private IEnumerable <object[]> GetRows(TextFieldParserBuffer parser)
{
for (int i = 0; (!_takeLines.HasValue || i < _takeLines.Value) && !parser.EndOfData; i++)
{
yield return(parser.ReadFields());
}
}
private void Import()
{
var filePath = GetFilePath();
using var stream = File.OpenRead(filePath);
using var bufferedStream = new BufferedStream(stream);
using var parser = NewParser(bufferedStream, _separator.ToString());
var parserBuffer = new TextFieldParserBuffer(parser);
// skip the specified number of initial file lines
for (int i = 0; i < _skipLines && !parserBuffer.EndOfData; i++)
{
parserBuffer.SkipLine();
}
SqlUtil.Import(
ReadColumnNames(parserBuffer),
GetRows(parserBuffer),
_stmt.ImportTable,
_temporaryTable,
_truncateExistingTable,
false, // stopAtFirstBlankRow
_ifConversionFails,
_blankValuesMethod,
_notebook,
_runner,
_env);
}
private List <string> ReadColumnNames(TextFieldParserBuffer parser)
{
var srcColNames = new List <string>();
if (_headerRow)
{
// read the column header row
var cells = parser.ReadFields();
if (cells == null)
{
// end of file; there is nothing here.
if (_skipLines == 0)
{
throw new Exception("No column header row was found because the file is empty.");
}
else
{
throw new Exception("No column header row was found because all rows were skipped.");
}
}
// add a numeric suffix to each column name if necessary to make them all unique
foreach (var cell in cells)
{
var testName = cell;
var testNum = 1;
while (srcColNames.Contains(testName))
{
testNum++;
testName = $"{cell}{testNum}";
}
srcColNames.Add(testName);
}
}
else
{
// no header row so use "column1", "column2", etc. based on the first row of data
var fields = parser.PeekFields();
if (fields == null || !fields.Any())
{
// treat empty file as a single column with no rows
srcColNames.Add("column1");
}
else
{
for (int i = 0; i < fields.Length; i++)
{
srcColNames.Add($"column{i + 1}");
}
}
}
return(srcColNames);
}
private void Import()
{
var filePath = GetFilePath();
using (var stream = File.OpenRead(filePath))
using (var bufferedStream = new BufferedStream(stream))
using (var parser = NewParser(bufferedStream)) {
var parserBuffer = new TextFieldParserBuffer(parser);
// skip the specified number of initial file lines
for (int i = 0; i < _skipLines && !parserBuffer.EndOfData; i++)
{
parserBuffer.SkipLine();
}
// consume the header row if present. invent generic column names if not.
var srcColNames = ReadColumnNames(parserBuffer);
// if the user specified a column list, then check to make sure all of the specified column names exist
// in the list we just read. indices in dstColNodes/dstColNames match up with srcColNames, and some
// elements of dstColNodes may be null if the user does not want to include certain CSV columns.
// all dstColNodes elements will be null if the user specified no columns explicitly, which means they
// want to include all columns.
Ast.ImportColumn[] dstColNodes;
string[] dstColNames;
SqlUtil.GetDestinationColumns(_stmt.ImportTable.ImportColumns, _runner, _env, srcColNames,
out dstColNodes, out dstColNames);
// create or truncate the target table, if necessary.
var dstTableName = _runner.EvaluateIdentifierOrExpr(_stmt.ImportTable.TableName, _env);
SqlUtil.CreateOrTruncateTable(srcColNames, dstColNodes, dstColNames, dstTableName, _temporaryTable,
_truncateExistingTable, _notebook);
// ensure that the target table has all of the requested column names.
SqlUtil.VerifyColumnsExist(dstColNames, dstTableName, _notebook);
// read the data rows and insert into the target table.
SqlUtil.InsertDataRows(GetRows(parserBuffer), dstColNames, dstColNodes, dstTableName, _ifConversionFails,
_notebook);
}
}
