Migrating to v16.0.0

CsvHelper 16 adds GetDynamicPropertyName, a setting that names the properties of the records GetRecords<dynamic>() returns. With it you can read a file whose header has the same name twice, which failed before, since both columns got the same property name. The names stay the same unless you set it. Code that implements IReaderConfiguration needs the new property.

Dynamic record property names

In 15, a dynamic record's property names were the header names passed through PrepareHeaderForMatch, so making them unique meant changing how every header is matched, for class records too. In 16, GetDynamicPropertyName names them, and changes only dynamic records:

var config = new CsvConfiguration(CultureInfo.InvariantCulture)
{
    PrepareHeaderForMatch = (header, index) => header + index,
};
using var csv = new CsvReader(reader, config);
var records = csv.GetRecords<dynamic>().ToList();
// Name,Name,Age gives Name0, Name1 and Age2

var config = new CsvConfiguration(CultureInfo.InvariantCulture)
{
    GetDynamicPropertyName = (context, index) =>
    {
        var header = context.HeaderRecord[index];
        var count = context.HeaderRecord.Take(index).Count(h => h == header);

        return count == 0 ? header : header + (count + 1);
    },
};
using var csv = new CsvReader(reader, config);
var records = csv.GetRecords<dynamic>().ToList();
// Name,Name,Age gives Name, Name2 and Age

• The default is ConfigurationFunctions.GetDynamicPropertyName, which names them as 15 did: the header name passed through PrepareHeaderForMatch, or Field1, Field2 and so on when there is no header.
• Without a header, context.HeaderRecord is null: the function above is for files with one.