How can one to dynamically parse a CSV file using C# and the Smart Format Detector in FileHelpers 3.1? - parsing

Question

As per in this FileHelpers 3.1 example, you can automatically detect a CSV file format using the FileHelpers.Detection.SmartFormatDetector class.
But the example goes no further. How do you use this information to dynamically parse a CSV file? It must have something to do with the DelimitedFileEngine but I cannot see how.
Update:
I figured out a possible way but had to resort to using reflection (which does not feel right). Is there another/better way? Maybe using System.Dynamic? Anyway, here is the code I have so far, it ain't pretty but it works:
// follows on from smart detector example
FileHelpers.Detection.RecordFormatInfo lDetectedFormat = formats[0];
Type lDetectedClass = lDetectedFormat.ClassBuilderAsDelimited.CreateRecordClass();
List<FieldInfo> lFieldInfoList = new List<FieldInfo>(lDetectedFormat.ClassBuilderAsDelimited.FieldCount);
foreach (FileHelpers.Dynamic.DelimitedFieldBuilder lField in lDetectedFormat.ClassBuilderAsDelimited.Fields)
lFieldInfoList.Add(lDetectedClass.GetField(lField.FieldName));
FileHelperAsyncEngine lFileEngine = new FileHelperAsyncEngine(lDetectedClass);
int lRecNo = 0;
lFileEngine.BeginReadFile(cReadingsFile);
try
{
while (true)
{
object lRec = lFileEngine.ReadNext();
if (lRec == null)
break;
Trace.WriteLine("Record " + lRecNo);
lFieldInfoList.ForEach(f => Trace.WriteLine(" " + f.Name + " = " + f.GetValue(lRec)));
lRecNo++;
}
}
finally
{
lFileEngine.Close();
}

Answer 1

As I use the SmartFormatDetector to determine the exact format of the incoming Delimited files you can use following appoach:
private DelimitedClassBuilder GetFormat(string file)
{
var detector = new FileHelpers.Detection.SmartFormatDetector();
var format = detector.DetectFileFormat(file);
return format.First().ClassBuilderAsDelimited;
}
private List<T> ConvertFile2Objects<T>(string file, out DelimitedFileEngine engine)
{
var format = GetSeperator(file); // Get Here your FormatInfo
engine = new DelimitedFileEngine(typeof(T)); //define your DelimitdFileEngine
//set some Properties of the engine with what you need
engine.ErrorMode = ErrorMode.SaveAndContinue; //optional
engine.Options.Delimiter = format.Delimiter;
engine.Options.IgnoreFirstLines = format.IgnoreFirstLines;
engine.Options.IgnoreLastLines = format.IgnoreLastLines;
//process
var ret = engine.ReadFileAsList(file);
this.errorCount = engine.ErrorManager.ErrorCount;
var err = engine.ErrorManager.Errors;
engine.ErrorManager.SaveErrors("errors.out");
//return records do here what you need
return ret.Cast<T>().ToList();
}
This is an approach I use in a project, where I only know that I have to process Delimited files of multiple types.
Attention:
I noticed that with the files I recieved the SmartFormatDetector has a problem with tab delimiter. Maybe this should be considered.
Disclaimer: This code is not perfected but in a usable state. Modification and/or refactoring is adviced.