Blazor Numeric Textbox Overview

The Blazor Numeric Textbox component allows the user to enter decimal values and no text. The developer can control minimum, maximum values, steps and other elements of the UX.

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Creating Blazor Numeric Textbox

  1. Add the TelerikNumericTextBox tag to your razor page.
  2. Bind a numeric data type to the component
  3. Optionally, set custom Format, Min, Max and Step values

Basic numeric textbox with its key features

The new value is: @theValue

<TelerikNumericTextBox Format="C" Max="5m" Min="-5m" Step="0.33m" @bind-Value="@theValue"></TelerikNumericTextBox>

@code {
     private decimal theValue { get; set; } = 1.234m;
}

The Numeric TextBox component is generic, meaning that it takes the type of its value parameter as an argument. It can take int, long, float, double and decimal values. Therefore, the values for the Min, Max and Step properties must be of the same type as the Value, and the ValueChanged handler must also accommodate the corresponding value type.

Events

The Blazor Numeric TextBox generates events that you can handle and further customize its behavior. Read more about the Blazor Numeric TextBox events....

Validation

You can ensure that the component value is acceptable by using the built-in validation. Read more about input validation....

Custom Format Strings

The Blazor Numeric TextBox allows you to define your desired custom format throu its Format parameter. Here are some examples of using custom format strings.

@Weight
<br />
<TelerikNumericTextBox Format="#.00 kg" Max="5m" Min="-5m" Step="0.33m" @bind-Value="@Weight"></TelerikNumericTextBox>
<br />
@code{
    decimal Weight { get; set; } = 3.456789m;
}

@Rent
<br />
<TelerikNumericTextBox Decimals="2" Format="@RentFormat" @bind-Value="@Rent"></TelerikNumericTextBox>
<br />
@code{
    decimal Rent { get; set; } = 4567.89m;
    string RentFormat { get; set; } = System.Globalization.NumberFormatInfo.CurrentInfo.CurrencySymbol + "#.00 a year";
}

@Units
<br />
<TelerikNumericTextBox Decimals="0" Format="@UnitsFormat" @bind-Value="@Units"></TelerikNumericTextBox>

@code{
    int Units { get; set; } = 12;
    string UnitsFormat { get; set; } = "# unit(s)";
}

Parameters

Attribute Type and Default Value Description
Arrows bool
(true)
Whether to show the up/down spinner arrows (buttons).
DebounceDelay int
150
Time in milliseconds between the last typed symbol and the value update. Use it to balance between client-side performance and number of database queries.
Decimals int Specifies how many decimal places will be allowed while the user is typing a new value. Takes effect only while the input is focused. The default value is set from the specified culture.
Format string The format with which the number is presented when the input is not focused. Read more in the Standard Numeric Format Strings in .NET article.
Id string renders as the id attribute on the <input /> element.
Max Numeric data type the maximum decimal value the input can take. Must be of the same type as the Value.
Min Numeric data type The minimum decimal value the input can take. Must be of the same type as the Value.
Placeholder string maps to the placeholder attribute of the HTML element. The placeholder will appear if the component is bound to nullable value type and there is no value set.
Step Numeric data type the decimal value of the step with which the value changes when the arrows are used. Must be of the same type as the Value.
Value T - expects numeric data type Get/set the value of the input.
TabIndex int? maps to the tabindex attribute of the HTML element. You can use it to customize the order in which the inputs in your form focus with the Tab key.
ValidateOn ValidationEvent enum
ValidationEvent.Input
Configures the event that will trigger validation (if validation is enabled). Read more at Validastion Modes for Simple Inputs.

Styling and Appearance

The following parameters enable you to customize the appearance of the Blazor Numeric TextBox:

Attribute Type and Default Value Description
Class string The CSS class that will be rendered on the topmost wrapping elementof teh component.
Width string the width of the component. See the Dimensions article.

You can find more options for customizing the Numeric TextBox styling in the Appearance article.

Component Reference

@using Telerik.Blazor.Components

<TelerikNumericTextBox @ref="myNumericTextboxRef" @bind-Value="CurrentValue"></TelerikNumericTextBox>

@code {
    //determines the type of the component
    private int CurrentValue { get; set; }

    //the type of the value variable determines the type of the reference
    private Telerik.Blazor.Components.TelerikNumericTextBox<int> myNumericTextboxRef;
}

Notes

  • If you want to use a currency format, you must specify the culture for your app thread, so .NET knows what symbol to render. If you don't do that, you may see an unexpected/incorrect symbol or format. The Telerik Numeric Textbox uses the thread culture for currency signs and decimalr separators (more on globalization in the Telerik components).

  • You may want to match the decimal places available in the Format and in the Decimals parameters. This will unify the rounding of the numbers when the input is focused and when it is not. For example, if you start with a value 12.3m and Step=0.1m it will render as 12.3 due to the Math.Round() behavior in .NET. Changing the value with the spinner icons up and then down will result in 12.30 because the value had had a second decimal digit at some point and that precision is added to the number already.

    Here is an example of matching the decimal places:

    Razor

    @DecimalStepValue.ToString("N2") <br />
    
    <TelerikNumericTextBox @bind-Value=@DecimalStepValue 
                           Step="0.01m" 
                           Decimals="2" 
                           Format="N2">
    </TelerikNumericTextBox>
    
    @code {
        decimal DecimalValue = 12.3m;
    }
    

Next Steps

See Also

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