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Merged
merged 1 commit into from
Jul 16, 2025
Merged

Handle invalid message template when skipping parameters array #5933

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29 changes: 26 additions & 3 deletions src/NLog/Logger.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -639,9 +639,7 @@ private void WriteToTargetsWithSpan(ITargetWithFilterChain targetsForLevel, LogL
if (templateEnumerator.MoveNext() && !templateEnumerator.Current.MaybePositionalTemplate)
{
// Convert parameters into Properties and skip Parameters-array-allocation (Like with Microsoft Extension Logging)
var formattedMessage = Factory.AutoMessageTemplateFormatter.Render(ref templateEnumerator, formatProvider, in args, out var messageTemplateParameters);
var logEvent = new LogEventInfo(level, Name, formattedMessage, message, messageTemplateParameters);
logEvent.Exception = exception;
LogEventInfo logEvent = RenderPreformattedLogEvent(Factory.AutoMessageTemplateFormatter, level, exception, formatProvider, message, args, ref templateEnumerator);
WriteLogEventToTargets(logEvent, targetsForLevel);
}
else
Expand All @@ -653,6 +651,31 @@ private void WriteToTargetsWithSpan(ITargetWithFilterChain targetsForLevel, LogL
}
}
}

private LogEventInfo RenderPreformattedLogEvent(LogMessageTemplateFormatter messageTemplateFormatter, LogLevel level, Exception? exception, IFormatProvider? formatProvider, string messageTemplate, in ReadOnlySpan<object?> args, ref MessageTemplates.TemplateEnumerator templateEnumerator)
{
string formattedMessage = messageTemplate;
IList<MessageTemplates.MessageTemplateParameter>? messageTemplateParameters = null;

try
{
formattedMessage = messageTemplateFormatter.Render(ref templateEnumerator, formatProvider, in args, out messageTemplateParameters);
}
catch (Exception ex)
{
Common.InternalLogger.Warn(ex, "Error when formatting a message.");
if (ex.MustBeRethrown())
throw;
}

var logEvent = new LogEventInfo(level, Name, formattedMessage, messageTemplate, (IList<MessageTemplates.MessageTemplateParameter>?)null);
if (messageTemplateParameters is null)
logEvent.Parameters = args.ToArray(); // Failed to parse message-template, so lets captures message-format-parameters
else
logEvent.CreatePropertiesInternal(messageTemplateParameters);
logEvent.Exception = exception;
return logEvent;
}
#endif
#endregion

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10 changes: 8 additions & 2 deletions tests/NLog.UnitTests/LoggerTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2393,9 +2393,15 @@ public void StructuredEventsTest1()
if (enabled == 1) AssertDebugLastMessage("debug", "A|hello from 1=James, 2=Mike, 3=Jane");

logger.Error("message {a} {b}", 1, 2);
if (enabled == 1)
if (enabled == 1) AssertDebugLastMessage("debug", "A|message 1 2");

using (new NoThrowNLogExceptions())
{
AssertDebugLastMessage("debug", "A|message 1 2");
logger.Error("invalid format {age:l}", 30);
if (enabled == 1) AssertDebugLastMessage("debug", "A|invalid format {age:l}");

logger.Error("invalid format {guid:l}", Guid.NewGuid());
if (enabled == 1) AssertDebugLastMessage("debug", "A|invalid format {guid:l}");
}

logger.Error("message{a}{b}{c}", 1, 2, 3);
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