ADO.NET DataRow - check for column existance

Question

How do I check for the existence of a column in a datarow? I'm building datatables to organize some data that I've already pulled back from the db. Depending on the type of data in each row I need to create a datatable with different columns. Then later on I want to check and see if the datatable i am looking at has a certain column. I know I can catch the exception and handle it that way, but I'm curious if there is a property or method on the datarow object that will do this for me?

Here's how I can do it by catching the exception:

public static String CheckEmptyDataRowItem(DataRow row, String rowName, String nullValue)
{
    try
    {
        return row[rowName].ToString();
    }
    catch (System.ArgumentException)
    {
        return nullValue;
    }
}

Answer 1

DataTables have that schema info, so check if the Row's Table's Columns collection contains the field.

Answer 2

There is no property supplied by the framework that will do this. You can however accomplish this without adding a try/catch that will regularly catch into the logical execution.

Use a DataTableReader object to read the table hosting the row. You can generate the reader from the properties in the row itself. The reader object provides the required functions to verify if a column exists.

Try something along the lines of:

public static bool DoesColumnExistInRow(DataRow row, string columnName)
{
   bool output = false;

   DataTableReader reader = null;
   try 
   {
      reader = row.Table.CreateDataReader();
      if (reader.HasRows) 
      {
          reader.Read();
          for (int i = 0; i < reader.FieldCount; i++) 
          {
             if (reader.GetName(i).Equals(columnName)) 
             {
                 output = true;
                 break;
             }       
      }
   }
   catch (Exception ex)
   { 
      // handle any unexpected errors creating the reader
   }
   finally
   {
      if (reader != null) 
      {
         reader.Dispose();
      }
   }

   return output;
}

Answer 3

You can simply check like this:

return (row.Table.Columns.Contains(columnName)) ? true : false;