Fluxera.Enumeration.EntityFrameworkCore 6.0.3

Fluxera.Enumeration

An object-oriented enumeration library.

Usage

Define an enumerable as C# class that inherits from the Enumeration<TEnum> base class. Add the enumeration options as public static readonly fields to the new enumerable class.

public sealed class Color : Enumeration<Color>
{
    public static readonly Color Red = new Color(0, "FF0000");
    public static readonly Color Green = new Color(1, "00FF00");
    public static readonly Color Blue = new Color(2, "0000FF");
    public static readonly Color White = new Color(3, "FFFFFF");
    public static readonly Color Black = new Color(4, "000000");

    /// <inheritdoc />
    private Color(int value, string hexValue, [CallerMemberName] string name = null!) 
        : base(value, name)
    {
        this.HexValue = hexValue;
    }

    public string HexValue { get; }
}

public class MessageType : Enumeration<MessageType>
{
    public static readonly MessageType Email = new EmailType();
    public static readonly MessageType Postal = new PostalType();
    public static readonly MessageType TextMessage  = new TextMessageType();

    /// <inheritdoc />
    private MessageType(int value, string name) 
        : base(value, name)
    {
    }

    private sealed class EmailType : MessageType
    {
        /// <inheritdoc />
        public EmailType() : base(0, "Email")
        {
        }
    }

    private sealed class PostalType : MessageType
    {
        /// <inheritdoc />
        public PostalType() : base(1, "Postal")
        {
        }
    }

    private sealed class TextMessageType : MessageType
    {
        /// <inheritdoc />
        public TextMessageType() : base(2, "TextMessage")
        {
        }
    }
}

public abstract class Animal : Enumeration<Animal>
{
    /// <inheritdoc />
    protected Animal(int value, string name) 
        : base(value, name)
    {
    }
}

public sealed class Mammal : Animal
{
    public static readonly Mammal Tiger = new Mammal(0);
    public static readonly Mammal Elephant = new Mammal(1);

    /// <inheritdoc />
    private Mammal(int value, [CallerMemberName] string name = null!) 
        : base(value, name)
    {
    }
}

public sealed class Reptile : Animal
{
    public static readonly Reptile Iguana = new Reptile(2);
    public static readonly Reptile Python = new Reptile(3);

    /// <inheritdoc />
    private Reptile(int value, [CallerMemberName] string name = null!) 
        : base(value, name)
    {
    }
}

The Enumeration<TEnum> provides a fluent API to configure switch-case like structures to simplify the execution of action for specific cases.

public void PrintColorInfo(Color color)
{
    color
        .When(Color.Red).Then(() => SetConsoleColor(ConsoleColor.Red))
        .When(Color.Blue).Then(() => SetConsoleColor(ConsoleColor.Blue))
        .When(Color.Green).Then(() => SetConsoleColor(ConsoleColor.Green))
        .Default(() => SetConsoleColor(ConsoleColor.White));

    Console.WriteLine($"{color}({color.Value}) => #{color.HexValue}");
}

Future

We plan to implement support for OData server- and client-side to enable queries on Enumeration like is was an simple C# enum. An Enumeration should generate an EdmEnumType in the metadata for an OData feed.

The simple way would be to add the enumeraions as complex type, but that feels wrong because the object-oriented enumeration should work like an enum and the EDM model would not reflect the available options.

EdmEnumType color = new EdmEnumType("Default", "Color");
color.AddMember(new EdmEnumMember(color, "Red", new EdmIntegerConstant(0)));
color.AddMember(new EdmEnumMember(color, "Blue", new EdmIntegerConstant(1)));
color.AddMember(new EdmEnumMember(color, "Green", new EdmIntegerConstant(2)));
model.AddElement(color);

This cannot be achieved using the model builder because the enum methods are tightly bound to C# enum.

<EnumType Name="Color">
   <Member Name="Red" Value="0" />
   <Member Name="Blue" Value="1" />
   <Member Name="Green" Value="2" />
</EnumType>

We want to support filter queries like so:

https://localhost:5001/odata/Cars?$filter=Color eq 'Blue'
https://localhost:5001/odata/Cars?$filter=Color eq 1

https://github.com/OData/WebApi/issues/1186 https://github.com/OData/WebApi/blob/master/src/Microsoft.AspNet.OData.Shared/UnqualifiedCallAndEnumPrefixFreeResolver.cs

We also plan to support Swagger documentation in ASP.NET Core applications.

References

This library was inspired by:

Søren Pedersen - Enumeration

Steve Smith - SmartEnum

Kyle Herzog - ExtendableEnums

MakoLab S.A. - SpecializedEnum