How to use RequiredFieldValidator validation control with example in asp.net

Introduction: While creating user input form e.g. registration form  or contact us form etc where user enters the details, we have to implement validations on the form so that empty or incorrect data could not be submitted to server. Asp.net provides Validation controls like CompareValidator, CustomValidator, RangeValidator, RegularExpressionValidator, RequiredFieldValidator etc to apply validations on asp.net web page. In this article I will explain how to use RequiredFieldValidator control to force the user to enter in TextBox i.e. TextBox can't be left blank on submitting to server. 
In previous article i explained How to use CompareValidator validation control with example in asp.net and RegularExpressionValidator  and RangeValidator. and CustomValidator and JavaScript validation in asp.net website and Jquery form validations in asp.net.In this example I have demonstrated 3 ways to use RequiredFieldValidator control. I will post how to user other validation controls in my next articles.

RequiredFieldValidator validation control example in asp.net

Case 1:  If you want to show the validation failure message near to text box for which the validation failed as shown in figure below:

RequiredFieldValidator validation control example in asp.net

then In the design page(.aspx) Place two TextBox controls for entering Name and Address and a Button control for Submitting . Also place two RequiredFieldValidator validation controls from validation category from the visual studio toolbox as shown in figure below:

RequiredFieldValidator validation control example in asp.net

<fieldset style="width:400px;">
            <legend>RequeiredFieldValidator Example in asp.net</legend>
            <table>
                <tr>
                    <td>Name: <span style="color:red;">*</span></td>
                    <td>
                        <asp:TextBox ID="txtName" runat="server"></asp:TextBox>
                    </td>
                     <td>
                         <asp:RequiredFieldValidator ID="rfvName" runat="server" ErrorMessage="Name can't be left blank" ControlToValidate="txtName" ForeColor="#FF3300" SetFocusOnError="True"></asp:RequiredFieldValidator>
                    </td>
                </tr>
                <tr>
                    <td>Address: <span style="color:red;">*</span></td>
                    <td>
                        <asp:TextBox ID="txtAddress" runat="server"></asp:TextBox>
                    </td>
                     <td>
                         <asp:RequiredFieldValidator ID="rfvAddress" runat="server" ErrorMessage="Address can't be left blank" ControlToValidate="txtAddress" ForeColor="#FF3300" SetFocusOnError="True"></asp:RequiredFieldValidator>
                    </td>
                </tr>
                <tr>
                    <td>&nbsp;</td>
                    <td>
                        <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
                    </td>
                </tr>
            </table>
        </fieldset

Case 2: If you want the validation failure message to show in pop up as shown in figure below:

RequiredFieldValidator validation control example in asp.net

then change the Display property of the RequiredFieldValidator validation controls to None and place a ValidationSummary control from the same validation category from the visual studio toolbox. Set the ShowMessageBox property to true and ShowSummary to false as shown below  :
 
<fieldset style="width:400px;">
            <legend>RequeiredFieldValidator Example in asp.net</legend>
            <table>
                <tr>
                    <td>Name: <span style="color:red;">*</span></td>
                    <td>
                        <asp:TextBox ID="txtName" runat="server"></asp:TextBox>
                    </td>
                     <td>
                         <asp:RequiredFieldValidator ID="rfvName" runat="server" ErrorMessage="Name can't be left blank" ControlToValidate="txtName" ForeColor="#FF3300" SetFocusOnError="True" Display="None"></asp:RequiredFieldValidator>
                    </td>
                </tr>
                <tr>
                    <td>Address: <span style="color:red;">*</span></td>
                    <td>
                        <asp:TextBox ID="txtAddress" runat="server"></asp:TextBox>
                    </td>
                     <td>
                         <asp:RequiredFieldValidator ID="rfvAddress" runat="server" ErrorMessage="Address can't be left blank" ControlToValidate="txtAddress" ForeColor="#FF3300" SetFocusOnError="True" Display="None"></asp:RequiredFieldValidator>
                    </td>
                </tr>
                <tr>
                    <td>&nbsp;</td>
                    <td>
                        <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
                    </td>
                </tr>
            </table>

        </fieldset>
        <asp:ValidationSummary ID="ValidationSummary1" runat="server" HeaderText="Please  enter in the following fields" ShowMessageBox="true" ShowSummary="false"  />


Case 3: If you want to show validation failure message in a separate place as shown in figure below :

RequiredFieldValidator validation control example in asp.net

 then Set the ShowMessageBox property to false and ShowSummary property to true.

<asp:ValidationSummary ID="ValidationSummary1" runat="server" ForeColor="#FF3300" HeaderText="Please  enter in the following fields" ShowMessageBox="false" ShowSummary="true" />


Now over to you:

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