C#•4w ago

My class needs property type which can only either be string or int -not sure how to best implement

Working on a project to make a simple IT monitoring system - just for fun. I have a INormalisedDataPoint - this represents the interface for ingested Log/Metric data which has been processed and normalised. It has a property called Messages, where I intend to store a List<IMessageField> - so Messages would include things like CPU%: 95%, dataSource: my-macbook, ipAddress: ..... and so on. I will be ingesting both logs and metrics (numeric values).
Possible solutions I can think of: 1. I could just make IMessageField have a string Name and string Value , and then convert the string to a numeric type, but I'd like to figure out how to accept either type, as a learning experience. 2. I could have a NumericMessageField (which stores a number) and a StringMessageField which stores a string.

7 Replies

cm17OP•4w ago

Here's my code so far:

public interface INormalisedDataPoint
{
    public Guid Id { get; set; }
    public DateTime Timestamp { get; init; }
    public List<IMessageField> MessageFields { get; set; }
    public string Source { get; set; }
}

public interface IMessageField
{
    public string Name { get; set; }
    // THERE SHOULD BE A 'Value' Property here too but I had to put that in the MessageField<T> class to make it work...

}

public class ValueField<T>
{
    public T Value { get; set; }
}

public class MessageField<T> : IMessageField
{
    public string Name { get; set; } = "";
    public ValueField<T> Value { get; set; } = new ValueField<T>(); // THIS MUST BE EITHER A DOUBLE OR STRING

}

public class DataPoint
{
    public Guid Id { get; set; }
    public List<IMessageField> MessageFields { get; set; }


    public DataPoint()
    {
        Id = Guid.NewGuid();

        // INITIALISING WITH DUMMY DATA FOR TESTING PURPOSES
        MessageFields = new() {
            new MessageField<string> { Name = "source", Value = new ValueField<string> { Value = "my-macbook" } },
            new MessageField<int> { Name = "CPU%", Value = new ValueField<int> { Value = 10 } }
            };
    }
}

public interface INormalisedDataPoint
{
    public Guid Id { get; set; }
    public DateTime Timestamp { get; init; }
    public List<IMessageField> MessageFields { get; set; }
    public string Source { get; set; }
}

public interface IMessageField
{
    public string Name { get; set; }
    // THERE SHOULD BE A 'Value' Property here too but I had to put that in the MessageField<T> class to make it work...

}

public class ValueField<T>
{
    public T Value { get; set; }
}

public class MessageField<T> : IMessageField
{
    public string Name { get; set; } = "";
    public ValueField<T> Value { get; set; } = new ValueField<T>(); // THIS MUST BE EITHER A DOUBLE OR STRING

}

public class DataPoint
{
    public Guid Id { get; set; }
    public List<IMessageField> MessageFields { get; set; }


    public DataPoint()
    {
        Id = Guid.NewGuid();

        // INITIALISING WITH DUMMY DATA FOR TESTING PURPOSES
        MessageFields = new() {
            new MessageField<string> { Name = "source", Value = new ValueField<string> { Value = "my-macbook" } },
            new MessageField<int> { Name = "CPU%", Value = new ValueField<int> { Value = 10 } }
            };
    }
}

mtreit•4w ago

What you are describing is what's called a Discriminated Union. Some languages like F# support this, but C# unfortunately does not currently have this.

mtreit•4w ago

There is a NuGet package that allows you to emulate this: https://www.nuget.org/packages/OneOf

OneOf 3.0.271

F# style discriminated unions for C#, using a custom type OneOf<T0, ... Tn> which holds a single value and has a .Match(...) method on it for exhaustive matching. Simple but powerful.

mtreit•4w ago

I have not used it however.

Pobiega•4w ago

I'd probably use an abstract record MessageField and record StringMessageField(string Value) : MessageField;, assuming you need to serialize/deserialize this then slap on some [JsonDerivedType] and be happy

Kuurama•4w ago

public interface INormalisedDataPoint
{
    public Guid Id { get; set; }
    public DateTime Timestamp { get; init; }
    public List<MessageField> MessageFields { get; set; }
    public string Source { get; set; }
}

public static class MessageFieldExtensions
{
    public static void Print(this MessageField self)
    {
        switch (self)
        {
            case MessageField.StringMessageField(var name, var value):
                Console.WriteLine($"String Field - Name: {name}, Value: {value}");
                break;
            case MessageField.DoubleMessageField (var name, var value):
                Console.WriteLine($"Double Field - Name: {name}, Value: {value}");
                break;
        }
    }
}

public abstract record MessageField(string Name)
{
    public sealed record StringMessageField(string Name, string Value) : MessageField(Name);
    public sealed record DoubleMessageField(string Name, double Value) : MessageField(Name);
}

public class DataPoint
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public List<MessageField> MessageFields { get; set; } =
    [
        new MessageField.StringMessageField("source", "my-macbook"),
        new MessageField.DoubleMessageField("CPU%", 10)
    ];
}

public interface INormalisedDataPoint
{
    public Guid Id { get; set; }
    public DateTime Timestamp { get; init; }
    public List<MessageField> MessageFields { get; set; }
    public string Source { get; set; }
}

public static class MessageFieldExtensions
{
    public static void Print(this MessageField self)
    {
        switch (self)
        {
            case MessageField.StringMessageField(var name, var value):
                Console.WriteLine($"String Field - Name: {name}, Value: {value}");
                break;
            case MessageField.DoubleMessageField (var name, var value):
                Console.WriteLine($"Double Field - Name: {name}, Value: {value}");
                break;
        }
    }
}

public abstract record MessageField(string Name)
{
    public sealed record StringMessageField(string Name, string Value) : MessageField(Name);
    public sealed record DoubleMessageField(string Name, double Value) : MessageField(Name);
}

public class DataPoint
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public List<MessageField> MessageFields { get; set; } =
    [
        new MessageField.StringMessageField("source", "my-macbook"),
        new MessageField.DoubleMessageField("CPU%", 10)
    ];
}

You don't have to put them into MessageField, or you can also using static MessageField; at the top of the file. using static FooCurrentNameSpace.MessageField; or

public abstract record MessageField(string Name);
public sealed record StringMessageField(string Name, string Value) : MessageField(Name);
public sealed record DoubleMessageField(string Name, double Value) : MessageField(Name);

public class DataPoint
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public List<MessageField> MessageFields { get; set; } =
    [
        new StringMessageField("source", "my-macbook"),
        new DoubleMessageField("CPU%", 10)
    ];
}

public abstract record MessageField(string Name);
public sealed record StringMessageField(string Name, string Value) : MessageField(Name);
public sealed record DoubleMessageField(string Name, double Value) : MessageField(Name);

public class DataPoint
{
    public Guid Id { get; set; } = Guid.NewGuid();

    public List<MessageField> MessageFields { get; set; } =
    [
        new StringMessageField("source", "my-macbook"),
        new DoubleMessageField("CPU%", 10)
    ];
}

Then you can write switch expression and switch statements depending on the case. I miss the point of INormalisedDataPoint though. But I still included it.

cm17OP•2w ago

Thanks for your help everyone

Gaming

Programming

My class needs property type which can only either be string or int -not sure how to best implement

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