OData integration with CosmosDb does not return expected result

Question

I have created a .NET Core 3.1 WebAPI application which connect with Azure Cosmos Db. The WebAPI is returning data from CosmosDb correctly. When I tried to integrate OData to this solution, and tried to query data using the Select method, it does not return expected result.

The following are my code:

StartUp.cs

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddOData();
            services.AddControllersWithViews();
            services.AddSingleton<ICosmosDbService>(InitializeCosmosClientInstanceAsync(Configuration.GetSection("CosmosDb")).GetAwaiter().GetResult());
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                   name: "default",
                   pattern: "{controller=ToDo}/{action=Index}/{id?}");

                endpoints.EnableDependencyInjection();
                endpoints.Select().Filter().OrderBy().Expand();
            });
        }

    }

WebAPI controller:

    [Produces("application/json")]
    [Route("api/[controller]")]
    [ApiController]
    public class ItemsController : ControllerBase
    {
        private readonly ICosmosDbService _cosmosDbService;
        public ItemsController(ICosmosDbService cosmosDbService)
        {
            _cosmosDbService = cosmosDbService;
        }

        // GET: api/<ItemsController>
        [HttpGet]
        [EnableQuery()]
        public async Task<IEnumerable<Item>> Get()
        {
            return await _cosmosDbService.GetItemsAsync("SELECT * FROM c");
        }
   }

When I try to retrieve data using the API call(https://localhost:44357/api/items), I am getting expected result:

[{"id":"5f4f5d02-9217-4591-8f8c-2af9fe7d9ae4","name":"Brush","description":"Brush your teeth every night","completed":true,"partitionKey":null},{"id":"6a5edfe3-9c84-4398-bed4-963dbb4a42e3","name":"Excercise","description":"Hit the gym in the evening","completed":true,"partitionKey":null}]

But when I try to use the OData method(https://localhost:44357/api/items?$select=name), I am not getting expected result. Instead, I am getting this:

[{"instance":null,"container":{},"modelID":"7c0ae376-1666-46f8-886f-9bf758824063","untypedInstance":null,"instanceType":null,"useInstanceForProperties":false},{"instance":null,"container":{},"modelID":"7c0ae376-1666-46f8-886f-9bf758824063","untypedInstance":null,"instanceType":null,"useInstanceForenter code hereProperties":false}]

Any idea why it is like this?

Michael Wang Michael Wang · Accepted Answer · 2021-01-21T08:16:34

There is incompatible situation with the JSON serializer in Asp.Net 3.1. Try to AddNewtonsoftJson.

services.AddControllers(mvcOptions =>
           mvcOptions.EnableEndpointRouting = false)
       .AddNewtonsoftJson();

OData integration with CosmosDb does not return expected result

StartUp.cs

WebAPI controller:

1 Answers