private Expression BuildWriterItem(IMappingAssociation association, Expression from, Expression to, ParameterExpression explicitProperties)
{
if ((association.Direction & MappingDirection.Write) != MappingDirection.Write)
{
return(null);
}
var converter = association as IConvertionAssociation;
var component = association as IComponentAssociation;
var donor = association.Target.Apply(@from);
var acceptor = association.Source.Apply(to);
Expression result;
if (component != null)
{
//todo: probably should filterout expand somehow. E.g. 'foo.id' should become 'id'. Now simply not passing outer expand
result = BuildWriterBody(donor, acceptor, null);
if (result.NodeType == ExpressionType.Default && result.Type == typeof(void))
{
return(null);
}
}
else
{
PropertyInfo prop;
if (!acceptor.TryGetProperty(out prop))
{
throw new InvalidOperationException(
string.Format("Mapping from source:{0} to target:{1} marked as writable but source is not a property access expression", association.Source.Stringify(), association.Target.Stringify())
);
}
result = Expression.Assign(
acceptor,
converter == null ? donor : converter.TargetConverter.Expression.Apply(donor)
);
}
if (!(donor.Type.IsValueType || (result.NodeType == ExpressionType.Assign && ((BinaryExpression)result).Right == donor)))
{
result = Expression.IfThenElse(
donor.CreateCheckForDefault(),
Expression.Assign(acceptor, acceptor.Type.GetDefaultExpression()),
result
);
}
if (explicitProperties != null)
{
result = Expression.IfThen(
Expression.OrElse(
explicitProperties.CreateCheckForDefault(),
explicitProperties.CreateContains(Expression.Constant(association.Key, typeof(string)))
),
result
);
}
return(result);
}