Skip to main content

RequiredFieldValidator to validate RadioButtonList in asp.net c#

RequiredFieldValidator to validate RadioButtonList
RequiredFieldValidator validation control makes an asp.net web server input control like a mandatory field. Input control validation fails if the value of the control does not change from its initial value. So it will be a required field (input control) for submitting the web form. The user must input some value to pass the validation. You cannot pass validation by only entering space. You can set the RequiredFieldValidator InitialValue property to select another item except for the initial value for passing validation. You can set the ErrorMessage property value to display an error message when validation failed.

This example demonstrates to you how can we validate RadioButtonList control using RequiredFieldValidator. This validation control makes RadioButtonList a mandatory (required) field. So the user must select (check) a list item from RadioButtonList to pass the validation and submit the form. It is very useful when RadioButtonList has no default selection. If the validation fails, the RequiredFieldValidator shows a predefined error message that tells you RadioButtonList is a required field.
RadioButtonListValidation.aspx

<%@ Page Language="C#" %>

<!DOCTYPE html>

<script runat="server">
    protected void Button1_Click(object sender, EventArgs e)
    {
        Label1.Text = "Your favorite: ";
        Label1.Text += RadioButtonList1.SelectedItem.Text.ToString();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>asp.net RequiredFieldValidator example: how to validate RadioButtonList</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:Green">RadioButtonList Validation</h2>
        <asp:Label 
            ID="Label1"
            runat="server"
            Font-Size="Large"
            ForeColor="Crimson"
            >
        </asp:Label>
        <br /><br />
        <asp:Label 
            ID="Label2"
            runat="server"
            Text="Favorite"
            Font-Bold="true"
            ForeColor="DodgerBlue"
            >
        </asp:Label>
        <asp:RadioButtonList 
            ID="RadioButtonList1"
            runat="server"
            RepeatColumns="3"
            BackColor="DodgerBlue"
            ForeColor="AliceBlue"
            BorderColor="DarkBlue"
            BorderWidth="2"
            >
            <asp:ListItem>CheckBoxList</asp:ListItem>
            <asp:ListItem>TreeView</asp:ListItem>
            <asp:ListItem>Button</asp:ListItem>
            <asp:ListItem>SqlDataSource</asp:ListItem>
            <asp:ListItem>GridView</asp:ListItem>
            <asp:ListItem>Calendar</asp:ListItem>
            <asp:ListItem>BulletedList</asp:ListItem>
        </asp:RadioButtonList>
        <asp:RequiredFieldValidator 
            ID="ReqiredFieldValidator1"
            runat="server"
            ControlToValidate="RadioButtonList1"
            ErrorMessage="Select your favorite!"
            >
        </asp:RequiredFieldValidator>
        <br />
        <asp:Button 
            ID="Button1" 
            runat="server" 
            ForeColor="DodgerBlue" 
            Text="Submit Favorite"
            OnClick="Button1_Click"
            />
    </div>
    </form>
</body>
</html>
Labels:

Popular posts from this blog

Restricting Jetpack Compose TextField to Numeric Input Only

Jetpack Compose has revolutionized Android development with its declarative approach, enabling developers to build modern, responsive UIs more efficiently. Among the many components provided by Compose, TextField is a critical building block for user input. However, ensuring that a TextField accepts only numeric input can pose challenges, especially when considering edge cases like empty fields, invalid characters, or localization nuances. In this blog post, we'll explore how to restrict a Jetpack Compose TextField to numeric input only, discussing both basic and advanced implementations. Why Restricting Input Matters Restricting user input to numeric values is a common requirement in apps dealing with forms, payment entries, age verifications, or any data where only numbers are valid. Properly validating input at the UI level enhances user experience, reduces backend validation overhead, and minimizes errors during data processing. Compose provides the flexibility to implement ...
Read more

jetpack compose - TextField remove underline

Compose TextField Remove Underline The TextField is the text input widget of android jetpack compose library. TextField is an equivalent widget of the android view system’s EditText widget. TextField is used to enter and modify text. The following jetpack compose tutorial will demonstrate to us how we can remove (actually hide) the underline from a TextField widget in an android application. We have to apply a simple trick to remove (hide) the underline from the TextField. The TextField constructor’s ‘colors’ argument allows us to set or change colors for TextField’s various components such as text color, cursor color, label color, error color, background color, focused and unfocused indicator color, etc. Jetpack developers can pass a TextFieldDefaults.textFieldColors() function with arguments value for the TextField ‘colors’ argument. There are many arguments for this ‘TextFieldDefaults.textFieldColors()’function such as textColor, disabledTextColor, backgroundColor, cursorC...
Read more

jetpack compose - Image clickable

Compose Image Clickable The Image widget allows android developers to display an image object to the app user interface using the jetpack compose library. Android app developers can show image objects to the Image widget from various sources such as painter resources, vector resources, bitmap, etc. Image is a very essential component of the jetpack compose library. Android app developers can change many properties of an Image widget by its modifiers such as size, shape, etc. We also can specify the Image object scaling algorithm, content description, etc. But how can we set a click event to an Image widget in a jetpack compose application? There is no built-in property/parameter/argument to set up an onClick event directly to the Image widget. This android application development tutorial will demonstrate to us how we can add a click event to the Image widget and make it clickable. Click event of a widget allow app users to execute a task such as showing a toast message by cli...
Read more