I wrote about using SqlBulkCopy to fast load data from .NET into SQL Server database. This class needs a DataTable or IDataReader instance as a source. You can convert a C# List to DataTable (look here Converting List To DataTable). Now I’ll show a couple of examples how to convert List to IDataReader.
1. Straight implementation of IDataReader interface
I’ve seen a couple of good examples from Bruce Dunwiddie https://www.csvreader.com/posts/GenericListDataReader.cs and Venu Gopal http://technico.qnownow.com/custom-data-reader-to-bulk-copy-data-from-object-collection-to-sql-server/. Based on these two solutions I’ve made my one.
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public class ListDataReader<T> : IDataReader where T : class { #region Private fields private IEnumerator<T> _iterator; private List<PropertyInfo> _properties = new List<PropertyInfo>(); #endregion #region Public properties #endregion #region Constructors public ListDataReader(IEnumerable<T> list) { this._iterator = list.GetEnumerator(); _properties.AddRange( typeof(T).GetProperties( BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly ) ); } #endregion #region IDataReader implementation public int Depth { get; } public bool IsClosed { get; } public int RecordsAffected { get; } public void Close() { _iterator.Dispose(); } public DataTable GetSchemaTable() { throw new NotImplementedException(); } public bool NextResult() { throw new NotImplementedException(); } public bool Read() { return _iterator.MoveNext(); } #endregion #region IDisposable implementation public void Dispose() { Close(); } #endregion #region IDataRecord public string GetName(int i) { return _properties[i].Name; } public string GetDataTypeName(int i) { throw new NotImplementedException(); } public Type GetFieldType(int i) { return _properties[i].PropertyType; } public object GetValue(int i) { return _properties[i].GetValue(_iterator.Current, null); } public int GetValues(object[] values) { int numberOfCopiedValues = Math.Max(_properties.Count, values.Length); for (int i = 0; i < numberOfCopiedValues; i++) { values[i] = GetValue(i); } return numberOfCopiedValues; } public int GetOrdinal(string name) { var index = _properties.FindIndex(p => p.Name == name); return index; } public bool GetBoolean(int i) { return (bool) GetValue(i); } public byte GetByte(int i) { return (byte) GetValue(i); } public long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length) { throw new NotImplementedException(); } public char GetChar(int i) { return (char) GetValue(i); } public long GetChars(int i, long fieldoffset, char[] buffer, int bufferoffset, int length) { throw new NotImplementedException(); } public Guid GetGuid(int i) { return (Guid) GetValue(i); } public short GetInt16(int i) { return (short) GetValue(i); } public int GetInt32(int i) { return (int) GetValue(i); } public long GetInt64(int i) { return (long) GetValue(i); } public float GetFloat(int i) { return (float) GetValue(i); } public double GetDouble(int i) { return (double) GetValue(i); } public string GetString(int i) { return (string) GetValue(i); } public decimal GetDecimal(int i) { return (decimal) GetValue(i); } public DateTime GetDateTime(int i) { return (DateTime) GetValue(i); } public IDataReader GetData(int i) { throw new NotImplementedException(); } public bool IsDBNull(int i) { return GetValue(i) == null; } public int FieldCount { get { return _properties.Count; } } object IDataRecord.this[int i] { get { return GetValue(i); } } object IDataRecord.this[string name] { get { return GetValue(GetOrdinal(name)); } } #endregion } |
Now you can iterate through IDataReader like you do with SqlDataReader.
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using (IDataReader reader = new ListDataReader<Client>(clients)) { while (reader.Read()) { ... } } |
2. FastMember NuGet package
Thank you, Marc! it’s a good job https://github.com/mgravell/fast-member
You need to install NuGet package FastMember, add using FastMember; statement, and run this code.
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using (var reader = ObjectReader.Create(clients)) { while (reader.Read()) { ... } } |