CompareValidator

The CompareValidator component validates user input by comparing it to a constant value or to the value of another control using a comparison operator (equals, greater than, less than, etc.). Original Web Forms documentation is at: https://docs.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.comparevalidator?view=netframework-4.8

Blazor Features Supported

• Comparison operators: Equal, NotEqual, GreaterThan, GreaterThanEqual, LessThan, LessThanEqual, DataTypeCheck
• Data type validation: String, Integer, Double, Date, Currency
• ValueToCompare property for comparing against a constant value
• CultureInvariantValues for culture-independent comparisons
• ErrorMessage display when validation fails
• Integration with EditForm validation

WebForms Features Not Supported

• ControlToCompare is not directly supported; use ValueToCompare with binding instead
• Display property (Static, Dynamic, None) - Blazor handles rendering differently
• SetFocusOnError - Blazor has different focus management

WebForms Syntax

<asp:CompareValidator
    ControlToCompare="string"
    ControlToValidate="string"
    CultureInvariantValues="True|False"
    Display="None|Static|Dynamic"
    EnableClientScript="True|False"
    Enabled="True|False"
    ErrorMessage="string"
    ForeColor="color name|#dddddd"
    ID="string"
    Operator="Equal|NotEqual|GreaterThan|GreaterThanEqual|LessThan|
        LessThanEqual|DataTypeCheck"
    runat="server"
    SetFocusOnError="True|False"
    Text="string"
    Type="String|Integer|Double|Date|Currency"
    ValidationGroup="string"
    ValueToCompare="string"
    Visible="True|False"
/>

Blazor Syntax

<CompareValidator TValue="string"
    ValueToCompare="100"
    Operator="ValidationCompareOperator.GreaterThan"
    Type="ValidationDataType.Integer"
    ErrorMessage="Value must be greater than 100"
    @ref="myValidator" />

Usage Notes

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

Example: Comparing to a Constant Value

<EditForm Model="@model">
    <InputNumber @bind-Value="model.Age" />
    <CompareValidator TValue="int"
        ValueToCompare="18"
        Operator="ValidationCompareOperator.GreaterThanEqual"
        Type="ValidationDataType.Integer"
        ErrorMessage="You must be at least 18 years old" />
</EditForm>

Supported Operators

Operator	Description
Equal	Values must be equal
NotEqual	Values must not be equal
GreaterThan	Input must be greater than comparison value
GreaterThanEqual	Input must be greater than or equal to comparison value
LessThan	Input must be less than comparison value
LessThanEqual	Input must be less than or equal to comparison value
DataTypeCheck	Validates that input can be converted to the specified data type

Supported Data Types

Type	Description
String	Text comparison
Integer	Whole number comparison
Double	Decimal number comparison
Date	Date comparison
Currency	Currency value comparison