How to map GUID to BLOB in EF Core SQLite

Hello there!

EF Core changed the way how GUIDs are stored in the SQLite database. Starting from version 3.0, they are stored as TEXT GitHub. But what is you want to change it back. Then you need to introduce a value converter to convert GUIDs to byte arrays.

public static class ModelBuilderExtensions
{
    public static void ConfigureGuids(this ModelBuilder modelBuilder)
    {
        foreach (var entity in modelBuilder.Model.GetEntityTypes())
        {
            var properties = entity.GetProperties().Where(x => x.ClrType == typeof(Guid));
 
            foreach (var property in properties)
            {
                property.SetColumnType("BLOB");
                property.SetValueConverter(GuidConverter.Instance);
            }
 
            properties = entity.GetProperties().Where(x => x.ClrType == typeof(Guid?));
 
            foreach (var property in properties)
            {
                property.SetColumnType("BLOB");
                property.SetValueConverter(NullableGuidConverter.Instance);
            }
        }
    }
}
 
public class GuidConverter : ValueConverter<Guid, byte[]>
{
    public static readonly GuidConverter Instance = new GuidConverter();
 
    public GuidConverter()
        : base(x => x.ToByteArray(), x => new Guid(x))
    {
    }
}
 
public class NullableGuidConverter : ValueConverter<Guid?, byte[]?>
{
    public static readonly NullableGuidConverter Instance = new NullableGuidConverter();
 
    public NullableGuidConverter()
        : base(
            x => x != null ? x.Value.ToByteArray() : null,
            x => x != null ? new Guid(x) : null)
    {
    }
}

Here is an extension method to use in OnModelCreating of DbContext. It scans all properties with Guid or Guid? types, sets their column types as BLOB, and registers converters.