CsvHelper 设置默认自定义 TypeConverter

Question

使用 CsvHelper，当我想要一个自定义解析器时（例如，我想要一个 MyBooleanConverter 并且输入字符串是 "f" 将是 false， "t" 将是 "true"）。但是对于每个 class 我都必须编写映射器：

public sealed class MyClassMap : CsvClassMap<MyClass>
{
    public MyClassMap()
    {
        Map( m => m.Id ).Index( 0 ).TypeConverter<MyBooleanConverter>();
    }
}

或者

[CsvHelper.TypeConversion.TypeConverter( typeof( MyBooleanConverter) )]
public Boolean MyObjectProperty { get; set; }

如何将 MyBooleanConverter 设置为每个布尔字段和每个 Class 的默认值？

Answer 1

CsvHelper 库公开了一个静态 TypeConverterFactory。您可以简单地删除默认的布尔转换器并添加您的自定义转换器来替换它。

TypeConverterFactory.RemoveConverter<bool>();
TypeConverterFactory.AddConverter<bool>(new MyBooleanConverter());

Answer 2

只需将我的代码片段添加到以下 post 即可帮助理解 CsvHelper 中内置的类型转换器。我需要处理以下格式的日期 "yyyyMMdd"，它似乎可以在没有 .net DateTime Parse 错误的情况下来回写入 CSV："String was not recognized as a valid DateTime."

using (TextWriter writer = new StreamWriter(csvLocaitonAndName))
        {
            var csvUpdate = new CsvWriter(writer);
            csvUpdate.Configuration.TypeConverterCache.AddConverter<DateTime?>(new DateConverter("yyyyMMdd"));
            csvUpdate.Configuration.HasHeaderRecord = false;
            csvUpdate.WriteRecords(list);
        }

public class DateConverter : ITypeConverter
    {
        private readonly string _dateFormat;

        public DateConverter(string dateFormat)
        {
            _dateFormat = dateFormat;
        }

        public object ConvertFromString(string text, IReaderRow row, MemberMapData memberMapData)
        {
            if (!string.IsNullOrEmpty(text))
            {
                DateTime dt;
                DateTime.TryParseExact(text, _dateFormat,
                                       CultureInfo.InvariantCulture,
                                       DateTimeStyles.None,
                                       out dt);
                if (IsValidSqlDateTime(dt))
                {
                    return dt;
                }

            }

            return null;
        }
        public string ConvertToString(object value, IWriterRow row, MemberMapData memberMapData)
        {
            return ObjectToDateString(value, _dateFormat);
        }

        public string ObjectToDateString(object o, string dateFormat)
        {
            if (o == null) return string.Empty;

            DateTime dt;
            if (DateTime.TryParse(o.ToString(), out dt))
                return dt.ToString(dateFormat);
            else
                return string.Empty; 
        }
        public bool IsValidSqlDateTime(DateTime? dateTime)
        {
            if (dateTime == null) return true;

            DateTime minValue = DateTime.Parse(System.Data.SqlTypes.SqlDateTime.MinValue.ToString());
            DateTime maxValue = DateTime.Parse(System.Data.SqlTypes.SqlDateTime.MaxValue.ToString());

            if (minValue > dateTime.Value || maxValue < dateTime.Value)
                return false;

            return true;
        }

Answer 3

也可以让 CsvHelper 生成您的 ClassMap，此时您可以为您的成员自定义其处理方式。我发现这对完成我的小爱好项目很有用。

var csv = new CsvReader(streamReader, false);
var classMap = csv.Configuration.AutoMap<Row>(); // ClassMap creation

// My price data has dollar signs so those need to be stripped out before parsing to a decimal
classMap.Map(row => row.Price).ConvertUsing(row => decimal.Parse(row.GetField("Price").Replace("$", "")));

// CsvHelper doesn't support URIs so that requires help as well
classMap.Map(row => row.Source).ConvertUsing(row => new Uri(row.GetField("Source")));

var prices = csv.GetRecords<Row>();



// my DTO
class Row
{
    public decimal Price { get; set; }
    public string ManufacturerSku { get; set; }
    public string Manufacturer { get; set; }
    public Uri Source { get; set; }
    public DateTimeOffset Extraction_Time { get; set; }
}

CsvHelper 设置默认自定义 TypeConverter

CsvHelper set default custom TypeConverter

c#

csvhelper