Enumeration

This is the feature that enables you to work with enumerations within the class objects. The library supports various kind of transformation for enumerations.

Property String

Let us say you have a table named [dbo].[Person] with the following structure.

CREATE TABLE [dbo].[Person]
(
	[Id] [bigint] IDENTITY(1,1) NOT NULL,
	[Name] [nvarchar](128) NOT NULL,
	[Gender] [nvarchar](16) NOT NULL,
	[CreatedDateUtc] [datetime2](5) NOT NULL,
	CONSTRAINT [CRIX_Person_Id] PRIMARY KEY CLUSTERED ([Id] ASC) ON [PRIMARY]
)
ON [PRIMARY];
GO

Then you can create this enumeration.

public enum Gender
{
    NotDefined,
    Male,
    Female
}

And map it to the Gender column of the Person class.

public class Person
{
	public long Id { get; set; }
	public string Name { get; set; }
	public Gender Gender { get; set; } // Enumeration (As String)
	public DateTime CreatedDateUtc { get; set; }
}

The enumeration values will be saved in the database as String.

Property String (As Int)

You can force the value to be saved as String type if you are using the TypeMap.

public class Person
{
	public long Id { get; set; }
	public string Name { get; set; }
    [TypeMap(DbType.Int32)]
	public Gender Gender { get; set; } // Enumeration (As Forced Int)
	public DateTime CreatedDateUtc { get; set; }
}

Or you can also use the type-level mapping via TypeMapper class.

TypeMapper.Map(typeof(Gender), DbType.Int32);

Property Int

Let us say you have a table named [dbo].[Person] with the following structure.

CREATE TABLE [dbo].[Person]
(
	[Id] [bigint] IDENTITY(1,1) NOT NULL,
	[Name] [nvarchar](128) NOT NULL,
	[Gender] [int] NOT NULL,
	[CreatedDateUtc] [datetime2](5) NOT NULL,
	CONSTRAINT [CRIX_Person_Id] PRIMARY KEY CLUSTERED ([Id] ASC) ON [PRIMARY]
)
ON [PRIMARY];
GO

Then you can create this enumeration.

public enum Gender
{
    NotDefined,
    Male,
    Female
}

And map it to the Gender column of the Person class.

public class Person
{
	public long Id { get; set; }
	public string Name { get; set; }
	public Gender Gender { get; set; } // Enumeration (As Int)
	public DateTime CreatedDateUtc { get; set; }
}

The enumeration values will be saved in the database as Integer.

PropertyHandler

You can as well create a property handler to manually handle the enumerations transformation by implementing the IPropertyHandler.

public class PersonGenderPropertyHandler : IPropertyHandler<Gender?, string>
{
    public Gender? Get(string input, ClassProperty property)
    {
        if (!string.IsNullOrEmpty(input))
        {
            return (Gender)Enum.Parse(typeof(Gender), input);
        }
        return null;
    }
    
    public string Get(Gender? input, ClassProperty property)
    {
        return input?.ToString();
    }
}

And then map it via PropertyHandler.

public class Person
{
    public long Id { get; set; }
    public string Name { get; set; }
    [PropertyHandler(typeof(PersonGenderPropertyHandler))]
    public Gender Gender { get; set; }
    public DateTime CreatedDateUtc { get; set; }
}

The enumeration auto-mapping is being disregard if you have the property handler mapped into the enumeration property. By using the property handler, you have a lot of control as a developer about the transformation.

Query Expression

You can as well use the enumeration in your query expression.

using (var connection = new SqlConnection(connectionString).EnsureOpen())
{
    var females = connection.Query<Person>(e => e.Gender == Gender.Female);
}

Or even in the raw-SQL.

using (var connection = new SqlConnection(connectionString).EnsureOpen())
{
    var females = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE [Gender] = @Gender;", new { Gender = Gender.Female });
}