Is there a way to map a property to a custom type in Dapper?

user_544066 0
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We are looking at Dapper to simplify our mapping logic. It looks pretty promising except for one thing. We use custom types for our ids. For example:

public class MyEntityIdentity 
{
    public int IdentityValue { get; }
    public MyEntityIdentity(int identity) { IdentityValue = identity; }
}

public class MyEntity
{
    public MyEntityIdentity Identity { get; set; }
    int Prop1 { get; set; }
    string Prop2 { get; set; }
    bool Prop3 { get; set; }
}

With the SQL table looking something like:

create table [dbo].[MyEntity] (
    my_entity_id int identity(1,1) NOT NULL,
    prop1 int NULL,
    prop2 varchar(100) NULL,
    prop3 bit NOT NULL

    CONSTRAINT PK_MyEntity PRIMARY KEY CLUSTERED (my_entity_id ASC)
)

How can we map the "Identity" property?

dapper c#
1 Answers

You could use custom type handler like this:

public class IdentityHandler : SqlMapper.TypeHandler<MyEntityIdentity>
{
    public override MyEntityIdentity Parse(object value)
    {
        return new MyEntityIdentity((int)value);
    }

    public override void SetValue(IDbDataParameter parameter, MyEntityIdentity value)
    {
        parameter.Value = value.IdentityValue;
    }
}

And register it like this:

SqlMapper.AddTypeHandler(new IdentityHandler());
user_37113320
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