将一般列表/可枚举DataRow添加到DataTable？

Question

I am trying to write a function which takes generic List/Enumerable and add DataRow to existing DataTable but only for Custom Columns.

public void AddGridRow<T>(IEnumerable<T> rowData, params String[] columnNames)
{
  HashSet<String> columnsHashSet = new HashSet<String>(columnNames);

  PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
  foreach (T item in rowData)
  {
      foreach (PropertyDescriptor prop in properties)
      {
         foreach (DataColumn column in _dataGridTable.Columns)
         {
             DataRow newRow = _dataGridTable.NewRow();
             if (columnsHashSet.Contains(prop.Name))
             {
                 newRow[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
                 _dataGridTable.Rows.Add(newRow); // _dataGridTable is my existing DataTable
                break;
             }
          }
       }
   }
}

Now the problem is it is not behaving correctly, lets say I have to add 1 row in 4 columns (columnNames), it is adding the 1 Row per columns. Also there are far many foreach loops. How can I correct this and if possible optimize it.

Answer 1

You need to move the "_dataGridTable.Rows.Add(newRow);" line outside of the inner foreach loop:

foreach (T item in rowData)
  {
      foreach (PropertyDescriptor prop in properties)
      {
         DataRow newRow = _dataGridTable.NewRow();
         foreach (DataColumn column in _dataGridTable.Columns)
         {
             if (columnsHashSet.Contains(prop.Name))
             {
                 newRow[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
                break;
             }
          }
       }
      _dataGridTable.Rows.Add(newRow); // _dataGridTable is my existing DataTable
   }