/// <summary>
/// Parse traditional SQL order-by statement into a SortKeyList.
/// </summary>
/// <remarks><para>The order-by input is a comma separated string of fields names with added direction keywords.
/// For instance "Title, Age desc". The field names are case-sensitive whereas the direction keywords are case-insensitive.
/// Possible values for the direction keywords are "ascending", "descending", "asc", "desc".</para>
/// <para>Developers should actually try to avoid using this method. It is primarily here to connect GUI and code where the GUI
/// cannot produce the <c>Func<TSource,object></c> objects directly.</para></remarks>
/// <param name="orderBy">Order-by string.</param>
/// <returns>A SortKeyList representing the order-by string.</returns>
public static SortKeyList <TSource> CreateKeyList(string orderBy)
{
SortKeyList <TSource> list = new SortKeyList <TSource>();
if (orderBy == null)
{
return(list);
}
orderBy = orderBy.Trim();
if (orderBy.Length == 0)
{
return(list);
}
string[] parts = orderBy.Split(',');
Type sourceType = typeof(TSource);
foreach (string part in parts)
{
string[] keydir = part.Trim().Split(' ');
string key = keydir[0].Trim();
string dirstr = (keydir.Length > 1 ? keydir[1].Trim() : null);
SortKeyDirection dir = ParseDirection(dirstr);
list.AddKey(dir, ParseFieldReference(sourceType, key));
}
return(list);
}
public static SortKeyList <TSource> CreateKeyList(SortKeyDirection direction, Expression <Func <TSource, object> > key)
{
SortKeyList <TSource> list = new SortKeyList <TSource>();
list.Add(new SortKey <TSource>(direction, key));
return(list);
}
protected static SortKeyDirection ParseDirection(string dirstr)
{
SortKeyDirection dir = SortKeyDirection.Ascending;
if (string.IsNullOrEmpty(dirstr))
{
return(dir);
}
if (dirstr.ToLower() == "desc" || dirstr.ToLower() == "descending")
{
dir = SortKeyDirection.Descending;
}
else if (dirstr.ToLower() != "asc" && dirstr.ToLower() != "ascending")
{
throw new ArgumentException(string.Format("Unknown direction keyword '{0}'", dirstr));
}
return(dir);
}
public SortKey(SortKeyDirection direction, Expression <Func <TSource, object> > key)
{
Direction = direction;
Key = key;
}
public SortKeyList <TSource> AddKey(SortKeyDirection direction, Expression <Func <TSource, object> > key)
{
Add(new SortKey <TSource>(direction, key));
return(this);
}
