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RangeValidator.md

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RangeValidator

The RangeValidator component validates that user input falls within a specified range of values. This is useful for ensuring numeric values, dates, or strings are within acceptable bounds. Original Web Forms documentation is at: https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.rangevalidator?view=netframework-4.8

Features Supported in Blazor

  • MinimumValue and MaximumValue range boundaries
  • Data type validation: String, Integer, Double, Date, Currency
  • CultureInvariantValues for culture-independent comparisons
  • ErrorMessage display when validation fails
  • Integration with EditForm validation

Web Forms Features NOT Supported

  • Display property (Static, Dynamic, None) - Blazor handles rendering differently
  • SetFocusOnError - Blazor has different focus management
  • EnableClientScript - Blazor uses its own validation model

Syntax Comparison

=== "Web Forms"

```html
<asp:RangeValidator
    ControlToValidate="string"
    CultureInvariantValues="True|False"
    Display="None|Static|Dynamic"
    EnableClientScript="True|False"
    Enabled="True|False"
    ErrorMessage="string"
    ForeColor="color name|#dddddd"
    ID="string"
    MaximumValue="string"
    MinimumValue="string"
    runat="server"
    SetFocusOnError="True|False"
    Text="string"
    Type="String|Integer|Double|Date|Currency"
    ValidationGroup="string"
    Visible="True|False"
/>
```

=== "Blazor"

```razor
<RangeValidator TValue="string"
    MinimumValue="1"
    MaximumValue="100"
    Type="ValidationDataType.Integer"
    ErrorMessage="Value must be between 1 and 100" />
```

Usage Notes

The RangeValidator is a generic component that takes a type parameter TValue. It inherits from BaseCompareValidator which provides the core comparison logic.

Example: Validating a Numeric Range

<EditForm Model="@model">
    <InputNumber @bind-Value="model.Quantity" />
    <RangeValidator TValue="int"
        MinimumValue="1"
        MaximumValue="999"
        Type="ValidationDataType.Integer"
        ErrorMessage="Quantity must be between 1 and 999" />
</EditForm>

Example: Validating a Date Range

<EditForm Model="@model">
    <InputDate @bind-Value="model.BirthDate" />
    <RangeValidator TValue="DateTime"
        MinimumValue="1/1/1900"
        MaximumValue="12/31/2010"
        Type="ValidationDataType.Date"
        ErrorMessage="Birth date must be between 1900 and 2010" />
</EditForm>

Supported Data Types

Type Description
String Alphabetical string comparison
Integer Whole number range validation
Double Decimal number range validation
Date Date range validation
Currency Currency value range validation

Behavior Notes

  • Empty or null values pass validation (use RequiredFieldValidator in combination if the field is required)
  • Whitespace-only values pass validation
  • Both MinimumValue and MaximumValue boundaries are inclusive

Migration Notes

  1. Remove asp: prefix — Change <asp:RangeValidator> to <RangeValidator>
  2. Remove runat="server" — Not needed in Blazor
  3. Add generic type parameter — Use TValue="int" or TValue="DateTime" etc.
  4. Type uses enum — Change Type="Integer" to Type="ValidationDataType.Integer"
  5. Remove EnableClientScript — Not applicable in Blazor
  6. Remove SetFocusOnError — Not supported in Blazor

Migration Example

=== "Web Forms"

```html
<asp:TextBox ID="txtQty" runat="server" />
<asp:RangeValidator
    ControlToValidate="txtQty"
    MinimumValue="1"
    MaximumValue="999"
    Type="Integer"
    ErrorMessage="Quantity must be between 1 and 999"
    runat="server" />
```

=== "Blazor"

```razor
<InputNumber @bind-Value="model.Quantity" />
<RangeValidator TValue="int"
    ControlToValidate="Quantity"
    MinimumValue="1"
    MaximumValue="999"
    Type="ValidationDataType.Integer"
    ErrorMessage="Quantity must be between 1 and 999" />
```

See Also