/// <summary>
/// Adds an explicit view model-level validation error (with the given
/// <paramref name="errorMessage"/> to the current VM if any of its
/// properties are invalid (see remarks).
/// </summary>
/// <remarks>
/// This rule is useful if a VM is displayed in a grid where not all
/// properties are visible in the grid. If any of the properites of a
/// VM (visible or not) become invalid, a view model-level (row level)
/// validation error is added to the VM (which is for example visualized
/// by a red cross to the left of the grid row). This indicates to the
/// user that something currently not visible may be invalid and that he
/// or she should open the details of the current record to correct the
/// validation error.
/// </remarks>
public static void ValidateProperties <TOwnerVM, TTargetVM, TDescriptor>(
this ValidatorBuilder <TOwnerVM, TTargetVM, TDescriptor> builder,
string errorMessage
)
where TOwnerVM : IViewModel
where TTargetVM : IViewModel
where TDescriptor : class, IVMDescriptor
{
builder.CheckViewModel((args) => {
if (!args.Owner.Kernel.GetValidationResult(ValidationResultScope.PropertiesOnly).IsValid)
{
args.AddError(errorMessage);
}
});
}
/// <summary>
/// Adds an expli1cit view model-level validation error (with the given
/// <paramref name="errorMessage"/>) to the current VM if any of its
/// descendants are invalid (see remarks).
/// </summary>
/// <remarks>
/// <para>Beware that the validation state is always propagated to to the
/// parent (meaning that <see cref="ViewModel{TDescriptor}.IsValid"/> returns false
/// if any descendant is invalid) but <see cref="ViewModel{TDescriptor}.GetValidationResult(ValidationResultScope)"/>
/// with <see cref="ValidationResultScope.Self"/> does not return an error
/// by default unless you add this validation rule.</para>
/// <para>This validation rule is most useful in hierarchical data structures
/// (e.g. an employee has projects which have tasks which have records) to
/// guide the user to the (probably not visible) record that is actually
/// invalid.</para>
/// </remarks>
public static void PropagateChildErrors <TOwnerVM, TTargetVM, TDescriptor>(
this ValidatorBuilder <TOwnerVM, TTargetVM, TDescriptor> builder,
string errorMessage
)
where TOwnerVM : IViewModel
where TTargetVM : IViewModel
where TDescriptor : class, IVMDescriptor
{
builder.CheckViewModel((args) => {
// TODO: Write test to verify that target is used instead of owner.
if (!args.Target.Kernel.GetValidationResult(ValidationResultScope.Descendants).IsValid)
{
args.AddError(errorMessage);
}
});
}