ASP.NET Validations Tips and Tricks Part-II

Introduction

Validation controls are used to validate the ASP.NET input server controls like asp:TextBox for valid data when their data is submitted to the server.

There are six validation controls in ASP.NET and they are

    1. RequiredFieldValidator
    2. RangeValidator
    3. CompareValidator
    4. RegularExpressionValidator
    5. CustomValidator and
    6. ValidationSummary

I have recently published ASP.NET, ADO.NET, jQuery, HTML, CSS and JavaScript How to Tips and Tricks, click here to get it.

Now lets learn Tips and Tricks related with ASP.NET Validation controls. 

How to validate two different sets of Form fields separately?

In case we have more than one html form on the page and we want to validate them separately or we have two sets of form elements and we want to validate them separately, we can follow this approach.

ASPX PAGE

<fieldset>
<legend><b>User Login</b></legend>
<p>
Username: <asp:TextBox ID="txtUserName" runat="server" 
ValidationGroup="LoginForm1" />
             <asp:RequiredFieldValidator ID="req1" runat="server" ErrorMessage="Mandatory
!" ForeColor="Red" ControlToValidate="txtUserName" ValidationGroup="LoginForm1" />
</p>
<p>
      Password: <asp:TextBox ID="txtPassword" runat="server" TextMode="Password" ValidationGroup="LoginForm1" />
       <asp:RequiredFieldValidator ID="req2" runat="server" ErrorMessage="Mandatory
!" ForeColor="Red" ControlToValidate="txtPassword" ValidationGroup="LoginForm1" />
            </p>
            <asp:Button ID="btnSubmit" runat="server" Text="Login" OnClick="SubmitData1" ValidationGroup="LoginForm1" />
     </fieldset>



<fieldset>
    <legend><b>Admin Login</b></legend>
     <p>
   Username: <asp:TextBox ID="txtAUserName" runat="server" 
ValidationGroup="LoginForm2" />
           <asp:RequiredFieldValidator ID="req3" runat="server" ErrorMessage="Mandatory
!" ForeColor="Red" ControlToValidate="txtAUserName" ValidationGroup="LoginForm2" />
            </p>
           <p>
            Password:<asp:TextBox ID="txtAPassword" runat="server" TextMode="Password" ValidationGroup="LoginForm2" />
            <asp:RequiredFieldValidator ID="req4" runat="server" ErrorMessage="Mandatory
!" ForeColor="Red" ControlToValidate="txtAPassword" ValidationGroup="LoginForm2" />
             </p>
             <asp:Button ID="btnASubmit" runat="server" Text="Login" OnClick="SubmitData2" ValidationGroup="LoginForm2" />
       </fieldset>
 

CODE BEHIND

protected void SubmitData1(object sender, EventArgs e)
{
}

protected void SubmitData2(object sender, EventArgs e)
{
}
 

In the above code snippet, on .aspx page we have two sets of Login form (User Login and Admin Login) separately. To validate both forms separately we can distinguish their controls using ValidationGroup property. Notice that both forms asp.net server controls have “LoginForm1” and “LoginForm2” as ValidationGroup that causes the forms to be validated separately.

OUTPUT

How to validate a textbox for range of values?

In case we want to validate a texbox for the specific range of values, we can follow this approach.

ASPX PAGE

 Enter year between 2000 to 2010: <asp:TextBox ID="txtRange" runat="server" /><br />
        <asp:RangeValidator ID="range1" runat="server" ErrorMessage="Sorry, must be
between 2000 and 2010" ControlToValidate="txtRange" 
        MaximumValue="2010" MinimumValue="2000" Type="Integer" ForeColor="Red" />
<p>
   <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
</p>

In the above code snippet, we have a TextBox that must accept the value in between 2000 and 2010. To validate this range, we can use asp:RangeValidator with MaximumValue as 2010 and MinimumValue as 2000 with Type as “Integer”. This causes the TextBox to accept only values in between 2000 to 2010. 

Notice: The asp:RangeValitor only works if any data is entered to the TextBox, if no data is entered and button is clicked the form get submitted to the server. To avoid this, we should keep asp:RequiredFieldValidator attached with the TextBox to validate.

OUTPUT

Note: Similary Date, Double, String, Currency values can be validated for specific range

How to validate a textbox for correct date?

In case we want to validate a textbox value for the correct date, we can follow this approach.

ASPX PAGE

Date of birth: <asp:TextBox ID="txtDOB" runat="server" /><br />
        <asp:RequiredFieldValidator ID="req1" runat="server" ErrorMessage="Mandatory !" ControlToValidate="txtDOB" ForeColor="Red" />
        <asp:CompareValidator ID="comp1" runat="server" ErrorMessage="Date must be in
MM/DD/YYYY format" 
ControlToValidate="txtDOB" Type="Date" Operator="DataTypeCheck" ForeColor="Red" />
<p>
   <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
</p>
 

In the above code snippet, we have a TextBox that must accept correct date. To do that we can use
asp:CompareValidator with Operator as “DataTypeCheck” and Type as “Date”. We have used
asp:RequiredFieldValidator to force user to enter some data into the TextBox before the form is submitted to the server. When user enter some data and that is not in the correct date format, he/she gets message as displayed in the picture below.

OUTPUT

In case you have missed the 1st article in this series, click here to read.

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