Writing a collection that contains collections

[CallMeBruce]

Hi, is it possible to write a collection that contains collections, e.g. parent record, and child records?

--> Parent1, Name, Age
-->--> Child1, Field1, Field2
-->--> Child2, Field1, Field2
--> Parent2, Name, Age
-->--> Child3, Field1, Field2
...

I thought that the AutoMapper might do this via it's recursion, however when I tried it using WriteRecords(items) however only the parent record was written.

Thanks

[jamesbascle]

You cannot have nested collections as far as I know. You CAN have nested objects however. See reference maps just under the AutoMapping section @ http://joshclose.github.io/CsvHelper/

[JoshClose]

Enumerable properties are supported in version 3.0.

[Jerome2606]

Can you provide example to add row for each nested object ? (I'm ok to use version 3.0 but how ?)

[JoshClose]

void Main()
{
	using (var stream = new MemoryStream())
	using (var writer = new StreamWriter(stream))
	using (var reader = new StreamReader(stream))
	using (var csv = new CsvReader(reader))
	{
		writer.WriteLine("Id,Name,A,B,C");
		writer.WriteLine("1,one,a,b,c");
		writer.WriteLine("2,two,d,e,c");
		writer.Flush();
		stream.Position = 0;
		
		csv.Configuration.RegisterClassMap<TestMap>();
		csv.GetRecords<Test>().ToList().Dump();
	}
}

public class Test
{
	public int Id { get; set; }
	public string Name { get; set; }
	public List<string> ExtraStrings { get; set; }
}

public sealed class TestMap : CsvClassMap<Test>
{
	public TestMap()
	{
		Map( m => m.Id );
		Map( m => m.Name );
		Map( m => m.ExtraStrings ).Index( 2 );
	}
}

You can also take a look at the unit tests if you like. https://github.com/JoshClose/CsvHelper/tree/master/src/CsvHelper.Tests/TypeConversion

[jzabroski]

Updated working example for 19.0.0 👍

void Main()
{
	using (var stream = new MemoryStream())
	using (var writer = new StreamWriter(stream))
	using (var reader = new StreamReader(stream))
	using (var csv = new CsvReader(reader, System.Globalization.CultureInfo.CurrentCulture))
	{
		writer.WriteLine("Id,Name,A,B,C");
		writer.WriteLine("1,one,a,b,c");
		writer.WriteLine("2,two,d,e,c");
		writer.Flush();
		stream.Position = 0;

		csv.Configuration.RegisterClassMap<TestMap>();
		csv.GetRecords<Test>().ToList().Dump();
	}
}

public class Test
{
	public int Id { get; set; }
	public string Name { get; set; }
	public List<string> ExtraStrings { get; set; }
}

public sealed class TestMap : ClassMap<Test>
{
	public TestMap()
	{
		Map(m => m.Id);
		Map(m => m.Name);
		Map(m => m.ExtraStrings).Index(2);
	}
}