filehelpers - 使用相同的类定义将 FixedLength 格式转换为 csv 的问题

Question

我在一个类上同时定义了 FixedLength 和 Delimited 属性。它可以很好地读取固定长度的文件，但是当我尝试写出 csv 时失败。

[FixedLengthRecord]
[DelimitedRecord(",")]
public class PCFFileHeader
{        
    [FieldFixedLength(2)] public string RecordType { get; set; }
    [FieldFixedLength(25)] public string FileDescription { get; set; }
}

var engine = new MultiRecordEngine(typeof(PCFFileHeader), typeof(SecondHeader));

engine.RecordSelector = RecordSelector;
var output = engine.ReadFile(filePath);

// code to extract PCFHeader from output and create a list

var headerEngine = new DelimitedFileEngine<PCFFileHeader>();
headerEngine.WriteFile("header_" + DateTime.Now.ToString("yyyyMMddhhmmss"), pcfFileHeaderList);

Answer 1

您不能将 [FixedLengthRecord] 和 [DelimitedRecord] 添加到同一个类。 FileHelpers 会将其视为 [FixedLengthRecord]。对于您当前的类(class)，如果您这样做，它将出错:

// This causes an exception because the class is not a delimited record definition
var delimitedHeaderEngine = new DelimitedFileEngine<PCFFileHeader>();

相反，您应该有两个 PCFFileHeader 定义，FixedPCFFileHeader 和 DelimitedPCFFileHeader。

[FixedLengthRecord]
public class FixedPCFFileHeader
{
    [FieldFixedLength(2)] public string RecordType { get; set; }
    [FieldFixedLength(25)] public string FileDescription { get; set; }
}

[DelimitedRecord(",")]
public class DelimitedPCFFileHeader
{
    public string RecordType { get; set; }
    public string FileDescription { get; set; }
}


class Program
{
    static void Main(string[] args)
    {
        var fixedHeaderEngine = new FileHelperEngine<FixedPCFFileHeader>();
        var recordsFixed = fixedHeaderEngine.ReadString("AADescription              ");
        Debug.Assert(recordsFixed.Count() == 1);
        Debug.Assert(recordsFixed[0].RecordType == "AA");
        Debug.Assert(recordsFixed[0].FileDescription == "Description              ");

        var delimitedHeaderEngine = new FileHelperEngine<DelimitedPCFFileHeader>();
        var recordsDelimited = delimitedHeaderEngine.ReadString("AA,Description");
        Debug.Assert(recordsDelimited.Count() == 1);
        Debug.Assert(recordsDelimited[0].RecordType == "AA");
        Debug.Assert(recordsDelimited[0].FileDescription == "Description");

        var pcfFileHeaderList = new FixedPCFFileHeader[] { new FixedPCFFileHeader() { RecordType = "AA", FileDescription = "Description" } };
        
        // If you want to output a header when exporting uncomment the following
        //headerEngine.HeaderText = "header_" + DateTime.Now.ToString("yyyyMMddhhmmss");
        
        var output = fixedHeaderEngine.WriteString(pcfFileHeaderList);
        Debug.Assert(output == "AADescription              \r\n");

        Console.WriteLine("All OK");
        Console.ReadLine();
    }
}

如果您想在导入过程中自动检测正确的格式，您可以使用 FileHelpers Smart Format Detector .