public static ValidationErrors If(
this ValidationErrors source,
bool predicate,
ValidationError validationError)
{
return(predicate ?
source.With(validationError) :
source);
}
public static ValidationErrors Require <TValue>(
this ValidationErrors source,
TValue value,
string name)
{
var valueType = typeof(TValue);
var enumerableInterface = valueType
.GetInterfaces()
.FirstOrDefault(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IReadOnlyCollection <>));
var missing = false;
if (value is string str)
{
missing = string.IsNullOrWhiteSpace(str);
}
else if (valueType == typeof(Guid?))
{
var g = (Guid?)(object)value;
missing = !g.HasValue || g.Value == Guid.Empty;
}
else if (value == null)
{
missing = true;
}
else if (enumerableInterface != null)
{
missing = (int)valueType.GetProperty(nameof(IReadOnlyCollection <object> .Count)).GetValue(value) == 0;
}
else
{
missing = value.IsDefaultValue();
}
return(missing ?
source.With(ValidationError.Required(name)) :
source);
}