StrEnum.Dapper

Allows to use StrEnum string enums with Dapper.

Supports Dapper v2.0.4+

Installation

You can install StrEnum.Dapper using the .NET CLI:

dotnet add package StrEnum.Dapper

Usage

Define a string enum and an entity that uses it:

public class Sport: StringEnum<Sport>
{
    public static readonly Sport RoadCycling = Define("ROAD_CYCLING");
    public static readonly Sport MountainBiking = Define("MTB");
    public static readonly Sport TrailRunning = Define("TRAIL_RUNNING");
}

public class Race
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public Sport Sport { get; set; }
}

Initialization

Invoke the StrEnumDapper.UseStringEnums method before the first use of Dapper:

StrEnumDapper.UseStringEnums();

Note, that the UseStringEnums method searches for string enums in all the loaded assemblies, and then registers them with Dapper. Since .NET loads assemblies in a lazy fashion, make sure that the assemblies containing string enums are loaded before calling UseStringEnums. You can do that either implicitly, by referencing types in such assemblies, or by explicitly loading such assemblies. For example, if Sport is located in a separate assembly, you can load it the following way:

Assembly.Load(typeof(Sport).Assembly.GetName());

Executing commands

connection.Execute(@"INSERT Races(Id, Name, Sport) values (@id, @name, @sport)",
    new[]
    {
        new 
        { 
            id = Guid.NewGuid(), 
            name = "Chornohora Sky Marathon", 
            sport = Sport.TrailRunning 
         },
         new 
         { 
             id = Guid.NewGuid(), 
             name = "Cape Town Cycle Tour", 
             sport = Sport.RoadCycling 
          },
          new 
          { 
              id = Guid.NewGuid(), 
              name = "Cape Epic", 
              sport = Sport.MountainBiking 
          }
    });

Running queries

You can pass string enums in query parameters and map them to your entities:

var trailRuns = connection.Query(@"SELECT Id, Name, Sport FROM Races WHERE Sport = @sport", new { sport = Sport.TrailRunning });

Note, that you cannot use string enums in the IN clause - Dapper does not support it yet. The following won't work:

var cyclingRaces = connection.Query(@"SELECT Id, Name, Sport FROM Races WHERE Sport in @sports",
    new { sports = new[]{ Sport.TrailRunning, Sport.MountainBiking }});

The workaround would be to case each of the string enum's members to string:

var cyclingRaces = connection.Query(@"SELECT Id, Name, Sport FROM Races WHERE Sport in @sports",
    new { sports = new[]{ (string)Sport.TrailRunning, (string)Sport.MountainBiking }});

License

Copyright © 2022 Dmitry Khmara.

StrEnum is licensed under the MIT license.