c# - CsvHealper - 如何忽略 csv 中的空列

Question

csvHelper 的新功能。我想从 csv 文件中删除空列。我正在使用 CsvWriter 将 csv 行定义类写入流。

这是我的代码:

var records = getRecords(); // list of row definition items
var stream = new MemoryStream();
var writer = new StreamWriter(stream);
using (var csv = new CsvWriter(writer))
{
    csv.WriteRecords(records);
    writer.Flush();
    return stream;
}

有没有办法让 CsvWriter 忽略空列？也许配置？

actual csv: 

First Name | Middle Name| Last Name |Gender
FName1     |            | LName1    | Male
FName2     |            | LName2    | Female
FName3     |            | LName3    | 


expected csv:

First Name | Last Name |Gender
FName1     | LName1    | Male
FName2     | LName2    | Female
FName3     | LName3    | 

Answer 1

可以使用配置来实现这一点。

public static void Main(string[] args)
{
    var records = new List<Foo>
    {
        new Foo { FirstName = "FName1", LastName = "LName1", Gender = "Male"},
        new Foo { FirstName = "FName2", LastName = "LName2", Gender = "Female"},
        new Foo { FirstName = "FName3", LastName = "LName3"},
    };

    using (var csv = new CsvWriter(Console.Out))
    {
        var map = new FooMap();

        var properties = typeof(Foo).GetProperties();

        foreach (var property in properties)
        {
            if(records.All(foo => property.GetValue(foo) == null))
            {
                map.Map(typeof(Foo), property).Ignore();
            }
        }

        csv.Configuration.RegisterClassMap(map);

        csv.WriteRecords(records);
    }

    Console.ReadKey();
}

public class Foo
{
    public string FirstName { get; set; }
    public string MiddleName { get; set; }
    public string LastName { get; set; }
    public string Gender { get; set; }
}

public class FooMap : ClassMap<Foo>
{
    public FooMap()
    {
        Map(m => m.FirstName).Name("First Name");
        Map(m => m.MiddleName).Name("Middle Name");
        Map(m => m.LastName).Name("Last Name");
        Map(m => m.Gender);
    }
}

如果您不想创建单独的类映射，只需替换 FooMap与 DefaultClassMap<Foo>并使用 AutoMap .

var map = new DefaultClassMap<Foo>();
map.AutoMap();