Disable save button when validation fails

Question

As you can likely see from the title, I am about to ask something which has been asked many times before. But still, after reading all these other questions, I cannot find a

Answer 1

I've implemented the map approach shown in my comment above, in C# this is called a Dictionary in which I am using anonymous methods to do the validation:

partial class Player : IDataErrorInfo
{
    private delegate string Validation(string value);
    private Dictionary columnValidations;
    public List Errors;

    public Player()
    {
        columnValidations = new Dictionary();
        columnValidations["Firstname"] = delegate (string value) {
            return String.IsNullOrWhiteSpace(Firstname) ? "Geef een voornaam in" : null;
        }; // Add the others...

        errors = new List();
    }

    public bool CanSave { get { return Errors.Count == 0; } }

    public string this[string columnName]
    {
        get { return this.GetProperty(columnName); } 

        set
        { 
            var error = columnValidations[columnName](value);

            if (String.IsNullOrWhiteSpace(error))
                errors.Add(error);
            else
                this.SetProperty(columnName, value);
        }
    }
}