IDataReader - GetValueToOrDefault
An IDataReader extension method that gets value to or default.
public static void Main() { const string sql = @"SELECT 1 As IntColumn"; using (var conn = new SqlConnection(FiddleHelper.GetConnectionStringSqlServer())) { conn.Open(); using (DbCommand command = conn.CreateCommand()) { command.CommandText = sql; using (IDataReader reader = command.ExecuteReader()) { while (reader.Read()) { //C# Extension Method: IDataReader - GetValueToOrDefault var result1 = reader.GetValueTo<int>("IntColumn"); var result2 = reader.GetValueToOrDefault<int>("UnknownColumn"); int result3 = reader.GetValueToOrDefault("UnknownColumn", -1); int result4 = reader.GetValueToOrDefault("UnknownColumn", (dataReader, s) => -2); Console.WriteLine(result1); Console.WriteLine(result2); Console.WriteLine(result3); Console.WriteLine(result4); } } } } }
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using System; using System.Data; public static partial class Extensions { /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="index">Zero-based index of the.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, int index) { try { return @this.GetValue(index).To<T>(); } catch { return default(T); } } /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="index">Zero-based index of the.</param> /// <param name="defaultValue">The default value.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, int index, T defaultValue) { try { return @this.GetValue(index).To<T>(); } catch { return defaultValue; } } /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="index">Zero-based index of the.</param> /// <param name="defaultValueFactory">The default value factory.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, int index, Func<IDataReader, int, T> defaultValueFactory) { try { return @this.GetValue(index).To<T>(); } catch { return defaultValueFactory(@this, index); } } /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="columnName">Name of the column.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, string columnName) { try { return @this.GetValue(@this.GetOrdinal(columnName)).To<T>(); } catch { return default(T); } } /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="columnName">Name of the column.</param> /// <param name="defaultValue">The default value.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, string columnName, T defaultValue) { try { return @this.GetValue(@this.GetOrdinal(columnName)).To<T>(); } catch { return defaultValue; } } /// <summary> /// An IDataReader extension method that gets value to or default. /// </summary> /// <typeparam name="T">Generic type parameter.</typeparam> /// <param name="this">The @this to act on.</param> /// <param name="columnName">Name of the column.</param> /// <param name="defaultValueFactory">The default value factory.</param> /// <returns>The value to or default.</returns> public static T GetValueToOrDefault<T>(this IDataReader @this, string columnName, Func<IDataReader, string, T> defaultValueFactory) { try { return @this.GetValue(@this.GetOrdinal(columnName)).To<T>(); } catch { return defaultValueFactory(@this, columnName); } } }