CsvHelper Configuration.ShouldQuote - 仅对 DTO 上的字符串字段返回 true

Question

嗨，有一个DTO对象，其中包含许多不同类型的属性，string，int或bool等。

我只想在string属性周围应用双引号。

在Configuration.ShouldQuote中，field参数值都已转换为string因此无法知道DTO的原始类型是string，int还是bool。

有没有办法从 DTO 找到基础属性类型，以便我只能从 Configuration.ShouldQuote 传回最初属于 string 类型的字段的true？

public class TestDTO
{
    public string Field1 { get; set; }
    public int Field2 { get; set; }
    public bool Field3 { get; set; }
}

    var rawData = new[]
    {
        new TestDTO { Field1 = "Field1", Field2 = 1, Field3 = true },
        new TestDTO { Field1 = "Field2", Field2 = 10, Field3 = false }
    };
    using (var writer = new StreamWriter("file.csv"))
    {
        using (var csv = new CsvWriter(writer))
        {
            csv.Configuration.ShouldQuote = (field, context) =>
            {
                return field is string; // doesn't work as all fields at this point are strings
            };
            csv.WriteRecords(rawData);
        }
    }

Answer 1

CsvHelper 多次更改了ShouldQuote行为，版本 23 再次将此行为从具有多参数委托的行为更改为具有 ShouldQuoteArgs 类型单个参数的行为。

一个非常简单的例子，引用所有非空字符串：

    ...
    var csvConfig = new CsvConfiguration(CultureInfo.InvariantCulture)
    {
        ShouldQuote = args =>
        {
            if (string.IsNullOrEmpty(args.Field)) return false;
            return args.FieldType == typeof(string);
        }
    };

CsvHelper 源中的默认ShouldQuote处理程序是查找更多处理引用方法的好地方。

Answer 2

csv.Configuration.ShouldQuote = (field, context) =>
{
    var index = context.Record.Count;
    var type = ((PropertyInfo)context.WriterConfiguration.Maps.Find<TestDTO>().MemberMaps[index].Data.Member).PropertyType;
    if (type == typeof(string))
    {
        return true;
    }
    return ConfigurationFunctions.ShouldQuote(field, context);
};

您还可以使用自定义转换器。

public class QuoteStringConverter : StringConverter
{
    public override string ConvertToString(object value, IWriterRow row, MemberMapData memberMapData)
    {
        var innerQuotes = ((string)value).Replace(row.Configuration.QuoteString, row.Configuration.DoubleQuoteString);
        var quotedValue = row.Configuration.Quote + innerQuotes + row.Configuration.Quote;
        return base.ConvertToString(quotedValue, row, memberMapData);
    }
}

关闭引号并将转换器添加到TypeConverterCache

var rawData = new[]
{
    new TestDTO { Field1 = "Field1", Field2 = 1, Field3 = true },
    new TestDTO { Field1 = "Field2", Field2 = 10, Field3 = false }
};
using (var writer = new StreamWriter("file.csv"))
using (var csv = new CsvWriter(writer))
{
    csv.Configuration.ShouldQuote = (field, context) => false;
    csv.Configuration.TypeConverterCache.AddConverter<string>(new QuoteStringConverter());
    csv.WriteRecords(rawData);
}