Automapper Projectto unable to create map expression with struct - entity-framework

Question

Isn't there a way to support "wrapped" domain models as structs in mapping when querying using ProjectTo?
For example, I have a struct called Edition, that represents a license edition. In the database, such column is stored as a Integer. However, when consuming a WebApi, such field is returned as a struct Edition. You might ask, if it's a WebApi, just return as int in your model. Well, that's what we are doing under the covers, but we also have a SDK for the api, and in this SDK we modeled the returned class to have the Edition instead of int, so it is clear to the developer what the data means.
We've created .net TypeConverters and Newtonjson converters and all looks good, except AutoMapper throws an exception when using ProjectTo<MyModel>
Unable to create a map expression from ScriptVersion.License (System.Nullable`1[System.Int32]) to ScriptVersionModel.License (System.Nullable`1[Licensing.Edition])
Mapping types:
ScriptVersion -> ScriptVersionModel
Contracts.ScriptVersion -> Api.V10.ScriptVersionModel
Type Map configuration:
ScriptVersion -> ScriptVersionModel
Contracts.ScriptVersion -> Api.V10.ScriptVersionModel
Property:
License
Edition + EditionTypeConverter
[TypeConverter(typeof(EditionTypeConverter))]
[Serializable]
public struct Edition : ISerializable
{
/// <summary>
/// Prefer using <see cref="Edition.Community"/> instead.
/// This only exists to support using <see cref="Edition"/> on <see cref="System.Attribute"/>.
/// </summary>
public const int CommunityNumber = 1024;
/// <summary>
/// Prefer using <see cref="Edition.Standard"/> instead.
/// This only exists to support using <see cref="Edition"/> on <see cref="System.Attribute"/>.
/// </summary>
public const int StandardNumber = 1025;
/// <summary>
/// Prefer using <see cref="Edition.Enterprise"/> instead.
/// This only exists to support using <see cref="Edition"/> on <see cref="System.Attribute"/>.
/// </summary>
public const int EnterpriseNumber = 1026;
public static readonly Edition NotLicensed = new Edition(0);
public static readonly Edition Community = new Edition(CommunityNumber);
public static readonly Edition Standard = new Edition(StandardNumber);
public static readonly Edition Enterprise = new Edition(EnterpriseNumber);
private readonly int edition;
public Edition(int edition)
{
this.edition = edition;
}
public Edition(SerializationInfo info, StreamingContext context)
{
edition = (int)info.GetValue(nameof(edition), typeof(int));
}
public override string ToString()
{
if (edition == NotLicensed)
return "Not Licensed";
if (edition == Community)
return nameof(Community);
if (edition == Standard)
return nameof(Standard);
if (edition == Enterprise)
return nameof(Enterprise);
return $"Unknown({edition})";
}
public override bool Equals(object obj)
{
if (obj == null)
return false;
if (!(obj is Edition))
return false;
var token = (Edition)obj;
return token.edition == edition;
}
public override int GetHashCode() => edition.GetHashCode();
void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue(nameof(edition), edition);
}
public static bool operator !=(Edition left, Edition right) => !(left == right);
public static implicit operator int(Edition edition) => edition.edition;
public static bool operator ==(Edition left, Edition right)
{
if (ReferenceEquals(left, null))
return ReferenceEquals(right, null);
return left.Equals(right);
}
public static Edition? From(int? edition) => edition.HasValue ? new Edition(edition.Value) : (Edition?)null;
public class EditionTypeConverter : TypeConverter
{
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
return sourceType.GetActualType() == typeof(int) ||
sourceType.GetActualType() == typeof(long) ||
base.CanConvertFrom(context, sourceType);
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
if (value == null)
return null;
if (int.TryParse(value.ToString(), out int edition))
return new Edition(edition);
if (long.TryParse(value.ToString(), out long longEdition))
return new Edition((int)longEdition);
return base.ConvertFrom(context, culture, value);
}
}
}
ScriptVersionModel - returned from WebApi
public class ScriptVersionModel
{
public Edition? License{get;set;}
}
ScriptVersion - Entity framework class mapped to database
public class ScriptVersion
{
public int? License{get;set;}
}
code that triggers the error
context.ScriptVersions.Where(predicate).ProjectTo<ScriptVersionModel>();

Answer 1

You can use this
public IMapper InitializeMapper()
{
var configuration = new MapperConfiguration(cfg =>
{
cfg.CreateMap<ScriptVersion, ScriptVersionModel>().ForMember(a => a.License, map => map.MapFrom(src => new Edition(src.License ?? 0)));
});
return configuration.CreateMapper();
}
then
var mapper = InitializeMapper();
ScriptVersionModel edition = mapper.Map<ScriptVersionModel>(new ScriptVersion { License = 12 });
or
context.ScriptVersions.Where(predicate).ProjectTo<ScriptVersionModel>();