public static bool DiffWith(this DataTable first, DataTable second, IEnumerable <string> primaryKeyColumns, IEnumerable <string> valueColumns, out DataTable matches)
{
matches = new DataTable();
matches.Columns.Add("PkeyDelta", typeof(int));
matches.Columns.Add("ValueDelta", typeof(int));
matches.Columns.Add("OldRow", typeof(DataRow));
matches.Columns.Add("NewRow", typeof(DataRow));
bool ret = false;
var firstRows = first.GetRows();
var secondRows = second.GetRows();
var f = firstRows.ToList();
var s = secondRows.ToList();
string[] pkeyColumnNames = primaryKeyColumns.ToArray();
string[] valueColumnNames = valueColumns.ToArray();
var secondIndex = new TableIndex(second);
Dictionary <DataRow, object> assertDictionary1 = first.GetRows().ToDictionaryDX(NULL); //these are to make sure no records are missing/lost/double removed/etc.
Dictionary <DataRow, object> assertDictionary2 = second.GetRows().ToDictionaryDX(NULL);
for (int pkeyDelta = 0; pkeyDelta < primaryKeyColumns.Count(); pkeyDelta++)
{
for (int valueDelta = 0; valueDelta < valueColumns.Count(); valueDelta++)
{
List <int> removals = new List <int>();
for (int i = 0; i < f.Count; i++)
{
var frow = f[i];
DataRow found = FindFuzzyMatch(frow, pkeyDelta, valueDelta, pkeyColumnNames, valueColumnNames, secondIndex);
if (found != null)
{
matches.Rows.Add(pkeyDelta, valueDelta, frow, found);
assertDictionary2.Remove(found);
secondIndex.Remove(found);
removals.Add(i);
}
}
for (int i = removals.Count - 1; i >= 0; i--)
{
assertDictionary1.Remove(f[removals[i]]);
f.RemoveAt(removals[i]);
}
if (pkeyDelta == 0 && valueDelta == 0 && assertDictionary1.Count == 0 && assertDictionary2.Count == 0)
{
ret = true;
}
}
}
for (int i = 0; i < f.Count; i++)
{
matches.Rows.Add(-1, -1, f[i], null);
assertDictionary1.Remove(f[i]);
}
for (int i = 0; i < s.Count; i++)
{
matches.Rows.Add(-1, -1, null, s[i]);
assertDictionary2.Remove(s[i]);
}
Debug.Assert(assertDictionary1.Count == 0);
Debug.Assert(assertDictionary2.Count == 0);
return(ret);
}