public static IEnumerable <T> Deserialize <T>(Stream input) where T : new()
{
var result = new List <T>();
IColumnClrMapper mapper = new SlowReflectionColumnClrMapper(typeof(T));
using (var reader = new ParquetReader3(input))
{
Schema fileSchema = reader.Schema;
List <DataField> dataFields = fileSchema.GetDataFields();
for (int i = 0; i < reader.RowGroupCount; i++)
{
using (ParquetRowGroupReader groupReader = reader.OpenRowGroupReader(i))
{
List <DataColumn> groupColumns = dataFields
.Select(groupReader.ReadColumn)
.ToList();
IReadOnlyCollection <T> groupClrObjects = mapper.CreateClassInstances <T>(groupColumns);
result.AddRange(groupClrObjects);
}
}
}
return(result);
}
/// <summary>
/// Extracts data columns from a collection of CLR class instances
/// </summary>
/// <typeparam name="TClass">Class type</typeparam>
/// <param name="classInstances">Collection of class instances</param>
/// <param name="schema">Schema to operate on</param>
public IReadOnlyCollection <DataColumn> ExtractColumns <TClass>(IEnumerable <TClass> classInstances, Schema schema)
{
List <DataField> dataFields = schema.GetDataFields();
IColumnClrMapper valuesExtractor = new SlowReflectionColumnClrMapper(typeof(TClass));
IReadOnlyCollection <DataColumn> result = valuesExtractor.ExtractDataColumns(dataFields, classInstances);
return(result);
}