IsRootCause return true if the cause of the given error is the same type as mytype.

NewValidationErrors return an empty ValidationErrors struct.

RootCause returns the cause of an errors stack, whatever the method they used to be stacked: either errgo.Notef or errors.Wrapf.

ValidationErrors store each errors associated to every fields of a model.

ValidationErrorsBuilder is used to provide a simple way to create a ValidationErrors struct.