IDataErrorInfo : How to know if all properties are valid?

idataerrorinfo, validation, wpf

Solution

From your comment on your implementation of `IDataErrorInfo` change your implementation to this style....

#region IDataErrorInfo Members

public string Error
{
    get { return this[null] }
}

public string this[string columnName]
{
    get
    {
        StringBuilder result = new StringBuilder();
        if (string.IsNullOrEmpty(columnName) || columnName == "FirstName")
        {
            if (string.IsNullOrEmpty(FirstName))
                result.Append("Please enter a First Name\n");
        }
        if (string.IsNullOrEmpty(columnName) || columnName == "LastName")
        {
            if (string.IsNullOrEmpty(LastName))
                result.Append("Please enter a Last Name\n");
        }
       if (string.IsNullOrEmpty(columnName) || columnName == "Age")
        {
            if (Age <= 0 || Age >= 99)
                result.Append("Please enter a valid age\n");
        }
        return (result.Length==0) ? null : result.Remove(result.Length-1,1).ToString();
    }
}

#endregion


public bool IsValid {
   get { return string.IsNullOrEmpty(this.Error); }
}

Then in your property changed event

if (e.PropertyName == "Error") {
   OnPropertyChanged(this,new PropertyChangedEventArgs("IsValid"));
}
if (e.PropertyName != "Error" && e.PropertyName != "IsValid") {
   OnPropertyChanged(this,new PropertyChangedEventArgs("Error"));
}

Problem

I have a `WPF` application(`.Net 3.5`) which uses the `IDataErrorInfo` on the ViewModel to validate input. It works great, the usercontrol get the correct UI feedback. The problem is that the user can still change the selected element, or save this element. So my question is: How can I know that all my properties are valid? Or at least that all my displayed values are valid. The goal is to bind some `IsActive` on this result

Original source

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