LengthValidator component

This article demonstrates how to use RadzenLengthValidator.

Basic usage

RadzenLengthValidator checks if the user input is within specified length.

To use it perform these steps:

1. Add an input component and set its Name. Data-bind its value to a model property via @bind-Value=@model.FirstName.
2. Add RadzenLengthValidator and set its Component property to the Name of the input component. Set Min, Max or both to specify the valid string length.

Important

RadzenLengthValidator works only inside RadzenTemplateForm.

<RadzenTemplateForm TItem="Registration" Data=@model>
    <p>
      <RadzenTextBox style="display: block" Name="FirstName" @bind-Value=@model.FirstName />
      <RadzenLengthValidator Component="FirstName" Min="3" Text="First name should be at least 3 characters" />
      <RadzenLengthValidator Component="FirstName" Max="10" Text="First name should be at most 10 characters" />
    </p>
    <RadzenButton ButtonType="ButtonType.Submit" Text="Submit"></RadzenButton>
</RadzenTemplateForm>
@code {
    class Registration
    {
        public string FirstName { get; set; }
    }

    Registration model = new Registration();
}

Conditional validation

To make the validator conditional you can set its Visible property. When set to false the validator will not run.

Appearance

By default RadzenLengthValidator appears next to the component it validates.

To make it appear below set its Style to "display:block".

<RadzenTextBox Name="FirstName" @bind-Value=@model.FirstName />
<RadzenLengthValidator Style="display:block" Component="FirstName" Min="3" Text="First name should be at least 3 characters" />

To make it appear as a styled popup set its Popup property to true and set its CSS position to absolute. The validated component should have display: block so the validation message appears right below it.

<RadzenTextBox Name="FirstName" @bind-Value=@model.FirstName Style="display:block" />
<RadzenLengthValidator Popup="true" Style="position:absolute" Component="FirstName" Min="3" Text="First name should be at least 3 characters" />