How to refactor this code?

Question

how can i refactor this code down to one method or something?

            if (!string.IsNullOrEmpty(_gridModel.Header))
                _gridModel.Header += ",";
            if (item != null)
                _gridModel.Header += item.Header;

            if (!string.IsNullOrEmpty(_gridModel.Width))
                _gridModel.Width += ",";
            if (item != null)
                _gridModel.Width += item.Width;

            if (!string.IsNullOrEmpty(_gridModel.Align))
                _gridModel.Align += ",";
            if (item != null)
                _gridModel.Align += item.Align;

            if (!string.IsNullOrEmpty(_gridModel.Filter))
                _gridModel.Filter += ",";
            if (item != null)
                _gridModel.Filter += item.Filter;

            if (!string.IsNullOrEmpty(_gridModel.Type))
                _gridModel.Type += ",";
            if (item != null)
                _gridModel.Type += item.Type;

            if (!string.IsNullOrEmpty(_gridModel.Sort))
                _gridModel.Sort += ",";
            if (item != null)
                _gridModel.Sort += item.Sort;

Answer 1

To start, refactor the logic into a function.

_gridModel.Header = AppendItem(_gridModel.Header, item == null ? null : item.Header);
_gridModel.Width = AppendItem(_gridModel.Width, item == null ? null : item.Width);
...
...

string AppendItem(string src, string item)
{
 if (! string.IsNullOrEmpty(src))
  src += ",";
 if (! string.IsNullOrEmpty(item))
  src += item;
 return src;
}

A good next step could be to use reflection and properties:

Edit: Fleshed out reflection solution, haven't actually debugged it yet though.

AppendProperties(_gridModel, item, "Header", "Width", "Align", ...)

void AppendProperty(object gridmodel, object item, params string[] propNames)
{
    foreach (string propName in propNames)
        AppendProperties(gridmodel, item, propName);
}

void AppendProperties(object gridmodel, object item, string propName)
{
    PropertyInfo piGrid = gridmodel.GetType().GetProperty(propName);
    if (piGrid != null && piGrid.PropertyType == typeof(string))
    {
        piGrid.SetValue(gridmodel, 
            piGrid.GetValue(gridmodel, null).ToString() + ",", null);
    }

    if (item == null) return;
    PropertyInfo piItem = item.GetType().GetProperty(propName);
    if (piItem != null)
    {
        piGrid.SetValue(gridmodel, 
            piGrid.GetValue(gridmodel, null).ToString() 
            + piItem.GetValue(item, null).ToString(), 
            null);
    }
}

Answer 2

Assuming you have .NET 3.5:

string Filter(string input, SomeType item, Func<SomeType, string> extract)
{
    if (!String.IsNullOrEmpty(input))
    {
        if (item == null) return ",";
        else return "," + extract(item);
    }
}

_gridModel.Header += Filter(_gridModel.Header, item, i => i.Header);
_gridModel.Width += Filter(_gridModel.Width, item, i => i.Width);
_gridModel.Align += Filter(_gridModel.Align, item, i => i.Align);

// etc...