/// <summary>
/// Answers whether the data in the column named columnName in the child table all have the same value.
/// </summary>
/// <param name="ds">The Dataset</param>
/// <param name="relationName">The index of the parent row which is being considered for this check.</param>
/// <param name="parentRowIndex">The name of the relation between the parent and child table. </param>
/// <param name="columnName">The DataColumn to look for</param>
/// <param name="ignoreNullCells">Should we ignore NULL cells</param>
/// <returns></returns>
public static bool columnInChildRowsHaveSameValue(DataSet ds, string relationName, int parentRowIndex,
string columnName, bool ignoreNullCells)
{
bool haveSameValue = true;
DataRelation dataRelation = ds.Relations[relationName];
// get the child rows which correspond to the parent row
DataRow[] childRowsArray = dataRelation.ParentTable.Rows[parentRowIndex].GetChildRows(relationName);
IEnumerator childRowsCollection = childRowsArray.GetEnumerator();
if (childRowsArray.Length < 1)
{
// special case
// (from bug 267)
// it appears that if one tries to group by one or more columns and all child rows happen to have DBNull in the corresponding
// columns that GetChildRows will not find any matching child rows (when it seems that it should have returned all rows)
// Under these circumstances we'll try to do a select distinct on the grouping columns and, if we get exactly one data item
// back, we'll set the childRowsArray equal to all of the rows in the child table.
// a better solution would be to somehow involve the GetChildRows call directly but I didn't find anything in my
// web searching which talked about this situation.
DataSetHelper dsh = new DataSetHelper();
DataTable distinctValuesTable = dsh.SelectDistinct("distinctChildValues", dataRelation.ChildTable, columnName);
if (distinctValuesTable.Rows.Count > 0)
{
childRowsCollection = dataRelation.ChildTable.Rows.GetEnumerator(); // select everything
}
else
{
throw new ApplicationException("No child rows for relation name [" + relationName + "] parent row index [" +
parentRowIndex + "]");
}
}
// finally check for matching value of the column within all the child rows.
object firstCellValue = null;
bool firstCellValueWasSet = false;
DataRow childRow;
while (childRowsCollection.MoveNext())
{
childRow = (DataRow)childRowsCollection.Current;
if (!firstCellValueWasSet)
{
if (((isNull(childRow[columnName])) && (!ignoreNullCells)) ||
(!isNull(childRow[columnName])))
{
firstCellValue = childRow[columnName];
firstCellValueWasSet = true;
}
}
else
{
if (isNull(childRow[columnName]))
{
if (!ignoreNullCells)
{
if (!isNull(firstCellValue))
{
haveSameValue = false;
break;
}
}
}
else
{
if (!firstCellValue.Equals(childRow[columnName]))
{
haveSameValue = false;
break;
}
}
}
}
return(haveSameValue);
}
/// <summary>
/// Answers whether the data in the column named columnName in the child table all have the same value.
/// </summary>
/// <param name="ds">The Dataset</param>
/// <param name="relationName">The index of the parent row which is being considered for this check.</param>
/// <param name="parentRowIndex">The name of the relation between the parent and child table. </param>
/// <param name="columnName">The DataColumn to look for</param>
/// <param name="ignoreNullCells">Should we ignore NULL cells</param>
/// <returns></returns>
public static bool columnInChildRowsHaveSameValue(DataSet ds, string relationName, int parentRowIndex,
string columnName, bool ignoreNullCells)
{
bool haveSameValue = true;
DataRelation dataRelation = ds.Relations[relationName];
// get the child rows which correspond to the parent row
DataRow[] childRowsArray = dataRelation.ParentTable.Rows[parentRowIndex].GetChildRows(relationName);
IEnumerator childRowsCollection = childRowsArray.GetEnumerator();
if (childRowsArray.Length < 1)
{
// special case
// (from bug 267)
// it appears that if one tries to group by one or more columns and all child rows happen to have DBNull in the corresponding
// columns that GetChildRows will not find any matching child rows (when it seems that it should have returned all rows)
// Under these circumstances we'll try to do a select distinct on the grouping columns and, if we get exactly one data item
// back, we'll set the childRowsArray equal to all of the rows in the child table.
// a better solution would be to somehow involve the GetChildRows call directly but I didn't find anything in my
// web searching which talked about this situation.
DataSetHelper dsh = new DataSetHelper();
DataTable distinctValuesTable = dsh.SelectDistinct("distinctChildValues", dataRelation.ChildTable, columnName);
if (distinctValuesTable.Rows.Count > 0)
{
childRowsCollection = dataRelation.ChildTable.Rows.GetEnumerator(); // select everything
}
else
{
throw new ApplicationException("No child rows for relation name [" + relationName + "] parent row index [" +
parentRowIndex + "]");
}
}
// finally check for matching value of the column within all the child rows.
object firstCellValue = null;
bool firstCellValueWasSet = false;
DataRow childRow;
while (childRowsCollection.MoveNext())
{
childRow = (DataRow) childRowsCollection.Current;
if (!firstCellValueWasSet)
{
if ( ( (isNull(childRow[columnName])) && (!ignoreNullCells) )
|| (!isNull(childRow[columnName])))
{
firstCellValue = childRow[columnName];
firstCellValueWasSet = true;
}
}
else
{
if (isNull(childRow[columnName]))
{
if (!ignoreNullCells)
{
if (!isNull(firstCellValue))
{
haveSameValue = false;
break;
}
}
}
else
{
if (!firstCellValue.Equals(childRow[columnName]))
{
haveSameValue = false;
break;
}
}
}
}
return haveSameValue;
}
