Disable past dates in datapicker wpf is this possible

I have a datapicker in wpf and I have to disable past dates. I am using a MVVM p开发者_运维技巧attern. Is it possible?

How do you do it?

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You can use the DisplayDateStart and DisplayDateEnd properties of DatePicker. They are dependencies properties so you can supply them via your DataContext using MVVM. Here's the documentation:

• DatePicker.DisplayDateStart Property
• DatePicker.DisplayDateEnd Property

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Additional to Rick's answer, the DisplayDateStart and DisplayDateEnd only affect the calendar, it does not stop the user from typeing a valid date outside this range.

To do this you could throw an exception in the setter in the bound property in your ViewModel or if you are using IDataErrorInfo, return a validation error message via this[string columnName]

ExceptionValidationRule:

<Binding Path="SelectedDate" UpdateSourceTrigger="PropertyChanged"> 
    <Binding.ValidationRules>
      <ExceptionValidationRule />
    </Binding.ValidationRules>
  </Binding>

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You have to set the DisplayDateStart attribute with Today's date

<DatePicker Name="dt_StartDateFrom" DisplayDateStart="{x:Static sys:DateTime.Today}">
</DatePicker>

Make sure you have set the

xmlns:sys="clr-namespace:System;assembly=mscorlib"

in your <UserControl> tag to be able to use the sys: parameter

P.S. To Disable future dates, you can use DisplayDateEnd attribute

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This could be a neater solution if your disabled date ranges involve constants that you want keep in xaml.

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If you are using MVVM we can appy custom attributes to do the validation.

public Class MyModel : INotifyPropertyChanged{

   private DateTime _MyDate;
   [FutureDateValidation(ErrorMessage="My Date should not be greater than current Date")]
   public DateTime Mydate{
       get{return _MyDate;}
       set{
          _Mydate=value;
       }
   }


}

The implementation for the FutureDateValidation will be given as follows

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
    class FutureDateValidationAttribute : ValidationAttribute
    {

        protected override ValidationResult IsValid(object value,ValidationContext validationContext)
        {
            ErrorMessage = ErrorMessageString;
            DateTime inputDateTime = (DateTime)value;
            if (inputDateTime != null)
            {
                if (inputDateTime > DateTime.Now)
                {
                    return new ValidationResult(ErrorMessage);
                }
                else {
                    return null;
                }

            }
            else {
                return null;
            }
        }
    }