Parse string to enum with custom attribute

I have an enum as follows. I also have a string in-progress I am trying to parse this string to the appropriate enum.

The issue being that enum try parse is checking on the name which means its failing. I need to parse it on this custom attribute.

I have been trying to see how I could get a list back of all of the fields within the enum and then test on the literal.

This would work but i have to specify each of the values within the enum in getfield

  var res = typeof(CarePlan.CarePlanActivityStatus)
                 .GetField(nameof(CarePlan.CarePlanActivityStatus.Cancelled))
                 .GetCustomAttribute<EnumLiteralAttribute>(false)
                 .Literal;
            

I tried something like this but Literal doesn’t exist at this point apparently so this fails as well.

  var hold = typeof(CarePlan.CarePlanActivityStatus).GetFields().Where(a =>
            a.GetCustomAttributes<EnumLiteralAttribute>(false).Literal.Equals(data));

The enum

[FhirEnumeration("CarePlanActivityStatus")]
public enum CarePlanActivityStatus
{
  /// <summary>
  /// Care plan activity is planned but no action has yet been taken.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("not-started", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Not Started")] NotStarted,
  /// <summary>
  /// Appointment or other booking has occurred but activity has not yet begun.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("scheduled", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Scheduled")] Scheduled,
  /// <summary>
  /// Care plan activity has been started but is not yet complete.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("in-progress", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("In Progress")] InProgress,
  /// <summary>
  /// Care plan activity was started but has temporarily ceased with an expectation of resumption at a future time.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("on-hold", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("On Hold")] OnHold,
  /// <summary>
  /// Care plan activity has been completed (more or less) as planned.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("completed", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Completed")] Completed,
  /// <summary>
  /// The planned care plan activity has been withdrawn.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("cancelled", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Cancelled")] Cancelled,
  /// <summary>
  /// The planned care plan activity has been ended prior to completion after the activity was started.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("stopped", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Stopped")] Stopped,
  /// <summary>
  /// The current state of the care plan activity is not known.  Note: This concept is not to be used for "other" - one of the listed statuses is presumed to apply, but the authoring/source system does not know which one.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("unknown", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Unknown")] Unknown,
  /// <summary>
  /// Care plan activity was entered in error and voided.
  /// (system: http://hl7.org/fhir/care-plan-activity-status)
  /// </summary>
  [EnumLiteral("entered-in-error", "http://hl7.org/fhir/care-plan-activity-status"), Hl7.Fhir.Utility.Description("Entered in Error")] EnteredInError,
}

// example of everything I have tested with

The nuget package i am using for the fhir library is Hl7.Fhir.R4

public static CarePlan.CarePlanActivityStatus ParseEnum(this string data)
            {
                
                
                // Doesnt work as .Literal shows as red not valid.
                var hold = typeof(CarePlan.CarePlanActivityStatus).GetFields().Where(a =>
                      a.GetCustomAttributes<EnumLiteralAttribute>(false).Literal.Equals(data));
                
                
                // doesnt work as its returning the string i need it to return the enum
                var res = typeof(CarePlan.CarePlanActivityStatus)
                    .GetField(nameof(CarePlan.CarePlanActivityStatus.Cancelled))
                    .GetCustomAttribute<EnumLiteralAttribute>(false)
                    .Literal;
                
                
                

// neither of the following two work as they are just looping though and i cant find the enum they find.
                foreach (CarePlan.CarePlanActivityStatus status in (CarePlan.CarePlanActivityStatus[])Enum.GetValues(
                             typeof(CarePlan.CarePlanActivityStatus)))
                {
                }

                foreach (string i in Enum.GetNames(typeof(CarePlan.CarePlanActivityStatus)))
                {
                    // var res = typeof(CarePlan.CarePlanActivityStatus)
                    //     .GetField(nameof(CarePlan.CarePlanActivityStatus[i]))
                    //     .GetCustomAttribute<EnumLiteralAttribute>(false)
                    //     .Literal;
                    //
                    // Console.WriteLine($" {res}" );  
                    //
                    // Console.WriteLine($" {i}" );  
                }
                
            }

Isnt there a way to parse a string to an enum without making a large mess of a if statements to test it. Ideally i need to create a generic method as i have about 10 of these enums i need test.

>Solution :

You can try with a extension method to read the Custom Atribute from Enums:

public static class EnumExtensions
{
    public static T GetValueFromEnumMember<T>(string value) where T: Enum
    {
        var type = typeof(T);
        foreach (var field in type.GetFields())
        {
            var attribute = Attribute.GetCustomAttribute(field,
                typeof(EnumMemberAttribute)) as EnumMemberAttribute;
            if (attribute != null)
            {
                if (attribute.Value == value)
                    return (T)field.GetValue(null);
            }
            else
            {
                if (field.Name == value)
                    return (T)field.GetValue(null);
            }
        }
        throw new ArgumentException($"unknow value: {value}");
    }
}

and use it like this:

EnumExtensions.GetValueFromEnumMember<CarePlanActivityStatus>(stringValueToTest)

it returns the Enum Value