Leniently Parse Comma Separated Configuration Values Using C#

Whether you’re using .NET you may want to read configuration values at runtime. Sometimes the value might look like "a,b,c", which some might write as "a, b, c". When configuration values are comma separated or delimited in some manner it’s a good idea to be forgiving when reading the input.

.NET 5 and later

var values = stringValue
  ?.Split(",", StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
  ?? Array.Empty<string>();

Extension methods:

public static class StringExtensions
{
    public static IEnumerable<string> LenientlyParseDelimited(this string str)
    {
        return LenientlyParseDelimited(str, new[] { "," });
    }

    public static IEnumerable<string> LenientlyParseDelimited(this string str, params string[] delimiters)
    {
        if (delimiters == null) throw new ArgumentNullException(nameof(delimiters));

        return str
            ?.Split(delimiters, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
            ?? Array.Empty<string>();
    }
}

Earlier .NET versions

var values = stringValue
    ?.Split(new[] { "," }, StringSplitOptions.RemoveEmptyEntries)
    .Select(x => x?.Trim())
    .Where(x => !string.IsNullOrWhiteSpace(x))
    ?? Array.Empty<string>();

Extension methods:

public static class StringExtensions
{
    public static IEnumerable<string> LenientlyParseDelimited(this string str)
    {
        return LenientlyParseDelimited(str, new[] { "," });
    }

    public static IEnumerable<string> LenientlyParseDelimited(this string str, params string[] delimiters)
    {
        if (delimiters == null) throw new ArgumentNullException(nameof(delimiters));

        return str
            ?.Split(delimiters, StringSplitOptions.RemoveEmptyEntries)
            .Select(x => x?.Trim())
            .Where(x => !string.IsNullOrWhiteSpace(x))
            ?? Array.Empty<string>();
    }
}

This approach parses the input leniently by removing empty and whitespace only entries while trimming whitespace on each split value. This can be helpful since an unexpected space character could cause an issue. You could even add additional delimiters like ';' to the array.

Configuration problems can be a frustrating source of deployment issues. Leninently parsing delimited strings might just save you from a production issue.