/// <summary>
/// Reads the first column of each row from the query result into a <see cref="HashSet{T}"/>. All other columns are ignored.
/// <para>Valid <typeparamref name="T"/> types: Any .NET built-in type or ADO.NET data provider supported type.</para>
/// </summary>
/// <remarks>
/// Note: <see cref="DBNull"/> values will be excluded.
/// </remarks>
/// <typeparam name="T">The generic type to use.</typeparam>
/// <param name="odr">The <see cref="DbDataReader"/> to use.</param>
/// <param name="token">The <see cref="CancellationToken"/> to use. (Optional)</param>
/// <returns>The <see cref="HashSet{T}"/>.</returns>
/// <exception cref="System.InvalidCastException">Thrown when <typeparamref name="T"/> is not supported.</exception>
public static HashSet <T> ToHashSet <T>(this DbDataReader odr, CancellationToken token = default)
{
HashSet <T> projectedData = new HashSet <T>();
if (odr.HasRows)
{
Type tType = typeof(T);
Type nonNullableObjType = tType.IsValueType ? (Nullable.GetUnderlyingType(tType) ?? tType) : tType;
while (odr.Read())
{
if (token.IsCancellationRequested)
{
return(projectedData);
}
object value = odr.GetValue(0);
if (value != DBNull.Value)
{
projectedData.Add((T)(DbConnectorUtilities.ThrowIfFailedToMatchColumnType(tType, nonNullableObjType, value, () => odr.GetName(0))));
}
}
}
return(projectedData);
}
/// <summary>
/// Reads data into a <see cref="List{T}"/>.
/// <para>Valid <typeparamref name="T"/> types: <see cref="DataSet"/>, <see cref="DataTable"/>, <see cref="Dictionary{string,object}"/>, any .NET built-in type, or any struct or class with a parameterless constructor not assignable from <see cref="System.Collections.IEnumerable"/> (Note: only properties will be mapped).</para>
/// </summary>
/// <typeparam name="T">The generic type to use.</typeparam>
/// <param name="odr">The <see cref="DbDataReader"/> to use.</param>
/// <param name="token">The <see cref="CancellationToken"/> to use. (Optional)</param>
/// <param name="cmd">The <see cref="IDbJobCommand"/> to use for data projection and caching. (Optional)</param>
/// <returns>The <see cref="List{T}"/>.</returns>
/// <exception cref="System.InvalidCastException">Thrown when <typeparamref name="T"/> is missing a parameterless constructor.</exception>
/// <exception cref="System.InvalidCastException">Thrown when <typeparamref name="T"/> is assignable from <see cref="System.Collections.IEnumerable"/>.</exception>
public static List <T> ToList <T>(this DbDataReader odr, CancellationToken token = default, IDbJobCommand cmd = null)
{
List <T> projectedData = new List <T>();
if (odr.HasRows)
{
Type tType = typeof(T);
if (!DbConnectorUtilities._directTypeMap.Contains(tType) && !(tType.IsValueType && (tType.IsEnum || (Nullable.GetUnderlyingType(tType)?.IsEnum ?? false))) && !tType.IsArray)
{
//Dynamic MSIL cached version is around 30% faster and uses up to 57% less memory.
if (cmd != null && (cmd.Flags & DbJobCommandFlags.NoCache) == DbJobCommandFlags.None)
{
ColumnMapCacheModel cacheModel = new ColumnMapCacheModel(tType, cmd, odr.GetOrdinalColumnNamesHash());
if (!DbConnectorCache.TryGetColumnMap(cacheModel, out IDynamicColumnMapper mapper))
{
mapper = DynamicColumnMapper.CreateMapper <T>(odr.GetOrdinalColumnNames(cmd.MapSettings), cmd.MapSettings);
DbConnectorCache.SetColumnMap(cacheModel, mapper);
}
var genericMapper = mapper as DynamicColumnMapper <T>;
while (odr.Read())
{
if (token.IsCancellationRequested)
{
return(projectedData);
}
projectedData.Add(genericMapper.OnBuild(odr));
}
}
else
{
if (typeof(IEnumerable).IsAssignableFrom(tType))
{
throw new InvalidCastException("The type " + tType + " is not supported");
}
else if (tType.IsClass && tType.GetConstructor(Type.EmptyTypes) == null)
{
throw new InvalidCastException("The type " + tType + " is missing a parameterless constructor");
}
var columnMaps = odr.GetColumnMaps(tType, cmd?.MapSettings);
if (tType.IsClass)
{
while (odr.Read())
{
if (token.IsCancellationRequested)
{
return(projectedData);
}
projectedData.Add(odr.GetMappedObject <T>(columnMaps));
}
}
else
{
while (odr.Read())
{
if (token.IsCancellationRequested)
{
return(projectedData);
}
projectedData.Add((T)odr.GetMappedObject(tType, columnMaps));
}
}
}
}
else if (tType == typeof(Dictionary <string, object>))
{
projectedData = (List <T>)Convert.ChangeType(odr.ToDictionaries(false, token, cmd), typeof(List <Dictionary <string, object> >));
}
else if (tType == typeof(List <KeyValuePair <string, object> >))
{
projectedData = (List <T>)Convert.ChangeType(odr.ToKeyValuePairs(false, token, cmd), typeof(List <List <KeyValuePair <string, object> > >));
}
else if (tType == typeof(DataTable))
{
projectedData.Add((T)Convert.ChangeType(odr.ToDataTable(false, token, cmd.MapSettings), tType));
}
else if (tType == typeof(DataSet))
{
projectedData.Add((T)Convert.ChangeType(odr.ToDataSet(false, token, cmd.MapSettings), tType));
}
else if (tType == typeof(object))
{
projectedData = odr.ToList(token, cmd) as dynamic;
}
else
{
Type nonNullableObjType = tType.IsValueType ? (Nullable.GetUnderlyingType(tType) ?? tType) : tType;
while (odr.Read())
{
if (token.IsCancellationRequested)
{
return(projectedData);
}
object value = odr.GetValue(0);
if (value != DBNull.Value)
{
projectedData.Add((T)(DbConnectorUtilities.ThrowIfFailedToMatchColumnType(tType, nonNullableObjType, value, () => odr.GetName(0))));
}
else
{
projectedData.Add(default);