Checking to see if a column exists in a data reader [duplicate]

Answer 1

I ended up finding a solution using the reader.GetName(int) method. I created the below method to encompass the logic.

public bool ColumnExists(IDataReader reader, string columnName)
{
    for (int i = 0; i < reader.FieldCount; i++)
    {
         if (reader.GetName(i).Equals(columnName, StringComparison.InvariantCultureIgnoreCase))
        {
            return true;
        }
    }

    return false;
}

Answer 2

Load it into a DataTable and then you can check for column:

DataTable dataTable = new DataTable();
dataTable.Load(reader);
foreach (var item in dataTable.Rows) 
{
    bool columnExists = item.Table.Columns.Contains("ColumnName");
}

Answer 3

Enumerable.Range(0, reader.FieldCount).Any(i => reader.GetName(i) == "ColumnName")

Answer 4

Appears I stand corrected. I know your actual column names are in there, but I was going down the wrong path. This reference helped clear things up a bit, but I'm still not sure if there's an elegant way of doing it. Adapted from the above link, you could get a list of all of your columns with the following:

List<string> myCols = new List<string>();
DataTable schema = reader.GetSchemaTable();
foreach (DataRow row in schema.Rows)
{
    myCols.Add(row[schema.Columns["ColumnName"]]);
}

Unfortunately it appears you can only access schema.Rows by index, so I'm not sure you can get around looping through the rows first before checking by name. In that case, your original solution seems far more elegant!

Note: my original answer suggested checking for presence of a column simply by: reader.GetSchemaTable().Columns["optionalfield"].

Answer 5

This should work, try this:

private static bool ColumnExists(SqlDataReader reader, string columnName)
        {
            using (var schemaTable = reader.GetSchemaTable())
            {
                if (schemaTable != null)
                    schemaTable.DefaultView.RowFilter = String.Format("ColumnName= '{0}'", columnName);

                return schemaTable != null && (schemaTable.DefaultView.Count > 0);
            }
        }

Answer 6

Don't need so much complication, just this:

bool bFieldExists = datareader.GetSchemaTable().Columns.Contains(strFieldName);