Validation With Drop Down List

Question

How can i use validation with Drop down List?

Satyapriya Nayak · Answer

Hi Swati Suppose in your application you are using a DropDownList in a Form and depending upon the item selection you are showing/hiding some views inside a Multiview and you want that the user must select one of the item from the DropDownList before submitting a Form. So you can write code like the following to validate the DropDown : asp : DropDownList ID =ddlExpertLevel runat =server AutoPostBack =True onselectedindexchanged =ddlExpertLevel_SelectedIndexChanged > asp : ListItem Text =--Select-- Value =0 /> asp : ListItem Text =Beginner Value =1 /> asp : ListItem Text =Intermediate Value =2 /> asp : ListItem Text =Advanced Value =3 /> asp : DropDownList > asp : RequiredFieldValidator ID =reqValQuestionType runat =server ErrorMessage =Level is required. Text =* ControlToValidate =ddlExpertLevel InitialValue =0> asp : RequiredFieldValidator > This code will work fine but it has an issue. The issue is - If page validation returns false and after that you are trying to change the DropDown's index then it will not work for first time. Because when you submit the form it will do Form validation. If Validation returns false [indicates not to submit the Form] then you can can't go to server side code. The problem lies here. Since you have used SelectedstateChanged event for the Dropdown the code inside the event handler function will not execute after form validation[when validation will return false]. So How to handle this problem. The solution is very simple you have to do the following things - Make CausesValidation =false for the DropDown. Remove any validation group for that DropDown i.e ValidationGroup =none Handle client side change event to avoid Blocking of Submit on DropDown item change i.e onchange =Page_BlockSubmit = false; So the final code would look like : asp : DropDownList ID =ddlExpertLevel runat =server AutoPostBack =True CausesValidation =false ValidationGroup =none onchange =Page_BlockSubmit = false; onselectedindexchanged =ddlExpertLevel_SelectedIndexChanged > asp : ListItem Text =--Select-- Value =0 /> asp : ListItem Text =Beginner Value =1 /> asp : ListItem Text =Intermediate Value =2 /> asp : ListItem Text =Advanced Value =3 /> asp : DropDownList > asp : RequiredFieldValidator ID =reqValQuestionType runat =server ErrorMessage =Level is required. Text =* ControlToValidate =ddlExpertLevel InitialValue =0> asp : RequiredFieldValidator > Please refer the below link http://www.mindfiresolutions.com/DropDownList-Validation-problem-in-ASPNET-736.php Thanks If this post helps you mark it as answer

Swati Agarwal · Answer

thankx Satyapriya...

Swati Agarwal · Answer

Dropdownlist_Selectionchangedevent

Sachin Kalia · Answer

Swati These are few links which would help you out to enable validation on dropdownlist using server side as well as client side. http://asp-net-example.blogspot.in/2008/10/dropdownlist-example-how-to-validate.html http://www.mindfiresolutions.com/DropDownList-Validation-problem-in-ASPNET-736.php http://www.codeproject.com/Tips/404274/Client-Side-Validation-using-JavaScript Happy Coding !

Dorababu Meka · Answer

Bind the dropddownlist as follows

Santhosh Kumar Jayaraman · Answer

What kind of validation? Mostly you need to to validation in Dropdownlist_Selectionchangedevent