UseAsDataSource OData expand trows Argument types do not match exception

[mgdmiller]

Hi!

I have simple project that uses odata. I decided to use an automapper because ist very simple. But i have problem with function UseAsDataSource(). When i use ProjectTo() all work fine but EF cannot evaluate filter expressions in db and go it locally. But when i use UseAsDataSource() its throw Argument types do not match exception when specifying $expand. I would like to use the functionality UseAsDataSource() due to performance.

Source/destination types

// DB Objects below

public abstract class BaseDomainObject
{
	[Key]
	public long Id { get; set; }
}

public class Order : BaseDomainObject
{
	public virtual ICollection<OrderPosition> Positions { get;  } = new List<OrderPosition>();
}

public class OrderPosition : BaseDomainObject
{
	public virtual Order Order { get; set; }

	public int Amount { get; set; }
}

// DTO Objects below

public abstract class ApiModel
{
	public long Id { get; set; }
}

public class OrderModel : ApiModel
{
	public IEnumerable<OrderPositionModel> Positions { get; set; }
}

public class OrderPositionModel : ApiModel
{
	public int Amount { get; set; }
}

Mapping configuration

// Profile code

public class OrderProfile : Profile
{
	public OrderProfile()
	{
		CreateMap<BaseDomainObject, ApiModel>();
		CreateMap<Order, OrderModel>().IncludeBase<BaseDomainObject, ApiModel>();
		CreateMap<OrderPosition, OrderPositionModel>().IncludeBase<BaseDomainObject, ApiModel>();
	}
}
	
// Startup code
	
public void ConfigureServices(IServiceCollection services)
{
	services.AddDbContext<OrdersContext>(o =>
	{
		o.UseInMemoryDatabase("test");
		o.UseLazyLoadingProxies();
	});

	services.AddOData();
	services.AddAutoMapper( GetType());
	
	services.AddMvc(options => { options.EnableEndpointRouting = false; }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
}

AutoMapper Version: 9.0.0

EF Version: 2.2.6

Expected behavior

Expected list expansion when specifying $expand=positions

Actual behavior

Throws Argument types do not match

Steps to reproduce

I create demonstration project

Simply call http://localhost:5000/api/orders?$expand=positions

Best regards. Vitaly

[lbargaoanu]

A PR is welcome.

[BlaiseD]

Have you considered the OData Extensions library?

Or creating your own mapping extensions like the ReadMe examples?

[mgdmiller]

Have you considered the OData Extensions library?

Or creating your own mapping extensions like the ReadMe examples?

OData extensions work perfectly! I try to use GetAsync method but it loading all set ignoring PageSize controller option. But GetQueryAsync works as it should.

[EnableQuery]
public async Task<IQueryable<TModel>> Get(ODataQueryOptions<TModel> options)
{
	return await _context.Set<TEntity>().GetQueryAsync(_mapper, options, HandleNullPropagationOption.False);
}

Thank you very much for your help!

[BlaiseD]

Sounds great. Just FYI EnableQuery conflicts with the extension - you could be performing some operations twice. The EnableQuery attribute should be removed. Use $top for page size e.g. http://localhost:1234/controller?$top=5.

[mgdmiller]

Thanks for the clarification! I checked the behavior of EnableQuery, in my conditions it works correctly. The TOP is not a hard limit, which can lead to fetching the entire table. But I will take this into account in the future!

[BlaiseD]

Just so other users get the correct information, do not use the EnableQuery attribute with AutoMapper.Extensions.OData. See the ReadMe documentation and issue #12 at AutoMapper.Extensions.OData. If we're missing a test case, please open an issue at AutoMapper.Extensions.OData.

[mgdmiller]

It is interesting. I publish project to test environment and collect information for explain reply. It will take some time.