private void WriteData <T>(
IEnumerable <T> values,
string fileName,
TextWriter stream,
CsvMetaData metaData)
{
FieldMapper <T> fm = new FieldMapper <T>(metaData, fileName, true);
CsvStream cs = new CsvStream(null, stream, metaData.SeparatorChar, metaData.IgnoreTrailingSeparatorChar);
List <string> row = new List <string>();
// If first line has to carry the field names, write the field names now.
if (metaData.FirstLineHasColumnNames)
{
fm.WriteNames(row);
cs.WriteRow(row, metaData.QuoteAllFields);
}
// -----
foreach (T obj in values)
{
// Convert obj to row
fm.WriteObject(obj, row);
cs.WriteRow(row, metaData.QuoteAllFields);
}
}
public void Write <T>(
IEnumerable <T> values,
TextWriter stream,
CsvMetaData metaData)
{
WriteData(values, null, stream, metaData);
}
/// ///////////////////////////////////////////////////////////////////////
/// FieldMapper
///
/// <summary>
/// Constructor
/// </summary>
/// <param name="metaData"></param>
public FieldMapper_Reading(
CsvMetaData metaData,
string fileName,
bool writingFile)
: base(metaData, fileName, writingFile)
{
}
/// ///////////////////////////////////////////////////////////////////////
/// Read
///
/// <summary>
/// Reads the comma separated values from a stream or file.
/// Returns the data into an IEnumerable<T> that can be used for LINQ queries.
///
/// The stream or file will be closed after the last line has been processed.
/// Because the library implements deferred reading (using Yield Return), this may not happen
/// for a while.
/// </summary>
/// <typeparam name="T">
/// The records in the returned IEnumerable<T> will be of this type.
/// </typeparam>
/// <param name="stream">
/// The data will be read from this stream.
/// </param>
/// <param name="metaData">
/// Additional information how the input file is to be interpreted, such as the culture of the input dates.
/// </param>
/// <returns>
/// Values read from the stream or file.
/// </returns>
public IEnumerable <T> Read <T>(string fileName, CsvMetaData metaData) where T : class, new()
{
// Note that ReadData will not be called right away, but when the returned
// IEnumerable<T> actually gets accessed.
IEnumerable <T> ie = ReadData <T>(fileName, null, metaData);
return(ie);
}
/// ///////////////////////////////////////////////////////////////////////
/// Write
///
public void Write <T>(
IEnumerable <T> values,
string fileName,
CsvMetaData metaData)
{
using (StreamWriter sw = new StreamWriter(
fileName,
false,
metaData.TextEncoding))
{
WriteData(values, fileName, sw, metaData);
}
}
/// ///////////////////////////////////////////////////////////////////////
/// FieldMapper
///
/// <summary>
/// Constructor
/// </summary>
/// <param name="metaData"></param>
public FieldMapper(CsvMetaData metaData, string fileName, bool writingFile)
{
if ((!metaData.FirstLineHasColumnNames) &&
(!metaData.EnforceCsvColumnAttribute))
{
throw new CsvColumnAttributeRequiredException();
}
// ---------
MMetaData = metaData;
m_fileName = fileName;
m_NameToInfo = new Dictionary <string, TypeFieldInfo>();
AnalyzeType(
typeof(T),
!metaData.FirstLineHasColumnNames,
writingFile && !metaData.FirstLineHasColumnNames);
}
/// ///////////////////////////////////////////////////////////////////////
/// ReadData
/// <summary>
///
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="fileName">
/// Name of the file associated with the stream.
///
/// If this is not null, a file is opened with this name.
/// If this is null, the method attempts to read from the passed in stream.
/// </param>
/// <param name="stream">
/// All data is read from this stream, unless fileName is not null.
///
/// This is a StreamReader rather then a TextReader,
/// because we need to be able to seek back to the start of the
/// stream, and you can't do that with a TextReader (or StringReader).
/// </param>
/// <param name="metaData"></param>
/// <returns></returns>
private IEnumerable <T> ReadData <T>(
string fileName,
StreamReader stream,
CsvMetaData metaData) where T : class, new()
{
// If T implements IDataRow, then we're reading raw data rows
bool readingRawDataRows = typeof(IDataRow).IsAssignableFrom(typeof(T));
// The constructor for FieldMapper_Reading will throw an exception if there is something
// wrong with type T. So invoke that constructor before you open the file, because if there
// is an exception, the file will not be closed.
//
// If T implements IDataRow, there is no need for a FieldMapper, because in that case we're returning
// raw data rows.
FieldMapper_Reading <T> fm = null;
if (!readingRawDataRows)
{
fm = new FieldMapper_Reading <T>(metaData, fileName, false);
}
// -------
// Each time the IEnumerable<T> that is returned from this method is
// accessed in a foreach, ReadData is called again (not the original Read overload!)
//
// So, open the file here, or rewind the stream.
bool readingFile = !string.IsNullOrEmpty(fileName);
if (readingFile)
{
stream = new StreamReader(
fileName,
metaData.TextEncoding,
metaData.DetectEncodingFromByteOrderMarks);
}
else
{
// Rewind the stream
if ((stream == null) || (!stream.BaseStream.CanSeek))
{
throw new BadStreamException();
}
stream.BaseStream.Seek(0, SeekOrigin.Begin);
}
// ----------
CsvStream cs = new CsvStream(stream, null, metaData.SeparatorChar, metaData.IgnoreTrailingSeparatorChar);
// If we're reading raw data rows, instantiate a T so we return objects
// of the type specified by the caller.
// Otherwise, instantiate a DataRow, which also implements IDataRow.
IDataRow row = null;
if (readingRawDataRows)
{
row = new T() as IDataRow;
}
else
{
row = new DataRow();
}
AggregatedException ae =
new AggregatedException(typeof(T).ToString(), fileName, metaData.MaximumExceptions);
try
{
List <int> charLengths = null;
if (!readingRawDataRows)
{
charLengths = fm.GetCharLengths();
}
bool firstRow = true;
while (cs.ReadRow(row, charLengths))
{
// Skip empty lines.
// Important. If there is a newline at the end of the last data line, the code
// thinks there is an empty line after that last data line.
if ((row.Count == 1) &&
((row[0].Value == null) ||
(string.IsNullOrEmpty(row[0].Value.Trim()))))
{
continue;
}
if (firstRow && metaData.FirstLineHasColumnNames)
{
if (!readingRawDataRows)
{
fm.ReadNames(row);
}
}
else
{
T obj = default;
try
{
if (readingRawDataRows)
{
obj = row as T;
}
else
{
obj = fm.ReadObject(row, ae);
}
}
catch (AggregatedException ae2)
{
// Seeing that the AggregatedException was thrown, maximum number of exceptions
// must have been reached, so rethrow.
// Catch here, so you don't add an AggregatedException to an AggregatedException
throw ae2;
}
catch (Exception e)
{
// Store the exception in the AggregatedException ae.
// That way, if a file has many errors leading to exceptions,
// you get them all in one go, packaged in a single aggregated exception.
ae.AddException(e);
}
yield return(obj);
}
firstRow = false;
}
}
finally
{
if (readingFile)
{
stream.Close();
}
// If any exceptions were raised while reading the data from the file,
// they will have been stored in the AggregatedException ae.
// In that case, time to throw ae.
ae.ThrowIfExceptionsStored();
}
}
public IEnumerable <T> Read <T>(StreamReader stream, CsvMetaData metaData) where T : class, new()
{
return(ReadData <T>(null, stream, metaData));
}