Seekatar.OptionToStringGenerator 0.1.4

OptionToString Incremental Source Generator

Problem: I have configuration class for use with IOptions and I want to safely log out its values at runtime.

Solution: Use an incremental source generator to generate an extension method to get a string with masked values for the properties.

This package generates an OptionToString extension method for your classes. By marking properties in the class you can control how the values are masked. It was created for dumping out objects used by IOptions or IConfiguration when the application starts.

Usage

1. Add the OptionToString NuGet package to your project.
2. Decorate a class with the OptionToStringAttribute attribute.
3. Optionally decorate properties with how you want them to be you want to dump out. If you don't decorate a property, its full text is dumped out.

Example

Here's an example class of the various options with values set in the class for illustration purposes. The output follows.

namespace Test;
using Seekatar.OptionToStringGenerator;

[OptionsToString]
public class PublicOptions
{
    public class AClass
    {
        public string Name { get; set; } = "maybe this is secret";
        public override string ToString() => $"{nameof(AClass)}: {Name}";
    }

    public string PlainText { get; set; } = "hi mom";

    public int PlainNumber { get; set; } = 42;

    public DateTime PlainDateTime { get; set; } = new DateTime(2020, 1, 1);

    public string? NullItem { get; set; }

    public AClass AnObject { get; set; } = new();

    [OutputRegex(Regex = @"AClass\:\s+(.*)")]
    public AClass AMaskedObject { get; set; } = new();

    [OutputMask]
    public string FullyMasked { get; set; } = "thisisasecret";

    [OutputMask(PrefixLen=3)]
    public string FirstThreeNotMasked { get; set; } = "abc1233435667";

    [OutputMask(PrefixLen = 100)]
    public string NotMaskedSinceLongLength { get; set; } = "abc1233435667";

    [OutputLengthOnly]
    public string LengthOnly { get; set; } = "thisisasecretthatonlyshowsthelength";

    [OutputRegex(Regex="User Id=([^;]+).*Password=([^;]+)")]
    public string MaskUserAndPassword { get; set; } = "...;User Id=myUsername;Password=myPassword;";

    [OutputRegex(Regex="User Id=([^;]+).*Password=([^;]+)",IgnoreCase=true)]
    public string MaskUserAndPasswordIngoreCase { get; set; } = "...;user Id=myUsername;Password=myPassword;";

    [OutputRegex(Regex = "User Id=([^;]+).*Password=([^;]+)")]
    public string RegexNotMatched { get; set; } = "...;user Id=myUsername;Password=myPassword;";

    [OutputIgnore]
    public string IgnoreMe { get; set; } = "abc1233435667";
}
// usage
var options = new PublicOptions();
_logger.LogInformation(options.OptionToString());

The output has the class name followed by an indented list of all the properties' values masked as specified.

integration.PublicOptions:
  PlainText                     : "hi mom"
  PlainNumber                   : 42
  PlainDateTime                 : 1/1/2020 12:00:00 AM
  NullItem                      : null
  AnObject                      : AClass: maybe this is secret
  AMaskedObject                 : AClass: ***
  FullyMasked                   : "*************"
  FirstThreeNotMasked           : "abc**********"
  NotMaskedSinceLongLength      : "abc1233435667"
  LengthOnly                    : Len = 35
  MaskUserAndPassword           : ...;User Id=***;Password=***;
  MaskUserAndPasswordIngoreCase : ...;user Id=***;Password=***;
  RegexNotMatched               : ***!

Notes

• All public properties are included by default and output as plain text.
• Use the OutputIgnore attribute to exclude a property.
• ToString() is called on the property's value, then the mask is applied. You can have a custom ToString() method on a class to format its output then it will be masked as the AClass example above.
• Only one Output* attribute is allowed per property. If more than one is set, you'll get a compile warning, and the last attribute set will be used.
• Regex strings with back slashes need to use a verbatim string or escape the back slashes (e.g. @"\s+" or "\\s+").
• OutputRegex must have a Regex parameter, or you'll get a compile error.
• If the regex doesn't match the value, the output will be ***! to indicate it didn't match.