Bind and Eval perform approximately the same function, reading data from a data source. Selected Value End Sub Use Bind for the Drop Down List Selected Value and the code in Listing 1 is not needed. Modify the Customer ID by picking a Customer from the Drop Down List and click the Update button provided by the Form View designer.The difference is that Bind is a two-way bind (read and write) and Eval is a one way bind (read-only) from the Data Source. Item Updating Dim control As Drop Down List = Form View1. If you use Eval then remember that the Drop Down List is in a template of the Form View, so you have to get the actual Drop Down List by calling Find Control and setting the updated value to the e. The running form is shown in Figure 3, and the ASP.NET view and replace the Customer ID Text Box with a Drop Down List.Next you will need to configure the data source for the Drop Down List and bind the Drop Down List to the source for the list items and the source for the selected value.Protected Sub Form View1_Item Updating(By Val sender As Object, _ By Val e As System. The key to binding is the second Data Source for the lookup and understanding the difference between Bind and Eval.Bind reads and writes and Eval only reads from the Data Source.Data source components offer an alternative to the classic ASP.NET binding model based on a programmatic and explicit binding between enumerable data and the Data Source property of data-bound controls. NET 2.0, all data-bound controls support data source components for fetching, but only a few of them are designed to use data source components for other operations such as insertion, deletion, and update.
The next step is to change out a Text Box for a Drop Down List in the Edit Item Template and get data into the Drop Down List.
The Data Value Field and Data Text Field's are assigned to Customer ID and Company Name respectively, and lookup values will come from the Customers table.
The Eval method in the script block implies that the Selected Value is read from the outer data source's Customer ID field.
To demonstrate data binding for a Drop Down List in a Form View switch the Form View to the Edit Item Template.
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