Best practice to check if DataRow contains a certain column

Question

At the moment, when I iterate over the DataRow instances, I do this.

foreach(DataRow row in table)
  return yield new Thingy { Name = row[\"hazaa\"]         


        

Answer 1

To build on the answer by Varun K, use a generic type parameter:

public static T GetValue<T>(this DataRow row, string column)
{
    if (!row.Table.Columns.Contains(column))
        return default(T);

    object value = row[ColumnName];
    if (value == DBNull.Value)
        return default(T);
    return (T)value;
}

Answer 2

You can create an extension method to make it cleaner:

static class DataRowExtensions
{
    public static object GetValue(this DataRow row, string column)
    {
        return row.Table.Columns.Contains(column) ? row[column] : null;
    }
}

Now call it like below:

foreach(DataRow row in table)
    return yield new Thingy { Name = row.GetValue("hazaa") };

Answer 3

As your DataTable table always has the same columns ( they won`t change for any row ) you only need to check for the columnname once.

if (table.Columns.Contains("donkey"))
{
    foreach ...
}

Answer 4

foreach (DataColumn item in row.Table.Columns)
{
    switch (item.ColumnName)
    {
        case "ID":
            {
                p.ID = Convert.ToInt32(row[item.ColumnName].ToString());
            }
            break;
        case "firstName":
            {
                p.firstName = row[item.ColumnName].ToString();
            }
            break;
        case "lastName":
            {
                p.lastName = row[item.ColumnName].ToString();
            }
            break;

        default:
            break;
    };
}

Answer 5

Sometimes a column name might exist, but a row does not contain the data for that column; for example, after filling DataTable using ReadXML.

A simple, fast and secure solution would be to use type checking:

if(row["columnname"].GetType() != typeof(System.DBNull)){
    //DataRow contains "columname"
}else{
    //a safe scope to set default cell data
}