CsvReader.ColumnCount 始终返回 0，与 CsvReader.Parser.Count 不同

Question

考虑以下代码：

var sb = new StringBuilder();
sb.Append(@"Title,Something");
sb.AppendLine();
sb.Append(@"hello world,abc");
sb.AppendLine();


using var stringReader = new StringReader(sb.ToString());
using var csvReader = new CsvReader(stringReader, CultureInfo.InvariantCulture);

int lineIndex = 0;

while (csvReader.Read())
{
    if (lineIndex == 0)
    {
        csvReader.ReadHeader();
        Debug.WriteLine($"header column count: {csvReader.ColumnCount} and {csvReader.Parser.Count}");
    }
    else
    {
        var foo = csvReader.GetRecord<Foo>();
        Debug.WriteLine($"data column count: {csvReader.ColumnCount} and {csvReader.Parser.Count}");

    }

    lineIndex++;
}

class Foo
{
    public string Title { get; set; } = null!;
    public string Something { get; set; } = null!;
}

输出：

header column count: 0 and 2
data column count: 0 and 2

我对两个零感到困惑，分别

csvReader.ColumnCount

返回0。任何人都可以解释为什么吗？文档指出“这应该与 IParser.Count 匹配”。嗯，应该，但不——但为什么呢？使用最新稳定的 CsvHelper 30.0.1.

Answer 1

目前您必须将

DetectColumnCountChanges = true

设置为

CsvConfiguration

才能从

csvReader.ColumnCount

获得正确的计数。

var sb = new StringBuilder();
sb.AppendLine(@"Title,Something");
sb.AppendLine(@"hello world,abc");

var config = new CsvConfiguration(CultureInfo.InvariantCulture){
    DetectColumnCountChanges = true
};

using var stringReader = new StringReader(sb.ToString());
using var csvReader = new CsvReader(stringReader, config);

int lineIndex = 0;

while (csvReader.Read())
{
    if (lineIndex == 0)
    {
        csvReader.ReadHeader();
        Debug.WriteLine($"header column count: {csvReader.ColumnCount} and {csvReader.Parser.Count}");
    }
    else
    {
        var foo = csvReader.GetRecord<Foo>();
        Debug.WriteLine($"data column count: {csvReader.ColumnCount} and {csvReader.Parser.Count}");

    }

    lineIndex++;
}

class Foo
{
    public string Title { get; set; } = null!;
    public string Something { get; set; } = null!;
}