ASP .NET MVC 3 Data Annotations GreaterThan LowerThan for DateTime and int

Question

I would like to know what is the easiest way to have a \"Greater Than\" & \"Lower Than\" validation on a ASP.NET MVC 3 form?

I use unobtrusive JavaScript for client

Answer 1

I don't know if writing your own validator class is the "easiest" way, but that's what I did.

Usage:

Public Property StartDate() As DateTime




Public Property EndDate() As DateTime

Class:

Public Class DateGreaterThanEqualAttribute
    Inherits ValidationAttribute

    Public Sub New(ByVal compareDate As String, ByVal errorMessage As String)
        MyBase.New(errorMessage)
        _compareDate = compareDate
    End Sub
    Public ReadOnly Property CompareDate() As String
        Get
            Return _compareDate
        End Get
    End Property
    Private ReadOnly _compareDate As String

    Protected Overrides Function IsValid(ByVal value As Object, ByVal context As ValidationContext) As ValidationResult
        If value Is Nothing Then
            ' no need to do or check anything
            Return Nothing
        End If
        ' find the other property we need to compare with using reflection
        Dim compareToValue = Nothing
        Dim propAsDate As Date
        Try
            compareToValue = context.ObjectType.GetProperty(CompareDate).GetValue(context.ObjectInstance, Nothing).ToString
            propAsDate = CDate(compareToValue)
        Catch
            Try
                Dim dp As String = CompareDate.Substring(CompareDate.LastIndexOf(".") + 1)
                compareToValue = context.ObjectType.GetProperty(dp).GetValue(context.ObjectInstance, Nothing).ToString
                propAsDate = CDate(compareToValue)
            Catch
                compareToValue = Nothing
            End Try
        End Try

        If compareToValue Is Nothing Then
            'date is not supplied or not valid
            Return Nothing
        End If

        If value < compareToValue Then
            Return New ValidationResult(FormatErrorMessage(context.DisplayName))
        End If

        Return Nothing
    End Function

End Class