CsvHelper write mapper one property to multiple columns

Question

I'm using csvHelper (version 2.8.4) to write a class to csv. My class looks like this:

public class classA
{
   public int Amount { get; set; }
   public Dictionary<string, string> Dict{ get; set; }
}

Is it possible to write a mapper that maps Dict property to multiple columns? using some sort of converter?

for example if the class has the values:
Amount = 15
Dict = new Dictionary<string,string>{["a1"] = "a2",["b1"] = "b2"}

I want the resulting csv to be:

Amount,a1,b1
15,a2,b2

Thanks!

Answer 1

Possibly the easiest way is going to be to manually write out the dictionary part.

*** Update to work with CsvHelper Version 2.8.4 ***

void Main()
{
    var records = new List<classA>
    {
        new classA {
            Amount = 15,
            Dict = new Dictionary<string,string>{["a1"] = "a2",["b1"] = "b2"}
        }
    };
    
    using (var csv = new CsvWriter(Console.Out))
    {
        var dict = records.First().Dict;

        var properties = typeof(classA).GetProperties();
        
        foreach (PropertyInfo property in properties)
        {
            if (property.Name != "Dict")
            {
                csv.WriteField(property.Name);
            }
        }

        foreach (var item in dict)
        {
            csv.WriteField(item.Key);
        }

        csv.NextRecord();

        foreach (var record in records)
        {
            foreach (PropertyInfo property in properties)
            {
                if (property.Name != "Dict")
                {
                    csv.WriteField(property.GetValue(record));
                }
            }

            foreach (var item in record.Dict)
            {
                csv.WriteField(item.Value);
            }

            csv.NextRecord();
        }
    }
}

// You can define other methods, fields, classes and namespaces here

public class classA
{
    public int Amount { get; set; }
    public Dictionary<string, string> Dict { get; set; }
}

*** Works for current Version 27.2.1 ***

void Main()
{
    var records = new List<classA>
    {
        new classA { Amount = 15, Dict = new Dictionary<string,string>{["a1"] = "a2",["b1"] = "b2"} },
    };

    using (var csv = new CsvWriter(Console.Out, CultureInfo.InvariantCulture))
    {
        var dict = records.First().Dict;
        
        csv.WriteHeader<classA>();
        
        foreach (var item in dict)
        {
            csv.WriteField(item.Key);   
        }
        
        csv.NextRecord();
        
        foreach (var record in records)
        {
            csv.WriteRecord(record);

            foreach (var item in record.Dict)
            {
                csv.WriteField(item.Value);
            }
            
            csv.NextRecord();
        }       
    }
}

public class classA
{
    public int Amount { get; set; }
    public Dictionary<string, string> Dict { get; set; }
}