protected virtual object GetDataSourceValue(DataTable table, DataRow row, CancellationToken cancel, IProgress <ExecutionProgress> progress)
{
string filterExpression = string.Empty;
for (int criteriaIndex = 0; criteriaIndex < LookupCriteria.Count; criteriaIndex++)
{
LookupCriteria lookupCriteria = LookupCriteria[criteriaIndex];
object filterValue = lookupCriteria.GetValue(row, cancel, progress);
if (filterValue == null)
{
return(null); // todo - we can't look up a null value as part of a lookup at this stage
}
if (filterValue is string)
{
filterValue = ((string)filterValue).Replace("'", "''");
}
if (filterValue is string || filterValue is Guid || filterValue is DateTime)
{
filterValue = string.Concat("'", filterValue, "'");
}
filterExpression = string.Concat(filterExpression, string.Format("{0}{1}{2}{3}", criteriaIndex == 0 ? string.Empty : " AND ", lookupCriteria.SourceField.ColumnName, lookupCriteria.ComparisonOperator == ComparisonOperator.DoesNotEqual ? "<>" : "=", filterValue));
}
string queryDescription = string.Format("{0} records with {1}", DataSource.Name, filterExpression);
string sort = string.Empty;
if (OrderByField != default(DataTableField))
{
sort = string.Format("{0} {1}", OrderByField.ColumnName, ColumnOrder == ColumnOrder.Ascending ? "ASC" : "DESC");
}
object value = default(object);
List <DataRow> rows = table.Select(filterExpression, sort).ToList(); // todo - could cause error if data table is null
if (rows.Count == 1 || (rows.Count > 1 && DuplicateBehaviour == DuplicateBehaviour.First))
{
value = Convert(rows[0][ValueField.ColumnName]);
}
else if (rows.Count > 1 && DuplicateBehaviour == DuplicateBehaviour.Error)
{
throw new DuplicateLookupValueException(string.Format("Matched {0} {1}", rows.Count, queryDescription), this);
}
else if (rows.Count == 0 && NotFoundBehaviour == NotFoundBehaviour.Error)
{
throw new MissingLookupValueException(string.Format("No {0} could be found", queryDescription), this);
}
return(value);
}
public virtual LookupCriteria Clone()
{
LookupCriteria clone = (LookupCriteria)MemberwiseClone();
return(clone);
}
