how to validate dropdownlist in asp.net using vb.net

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i have some fields on the page along with button and couple of textbox dropdown list , drop down list are auto post= true because there are getting data from database on page load and selected index change i wants to validate while button press to save , i don't wants to save null values to DB i tried requiredfield validater to validate but autopost back not working

kindly help me on that

Regards

Yogesh

Posted 4-May-14 23:41pm

yogeshrrc

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DamithSL 5-May-14 5:46am

update the question with related code, how you binding your drop down list? what is the initial value? can you show the aspx code of your RequiredFieldValidator and DropDownList ?

yogeshrrc 7-May-14 6:56am

<table width="100%" border="0">
<tr>
<td colspan="5" align="center" height="15">
</td>
</tr>
<tr>
<td colspan="5" align="center">
</td>
</tr>
<tr>
<td width="10" height="15">
</td>
<td height="38" align="left">
Name:
</td>
<td align="left" style="width: 212px">
<asp:TextBox ID="txtname" runat="server" Height="15px" Width="150px"
ValidationGroup="postreqvalidate"><br />
<asp:requiredfieldvalidator runat="server"
errormessage="Name is Required" ID="chknm" ControlToValidate="txtname"
ValidationGroup="postreqvalidate">
</td>
<td height="33" align="left">
Email:
</td>
<td align="left">
<asp:TextBox ID="txtemail" runat="server" Height="15px" Width="150px"
TabIndex="1" ValidationGroup="postreqvalidate"><br />
<asp:requiredfieldvalidator runat="server" errormessage="Email is Required"
ControlToValidate="txtemail" ValidationGroup="postreqvalidate">
<asp:regularexpressionvalidator runat="server"
errormessage="Enter Correct Email id" ControlToValidate="txtemail"
ValidationGroup="postreqvalidate">
</td>
</tr>
<tr>
<td width="10" height="15">
</td>
<td height="45" align="left">
Telephone:
</td>
<td align="left" style="width: 212px">
<asp:TextBox ID="txtcontact" runat="server" Height="15px" Width="150px"
TabIndex="2" ValidationGroup="postreqvalidate">
<br />
<asp:requiredfieldvalidator runat="server" errormessage="Contact is Required"
ControlToValidate="txtcontact" ValidationGroup="postreqvalidate">
</td>
<td height="38" align="left">
Looking For :
</td>
<td align="left">
<asp:DropDownList ID="DDLlooking" runat="server" Width="150px" TabIndex="3"
ValidationGroup="postreqvalidate">
<asp:ListItem>Select
<asp:ListItem>Buy
<asp:ListItem>Lease

<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
ControlToValidate="DDLlooking"
ErrorMessage="Please Select What are You Looking For ?" InitialValue="Select"
ValidationGroup="postreqvalidate">
<br />
</td>
</tr>
<tr>
<td width="10" height="15">
</td>
<td height="38" align="left">
Property Type :
</td>
<td align="left" style="width: 212px">
<asp:DropDownList ID="DDLPType" runat="server" Width="150px" TabIndex="4"
AutoPostBack="True" ValidationGroup="postreqvalidate">
<asp:ListItem>Select

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KaushalJB · Answer 1 · 2014-05-05T20:57:00

Do provide ValidationGroup to your dropdown and also to your RequiredField Validator

You can go through this code for javascript validation :

function manageValidation()
{

Validate the Page:
// validate all the validation that are present in the page.

Page_ClientValidate();

Validate the Page having certain validation Group:
// validate all the validation that are present in the page with this validation group.

Page_ClientValidate('ValidationGroup');

Get Is the page valid:
// Check wheather the page is valid or not

var pageValidated = Page_IsValid;
 if (pageValidated)
{
// Write some custom messages like

alert('Thanks for signing up with us. we will send your password to respective mail account');

}
else
{

// Other messages..

}

Enable or disable any validation :

// disable a certion validation
// ValidatorEnable(Control Name, status)

ValidatorEnable('requiredvalidatorTxtLastName', false)

// Enable some validation.

ValidatorEnable('requiredvalidatorTxtUserName', true)

Force Validation:

// Attach a certion validation with the control

ValidatorHookupControl('txtUserName', 'requiredvalidatorTxtUserName')

// Validate a certain validation.

ValidatorValidate('requiredvalidatorTxtUserName')

}
 
Manual Validation :
If you want to make the validation false of the page for any customize javascript Code you can do it as follows.

function checkPoints(sender,args)
{
  if(document.getElementById('txtPoints').value == (parseInt(    document.getElementById('txtBasicPoint').value) * 2)
   {
     args.isValid = false;
    }
}