I have a DropDownList
binded with aSqlDataSource
to display the values from the database.
I am unable to validate using a RequiredFieldValidator
.
To use ASP.NET validator with DropDownList control, set the ID of the DropDownList as the value of the ControlToValidate property of the validator. Executing the above code will validate the DropDownList control values on every form submit before post back occurs as given below.
After dragging, our web form looks like the below. Now, to add items to the list, visual studio provides Items property where we can add items. The property window looks like this.
For the most part you treat it as if you are validating any other kind of control but use the InitialValue property of the required field validator.
<asp:RequiredFieldValidator ID="rfv1" runat="server" ControlToValidate="your-dropdownlist" InitialValue="Please select" ErrorMessage="Please select something" />
Basically what it's saying is that validation will succeed if any other value than the 1 set in InitialValue is selected in the dropdownlist.
If databinding you will need to insert the "Please select" value afterwards as follows
this.ddl1.Items.Insert(0, "Please select");
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