In this tutorial, we will cover the basics of
ASP.NET validation techniques. This involves using more advanced
validation controls and ValidationGroups to group validation controls
together.
ValidationGroup Control on Multiple Forms in ASP.NET
In this tutorial, we will cover the basics of
ASP.NET validation techniques. This involves using more advanced
validation controls and ValidationGroups to group validation controls
together.
Form validation is important for the recipient to collect the
correct information and for the user to send the correct information.
It isn't uncommon for a webpage to have multiple forms. Your front page
may have a voting form and email newsletter signup form. Without
validation groups the validations would interfere with each other by
not allowing the user to submit either form unless both forms were
filled out correctly. Validation groups allow the developer to set
groups for each validation control and button.
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First you can start a new Web Application in Visual Studio 2008. We
are going to create a form. This form is going to contain a
DropDownList, RangeValidator, and Button control. You can add all of
these controls through the Toolbox. Below is an example of them.
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Articles: <asp:DropDownList ID="ddArticle" runat="server">
<asp:ListItem Text="Choose an article" Value="-1" Selected="True" />
<asp:ListItem Text="Using Literal Control" Value="1" />
<asp:ListItem Text="Connecting to a SQL Database" Value="2" />
<asp:ListItem Text="Uploading a File to a Database" Value="3" />
<asp:ListItem Text="Creating an AJAX AutoSuggestion Box" Value="4" />
</asp:DropDownList>
<asp:RangeValidator
ValidationGroup="valGroup" ControlToValidate="ddArticle"
ID="reqArticle" MinimumValue="0" MaximumValue="99" runat="server"
ErrorMessage="Please choose an article." /><br />
<asp:Button UseSubmitBehavior="true" ValidationGroup="valGroup"
ID="btnSubmit" Text="Submit" runat="server" /><br /><br
/><br />
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Notice that the RangeValidator and Button control both have the
ValidationGroup attribute set to the same name. This allows the
application only to check the DropDownList's validity when the user
clicks the Submit button.
For tutorial purposes, we will place another form on the same page.
This form will contain a Calendar control, 3 TextBox controls, and 3
validator controls. The first 2 TextBox controls will be for entering
in the user's email address twice. The first TextBox control will
belong to a RequiredFieldValidator and CompareValidator. The
RequireFieldValidator will make sure the user has entered an email
address. The CompareValidator will make sure the user has entered the
same email address twice. The Calendar and TextBox will allow the user
to select a date for the form. A RangeValidator control will be used to
make sure the date is in the month of December 2008.
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Email: <asp:TextBox ID="txtEmail" runat="server" /><br />
Retype Email: <asp:TextBox ID="txtEmail2" runat="server" />
<asp:RequiredFieldValidator
ID="reqEmail" ControlToValidate="txtEmail" ValidationGroup="valGroup2"
runat="server" ErrorMessage="Please enter an email address." />
<asp:CompareValidator
id="compEmail" ValidationGroup="valGroup2" runat="server"
ControlToValidate="txtEmail" ControlToCompare="txtEmail2" Type="String"
Operator="Equal" ErrorMessage="Emails do not match." />
<asp:ScriptManager ID="scrMgr" runat="server" />
<asp:UpdatePanel ID="updPnl" runat="server">
<ContentTemplate>
<asp:Calendar ID="calDate" runat="server" onselectionchanged="calDate_SelectionChanged">
<TodayDayStyle ForeColor="White" BackColor="Black"></TodayDayStyle>
</asp:Calendar><br />
Date: <asp:TextBox ID="txtDate" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
<asp:RangeValidator ValidationGroup="valGroup2" Type="Date"
ControlToValidate="txtDate" ID="reqDate" MinimumValue="12/1/2008"
MaximumValue="12/31/2008" runat="server" ErrorMessage="Date choosen
must be during the month of December of 2008." /><br />
<asp:Button UseSubmitBehavior="true" ID="btnSubmit2" ValidationGroup="valGroup2" Text="Submit" runat="server" />
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Notice the Type attribute for the CompareValidator and
RangeValidator control. If the value being validated is not an integer,
the validation controls will not work properly unless their correct
Type is set. All of the validation controls also have the
ValidationGroup attribute set as valGroup2. This will distinguish the
validation for this form from the validation in the first form.
To make this example complete we will need to program our
application to set the TextBox date to the date selected by the
calendar. You can do this by double-clicking the Calendar control in
design mode. Now set the TextBox to the selectedDate formated to match
our RangeValidator.
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/C#
protected void calDate_SelectionChanged(object sender, EventArgs e)
{
txtDate.Text = calDate.ToShortDateString();
}
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//VB.NET
Protected Sub calDate_SelectionChanged(ByVal sender As Object, ByVal e As EventArgs)
txtDate.Text = calDate.ToShortDateString()
End Sub
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Due to the fact that the validation controls use Javascript, the
page will instantly display an error when a form control isn't valid.
The user will not be allowed to submit the form until all fields for
the current form are valid. We also placed the Calendar control in AJAX
controls so choosing the date will not refresh the entire page. It is
important to note that the error messages can be organized together in
a list by using the ValidationSummary control.
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You have successfully learned how to use a validation control on a
date field and matching email address fields. You have also learned how
to add two different forms to a page with separate validation groups.
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