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Fix CSV columnizer crash when "first line contains field names" is unchecked (#707) #717

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Merged
Hirogen merged 3 commits into from
Sep 26, 2026
Merged

Fix CSV columnizer crash when "first line contains field names" is unchecked (#707) #717

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7688dc8
Fix CSV columnizer crash when first line has no field names (#707)
Hirogen Sep 26, 2026
b3449e3
Fall back to a single Text column when the CSV first line is bad data…
Hirogen Sep 26, 2026
06954ec
Re-detect CSV delimiter on Selected and before the config dialog (#707)
Hirogen Sep 26, 2026
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74 changes: 56 additions & 18 deletions src/CsvColumnizer/CsvColumnizer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -176,35 +176,59 @@ public void Selected (ILogLineMemoryColumnizerCallback callback)
{
ArgumentNullException.ThrowIfNull(callback, nameof(callback));

DetectDelimiterFromFile(callback);
BuildColumns(callback);
}

/// <summary>
/// This instance may not have pre-processed the current file (e.g. a clone that loaded the saved config),
/// so re-detect the delimiter from the file's first line, like PreProcessLine() does on load.
/// </summary>
private void DetectDelimiterFromFile (ILogLineMemoryColumnizerCallback callback)
{
var line = _firstLine ?? callback.GetLogLineMemory(0);
if (line != null)
{
AutoDetectDelimiter(line.FullLine);
}
}

private void BuildColumns (ILogLineMemoryColumnizerCallback callback)
{
if (_isValidCsv) // see PreProcessLine()
{
_columnList.Clear();
var line = _config.HasFieldNames
? _firstLine ?? callback.GetLogLineMemory(0)
: callback.GetLogLineMemory(0);

string[]? fields = null;
if (line != null)
{
using CsvReader csv = new(new StringReader(line.FullLine.ToString()), _config.ReaderConfiguration);
_ = csv.Read();
_ = csv.ReadHeader();

var fieldCount = csv.Parser.Count;

var headerRecord = csv.HeaderRecord;
try
{
fields = ReadFields(line.FullLine.ToString());
}
catch (CsvHelperException)
{
// first line doesn't parse with the current settings (e.g. wrong delimiter); same fallback as SplitCsvLine
}
}

if (_config.HasFieldNames && headerRecord != null)
if (fields != null)
{
if (_config.HasFieldNames)
{
foreach (var headerColumn in headerRecord)
foreach (var headerColumn in fields)
{
_columnList.Add(new CsvColumn(headerColumn));
}
}
else
{
for (var i = 0; i < fieldCount; ++i)
for (var i = 0; i < fields.Length; ++i)
{
_columnList.Add(new CsvColumn("Column " + i + 1));
_columnList.Add(new CsvColumn(string.Format(CultureInfo.InvariantCulture, "Column {0}", i + 1)));
}
}
}
Expand Down Expand Up @@ -254,6 +278,12 @@ public void Configure (ILogLineMemoryColumnizerCallback callback, string configD
var configPath = configDir + "\\" + CONFIGFILENAME;
FileInfo fileInfo = new(configPath);

// show the file's delimiter rather than the one from the saved config
if (callback != null)
{
DetectDelimiterFromFile(callback);
}

CsvColumnizerConfigDlg dlg = new(_config);

if (dlg.ShowDialog() == DialogResult.OK)
Expand All @@ -268,7 +298,11 @@ public void Configure (ILogLineMemoryColumnizerCallback callback, string configD

_config.ConfigureReaderConfiguration();

Selected(callback);
// no re-detection here: keep the delimiter the user chose in the dialog
if (callback != null)
{
BuildColumns(callback);
}
}
}

Expand Down Expand Up @@ -360,6 +394,15 @@ private void AutoDetectDelimiter (ReadOnlyMemory<char> lineContent)
}
}

/// <summary>
/// Parses one line into its fields; avoids ReadHeader(), which throws when HasHeaderRecord is false.
/// </summary>
private string[]? ReadFields (string line)
{
using CsvReader csv = new(new StringReader(line), _config.ReaderConfiguration);
return csv.Read() ? csv.Parser.Record : null;
}

private ColumnizedLogLine SplitCsvLine (ILogLineMemory line)
{
if (line.FullLine.IsEmpty)
Expand All @@ -374,12 +417,7 @@ private ColumnizedLogLine SplitCsvLine (ILogLineMemory line)

try
{
using CsvReader csv = new(new StringReader(line.FullLine.ToString()), _config.ReaderConfiguration);
_ = csv.Read();
_ = csv.ReadHeader();

//we only read line by line and not the whole file so it is always the header
var records = csv.HeaderRecord;
var records = ReadFields(line.FullLine.ToString());

if (records != null)
{
Expand Down
121 changes: 121 additions & 0 deletions src/LogExpert.Tests/ColumnizerTests/CSVColumnizerTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,37 @@ private static void SetPrivateField (CsvColumnizer.CsvColumnizer columnizer, str
field!.SetValue(columnizer, value);
}

private const string HEADERLESS_LINE = "2026-09-01 07:09:58.1980; INFO; 2001:7c0:3006:3014::8602:1a1d; ; ; ; zrnsh01 logged in";

// Valid-CSV mode with "first line contains field names" unchecked
private static CsvColumnizer.CsvColumnizer CreateColumnizerWithoutFieldNames ()
{
CsvColumnizerConfig config = new();
config.InitDefaults();
config.HasFieldNames = false;
config.ConfigureReaderConfiguration();

CsvColumnizer.CsvColumnizer columnizer = new();
SetPrivateField(columnizer, "_config", config);
SetPrivateField(columnizer, "_isValidCsv", true);
return columnizer;
}

// Valid-CSV mode with ',' as configured delimiter, as if loaded from a saved csvcolumnizer.json
private static CsvColumnizer.CsvColumnizer CreateColumnizerWithSavedCommaDelimiter (bool hasFieldNames)
{
CsvColumnizerConfig config = new();
config.InitDefaults();
config.DelimiterChar = ",";
config.HasFieldNames = hasFieldNames;
config.ConfigureReaderConfiguration();

CsvColumnizer.CsvColumnizer columnizer = new();
SetPrivateField(columnizer, "_config", config);
SetPrivateField(columnizer, "_isValidCsv", true);
return columnizer;
}

[Test]
public void Selected_HasFieldNames_FirstLineNull_FallsBackToCallback ()
{
Expand All @@ -81,6 +112,96 @@ public void Selected_HasFieldNames_FirstLineNull_FallsBackToCallback ()
Assert.That(columnizer.GetColumnNames(), Is.EqualTo(["name", "age", "city"]));
}

[Test]
public void Selected_NoFieldNames_ColumnCountFromFirstLine ()
{
var columnizer = CreateColumnizerWithoutFieldNames();
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();
_ = mockCallback.Setup(c => c.GetLogLineMemory(0)).Returns(new CsvLogLine(HEADERLESS_LINE, 0));

columnizer.Selected(mockCallback.Object);

Assert.That(columnizer.GetColumnCount(), Is.EqualTo(7));
}

[Test]
public void Selected_NoFieldNames_GeneratesOneBasedColumnNames ()
{
var columnizer = CreateColumnizerWithoutFieldNames();
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();
_ = mockCallback.Setup(c => c.GetLogLineMemory(0)).Returns(new CsvLogLine(HEADERLESS_LINE, 0));

columnizer.Selected(mockCallback.Object);

Assert.That(columnizer.GetColumnNames(), Is.EqualTo(["Column 1", "Column 2", "Column 3", "Column 4", "Column 5", "Column 6", "Column 7"]));
}

[Test]
public void SplitLine_NoFieldNames_SplitsIntoFields ()
{
var columnizer = CreateColumnizerWithoutFieldNames();
var line = new CsvLogLine(HEADERLESS_LINE, 0);
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();
_ = mockCallback.Setup(c => c.GetLogLineMemory(0)).Returns(line);
columnizer.Selected(mockCallback.Object);

var result = columnizer.SplitLine(mockCallback.Object, line);

Assert.That(result.ColumnValues.Select(c => c.FullValue.ToString()), Is.EqualTo(["2026-09-01 07:09:58.1980", " INFO", " 2001:7c0:3006:3014::8602:1a1d", " ", " ", " ", " zrnsh01 logged in"]));
}

[TestCase(true)]
[TestCase(false)]
public void Selected_FirstLineIsBadData_FallsBackToTextColumn (bool hasFieldNames)
{
var columnizer = CreateColumnizerWithSavedCommaDelimiter(hasFieldNames);
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();
_ = mockCallback.Setup(c => c.GetLogLineMemory(0)).Returns(new CsvLogLine("\"2021-12-12\"x;\"TRACE\"y", 0));

columnizer.Selected(mockCallback.Object);

Assert.That(columnizer.GetColumnNames(), Is.EqualTo(["Text"]));
}

[Test]
public void Selected_NoFieldNames_SavedDelimiterDiffersFromFile_DetectsFileDelimiter ()
{
// Instance that never pre-processed this file, e.g. a clone that loaded ',' from csvcolumnizer.json
var columnizer = CreateColumnizerWithSavedCommaDelimiter(false);
var line = new CsvLogLine("\"2021-12-12\";\"TRACE\";\"semicolon file \"", 0);
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();
_ = mockCallback.Setup(c => c.GetLogLineMemory(0)).Returns(line);

columnizer.Selected(mockCallback.Object);
var result = columnizer.SplitLine(mockCallback.Object, line);

Assert.That(columnizer.GetColumnNames(), Is.EqualTo(["Column 1", "Column 2", "Column 3"]));
Assert.That(result.ColumnValues.Select(c => c.FullValue.ToString()), Is.EqualTo(["2021-12-12", "TRACE", "semicolon file "]));
}

[Test]
public void Selected_HasFieldNames_SavedDelimiterDiffersFromFile_DetectsFileDelimiter ()
{
var columnizer = CreateColumnizerWithSavedCommaDelimiter(true);
SetPrivateField(columnizer, "_firstLine", new CsvLogLine("\"Date\";\"Level\";\"Message\"", 0));
var mockCallback = new Mock<ILogLineMemoryColumnizerCallback>();

columnizer.Selected(mockCallback.Object);

Assert.That(columnizer.GetColumnNames(), Is.EqualTo(["Date", "Level", "Message"]));
}

[Test]
[System.Diagnostics.CodeAnalysis.SuppressMessage("Globalization", "CA1303:Do not pass literals as localized parameters", Justification = "Unit Tests")]
public void PreProcessLine_NoFieldNames_KeepsFirstLineVisible ()
{
var columnizer = CreateColumnizerWithoutFieldNames();

var result = columnizer.PreProcessLine(HEADERLESS_LINE.AsMemory(), 0, 0);

Assert.That(result.ToString(), Is.EqualTo(HEADERLESS_LINE));
}

[Test]
public void Selected_HasFieldNames_NoLineAvailable_FallsBackToTextColumn ()
{
Expand Down
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