Migrating to v11.0.0

CsvHelper 11 replaces the writer's quoting switches, QuoteAllFields, QuoteNoFields, QuoteRequiredChars and BuildRequiredQuoteChars, with one function, ShouldQuote, that decides for each field whether to quote it. Only writing is affected: reading, mapping and the target frameworks (.NET Standard 2.0 and .NET Framework 4.5) are the same.

Quoting fields

ShouldQuote gets the field and the writing context, and returns true to quote the field. The two switches become functions that always answer the same:

using var csv = new CsvWriter(writer);
csv.Configuration.QuoteAllFields = true;
csv.WriteField("Widget");
csv.NextRecord();

using var csv = new CsvWriter(writer);
csv.Configuration.ShouldQuote = (field, context) => true;
csv.WriteField("Widget");
csv.NextRecord();

The default, ConfigurationFunctions.ShouldQuote, quotes a field that contains a quote, \r, \n or the delimiter, or that starts or ends with a space. To add a rule, call it from your function:

using var csv = new CsvWriter(writer);
csv.Configuration.ShouldQuote = (field, context) =>
    ConfigurationFunctions.ShouldQuote(field, context) || (field != null && field.Contains("\t"));

• The field can be null: WriteField((string)null) passes it to the function as it is.
• Trimming comes first: with TrimOptions.Trim, the function gets the trimmed field.
• WriteField(field, shouldQuote) still quotes as you tell it, without calling the function.

Behavior changes

With AllowComments, 10 quoted the first field of a record when it started with the Comment character, so that the record wasn't read back as a comment. The default ShouldQuote doesn't do that. If you write files with comments, add the rule:

using var csv = new CsvWriter(writer);
csv.Configuration.AllowComments = true;
csv.Configuration.ShouldQuote = (field, context) =>
    ConfigurationFunctions.ShouldQuote(field, context)
    || (context.WriterConfiguration.AllowComments
        && context.Record.Count == 0
        && !string.IsNullOrEmpty(field)
        && field[0] == context.WriterConfiguration.Comment);