OData API versioning issue .net core 3.1

Question

I received an application startup exception, related to the OData API versioning. The exception message:

The entity model (EDM) does not have the required ApiVersionAnnotation annotation

The snippet of mapping versioned odata route

 public static IEndpointRouteBuilder MapPaymentsODataRoute(this IEndpointRouteBuilder builder)
    {
        builder.MapVersionedODataRoute(
            "payments-odata",
            "api/v{apiVersion:apiVersion}/payment-service/odata",
            new List<IEdmModel> { BuildEdmModel() });
    
        return builder;
    }

All needed API versioning services registered in DI container.

See endpoint configuration: endpoint configuration

See controller example: controller example

Any thoughts? What's the problem?

Answer 1

It's not entirely clear what BuildEdmModel() does, but it would appear that you are building it manually instead of via the VersionedODataModelBuilder. This is allowed, but know that you need to set the ApiVersionAnnotation. API Versioning for OData uses an EDM per API Version approach, which keeps everything clearly segregated. API Versioning determines how to match up the EDM by comparing the applied ApiVersionAnnotation with the resolved, incoming API Version. "There can be only one."

If you're building the EDMs yourself, you need to add this required annotation to the model itself:

edm.SetAnnotationValue(edm, new ApiVersionAnnotation(new ApiVersion(1, 0)));

If you only have a single version, this is pretty easy to build. If you have several versions, it gets more complex. The VersionedODataModelBuilder achieves this by creating a unioned set of all API versions, from all OData APIs, discovered through IActionDescriptorCollectionProvider. For every discovered OData API version, a set of IModelConfiguration instances are used to apply the configuration for that particular EDM in a particular API Version, including nothing at all (e.g. excluded). This is determined by the implementer (e.g. developer). Depending on the complexity of your application, you might use a single IModelConfiguration, one per entity, or none at all and just use the VersionedODataModelBuilder.DefaultModelConfiguration callback.

Regardless of the approach you use, if the ApiVersionAnnotation is set, you'll be back in business.

---

UPDATE: In response to the added images.

There are several additional points:

• If you inject VersionedODataModelBuilder from DI or explicitly resolve it from IServiceProvider, all of the work is done for you.
• If you just pass the VersionedODataModelBuilder to MapVersionedODataRoute as a parameter, it will do the right thing. Due to OData's prefix concept, the IModelConfiguration can vary by API version and path. Alternatively, you can call VersionedODataModelBuilder.GetEdmModels('path'). If there are no differences between the prefixes, then you're fine.
• The main issue appears to be that your controller name doesn't match up. API Versioning collates API by controller name because - well - it's the only consistent and reliable thing that can be used. This is important for matching up the corresponding EDM as well. It's not clear what PaymentsODataRouteAttribute actually does; however, if it sets the controller route parameter, then it should work. If not, then your controller name needs to match or you can use the provided [ControllerName("payments")] to satisfy the requirement. I assume the name of the corresponding entity set is Payments.
• No idea what EnableODataAttribute is. That doesn't appear to be a standard attribute. Inheriting from ODataController will enable the OData features.
• OData does not support the API Explorer out-of-the-box. If you're not also using the API Versioning API Explorer extensions for OData, configuring [ApiExplorerSettings(IgnoreApi = false)] will likely cause errors at runtime. The API Versioning extensions are aware that ODataController explicitly opts out of the API Explorer. By default, it will completely ignore the IgnoreApi setting so that you don't have to reconfigure and opt in every single ODataController. If you really want to use ApiExplorerSettingsAttribute, then you can configure the API Explorer extensions to honor it with ODataApiExplorerOptions.UseApiExplorerSettings, which defaults to false. If you don't change it to true, the setting is completely ignored which may include controllers that you intentionally marked as IgnoreApi = true.