Since we want to use this DetailsView to add new products, we need to check the Enable Inserting option from the smart tag; however, there's no such option because the ObjectDataSource's Insert method is not mapped to a method in the ProductsBLL class recall that we set this mapping to None when configuring the data source see Figure 3. This Label control will be displayed if the user fails to specify a UnitPrice value when updating a product. What we want, however, is an inserting interface that provides a means for the user to quickly add a new product to the database. Take a moment to set this property to true. When the user enters a product name and price such as "Acme Water" and 1. The next screen lists the mappings from the ObjectDataSource's methods to the underlying object's.
Hence, the ObjectDataSource wizard selects these each time you run the wizard unless there's some other value explicitly specified. To illustrate working with the parameter values at the ObjectDataSource level, let's include a DetailsView in our page that allows the users to add a new product. Parse , parsing the value as a currency. We can overwrite the existing UnitPrice value in the NewValues collection with a decimal value parsed using the currency format with the following lines of code in the RowUpdating event handler: This can be accomplished by removing the other BoundFields and CheckBoxFields, by setting those other fields' ReadOnly property to true, or by some combination of the two. Furthermore, since the Update method is mapped to the UpdateProduct method overload that only accepts three input parameters, the UpdateParameters section has just three Parameter instances. When the Update method is invoked, the ObjectDataSource's Updating event fires, providing an opportunity to add or customize the values of any of the UpdateParameters. Finally, set the Label's CssClass property to Warning. This DetailsView will be used to provide an interface for quickly adding a new product to the database. Figure 1 depicts this series of events and steps when updating a GridView. As discussed in the previous tutorial, it is vitally important that the GridView s view state be enabled the default behavior. Cancel to true and display a message explaining why if the UnitPrice value in the NewValues collection is null. Figure 16 shows this page when viewed through a browser at this point. What we want, however, is an inserting interface that provides a means for the user to quickly add a new product to the database. Go to the Source view to inspect the ObjectDataSource's declarative markup, which is shown below: Similarly, if there is some combination of non-read-only product fields in the GridView that doesn't correspond to the input parameters for a UpdateProduct overload, an exception will be raised when attempting to update. For this tutorial, let's use the latter option and create an overload of the UpdateProduct method, one that takes in just three input parameters: In order to show the DetailsView in its inserting mode we need to set the DefaultMode property to Inserting. These events fire before the associated method of the underlying object is invoked and provide a last-chance opportunity to modify the input parameters collection or cancel the operation outright. When the user enters a product name and price such as "Acme Water" and 1. The event handlers for these three events are passed an object of type ObjectDataSourceMethodEventArgs that has two properties of interest: With this change, the value of the UnitPrice displayed in the edited row is also formatted as a currency. If there is not a corresponding parameter, the GridView adds one to the collection. Similarly, if a required field, such as ProductName, is removed from the editing interface, the update will fail with a "Column 'ProductName' does not allow nulls" exception. However, since our BLL methods don't expect the original ProductID value to be passed in, remove this property assignment altogether from the ObjectDataSource's declarative syntax. Since this editing interface only provides a subset of a product's fields, we either need to create an ObjectDataSource that uses the existing BLL's UpdateProduct method and has the missing product field values set programmatically in its Updating event handler, or we need to create a new BLL method that expects only the subset of fields defined in the GridView.
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