/// <summary>
/// Adds a mapping to relate members of one spreadsheet to another by way of a selection query
/// </summary>
/// <typeparam name="TSheetData">Class type to return row data as</typeparam>
/// <typeparam name="TSheetData2">Class of mapped type</typeparam>
/// <param name="property">Lambda expression that selects the List property to set</param>
/// <param name="transformation">Lambda expression that selects members from the second worksheet to relate to the first</param>
/// <param name="worksheet">optional worksheet name</param>
/// <example>
/// AddMapping{Group,People}(g => g.GroupMembers, (g,pp) => pp.Where(p => p.GroupId == g.Id);
/// </example>
public void AddMapping <TSheetData, TSheetData2>(
Expression <Func <TSheetData, IList <TSheetData2> > > property,
Func <TSheetData, IQueryable <TSheetData2>, IQueryable <TSheetData2> > transformation,
string worksheet = null) where TSheetData : class
{
Func <object, IQueryable, IQueryable> function = (t1, qt2) => GetFunction <TSheetData, TSheetData2>(t1, qt2, transformation);
// Add the boxing operation, but get a weakly typed expression
Expression converted = Expression.Convert(property.Body, typeof(object));
// Use Expression.Lambda to get back to strong typing
var keyProperty = Expression.Lambda <Func <TSheetData, object> >(converted, property.Parameters);
var tk = GetTransformKey(keyProperty);
worksheet = worksheet ?? tk.Item2;
var sheetData2Query = this.Worksheet <TSheetData2>(worksheet);
_sheetDataIncludes.Add(TransformKey.Create(typeof(TSheetData2), worksheet), sheetData2Query);
_foreignKeyTransformations.Add(tk, Tuple.Create(worksheet, function));
}
private TransformKey GetTransformKey <TSheetData>(Expression <Func <TSheetData, object> > property)
{
return(TransformKey.Create(typeof(TSheetData), GetPropertyName(property)));
}