Log Parser is a great Microsoft tool for processing text-based data. Its scriptable COM components can be easily consumed by .NET applications.
Recently I ran into an interesting error when using the COM components with C#. The data input for the parser is a TSV ((tab-separated values) formatted text log file. Here is code:
LogQueryClassClass logQuery = new LogQueryClassClass();
COMTSVInputContextClassClass inputContext = new COMTSVInputContextClassClass();
inputContext.iCheckpoint = “MyCheckpoint.lpc”;
ILogRecordset recordSet = logQuery.Execute(“SELECT * FROM test.log”, inputContext);
I got all NULL values in the result records or the following exception:
Unhandled Exception: System.Runtime.InteropServices.COMException (0x80094004): Error parsing query: Header for file “test.log” contains an empty field name declaration [Unknown Error]
The weird thing is if I commented out the line which assigns iCheckpoint for incremental parsing, the code would work. Eventually I found out that I needed to specify the CodePage of the inputContext since the text input was encoded in Unicode. So the solution is to add the following line:
inputContext.CodePage = -1; // -1 is Unicode, default (0) is the system codepage