/// <summary>
/// Create a fields parameter
/// </summary>
/// <param name="documentSearch">Document search engine</param>
/// <param name="conditional">Conditional to add parameter</param>
/// <param name="fieldExpressions">Expressions used to find fields name</param>
/// <returns>Document search engine</returns>
public static DocumentSearch <TDocument> FieldsIf <TDocument>(this DocumentSearch <TDocument> documentSearch, Func <bool> conditional, params Expression <Func <TDocument, object> >[] fieldExpressions)
where TDocument : Document
{
Checker.IsNull(conditional);
if (conditional.Invoke())
{
documentSearch.Fields(fieldExpressions);
}
return(documentSearch);
}