带有 Simple.OData.Client 的 DTO

Question

In my server I have the following setup:

EntitySet<Contact>("Contacts");
EntityType<ContactDto>();

Here's the controller actions:

[EnableQuery]
public ActionResult<IQueryable<ContactDto>> Get()
{
  return Ok(_DbContext.Contacts.Select(c => new ContactDto(c)));
}

[EnableQuery]
public async Task<ActionResult<Contact>> Get(int key)
{
  return await _DbContext.Contacts.FindAsync(key);
}

Contact and ContactDto implement IContact , besides that they are unaware of each other.

When querying the server (using the Contacts route), I get the expected result, but in the client I'm trying to do:

var settings = new ODataClientSettings(new Uri(
    $"https://localhost:{Constants.Port}/{Constants.Api}"));
var client = new ODataClient(settings);

var result = await client
    .For<Contact>()
    .FindEntriesAsync();

And I'm getting an exception:

Microsoft.OData.ODataException: 'The context URL 'https://localhost:54687/api/$metadata#Contacts/ODataDtoRepro.Models.ContactDto' is invalid

StackTrace:

at Microsoft.OData.JsonLight.ODataJsonLightContextUriParser.ParseContextUriFragment(String fragment, Func`3 clientCustomTypeResolver, Boolean throwIfMetadataConflict, Boolean& isUndeclared)
   at Microsoft.OData.JsonLight.ODataJsonLightContextUriParser.ParseContextUri(ODataPayloadKind expectedPayloadKind, Func`3 clientCustomTypeResolver, Boolean throwIfMetadataConflict)
   at Microsoft.OData.JsonLight.ODataJsonLightContextUriParser.Parse(IEdmModel model, String contextUriFromPayload, ODataPayloadKind payloadKind, Func`3 clientCustomTypeResolver, Boolean needParseFragment, Boolean throwIfMetadataConflict)
   at Microsoft.OData.JsonLight.ODataJsonLightDeserializer.ReadPayloadStart(ODataPayloadKind payloadKind, PropertyAndAnnotationCollector propertyAndAnnotationCollector, Boolean isReadingNestedPayload, Boolean allowEmptyPayload)
   at Microsoft.OData.JsonLight.ODataJsonLightReader.ReadAtStartImplementation()
   at Microsoft.OData.ODataReaderCore.ReadImplementation()
   at Microsoft.OData.ODataReaderCore.ReadSynchronously()
   at Microsoft.OData.ODataReaderCore.InterceptException[T](Func`1 action)
   at Microsoft.OData.ODataReaderCore.Read()
   at Simple.OData.Client.V4.Adapter.ResponseReader.ReadResponse(ODataReader odataReader, IODataResponseMessageAsync responseMessage)
   at Simple.OData.Client.V4.Adapter.ResponseReader.<GetResponseAsync>d__3.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
   at Simple.OData.Client.ODataClient.<ExecuteRequestWithResultAsync>d__147`1.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
   at Simple.OData.Client.ODataClient.<FindAnnotatedEntriesAsync>d__88.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
   at Simple.OData.Client.ODataClient.<FindEntriesAsync>d__89.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
   at Simple.OData.Client.FluentClientBase`2.<FilterAndTypeColumnsAsync>d__91.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Client.Program.<Main>d__0.MoveNext() in D:\Users\Shimmy\Documents\Visual Studio 2019\Projects\ODataDtoRepro\Client\Program.cs:line 16

I've made a repro project on GitHub .

I've created another repro branch , that tries a different approach, so that it uses a shared base-class registered in the EDM model, instead of an interface. Still, Simple.OData.Client can't get around it. Please check also my comments on this issue.

How can I get DTOs to work with OData?

Update

Possible solution: using actions/functions. Tried experimenting with it but couldn't make it work between client and server, see this answer for more.

Answer 1

I believe that the issue is that there is no relation between the two objects. I pulled down your code and got it working by removing the entity set

var edmModel = new ODataConventionModelBuilder();
edmModel.EntitySet<ContactDto>("Contacts");
routeBuilder.MapODataServiceRoute("API Route", Constants.Api, edmModel.GetEdmModel());

and by having ContactDto extend Contact

public class ContactDto : Contact

As contact is a subset of contact dto it returns as expected with no errors. Let me know if you want me submit the code to your github.