asp.net - 从 OData api 获取项目计数

Question

我正在开发 ASP.NET Core 3.1 项目，我将 OData 用于其余 api。问题是，当我尝试使用以下查询获取集合中项目的计数时：http://someurl?$count=trueOData 会返回一个包含所有项目的数组，而不是计数。我阅读了很多关于 OData 的文章，但没有任何帮助，所以我很困惑。

score 1 · Accepted Answer

这是一个工作演示，您可以参考

安装包Microsoft.AspNetCore.OData- 版本 7.4.0

模型

 public class Student
{

    public Guid Id { get; set; }
    public string Name { get; set; }
    public int Score { get; set; }
}

Controller ，EnableQuery属性使端点具有 OData 功能

[Route("api/[controller]")]
[ApiController]
public class StudentsController : ControllerBase
{
    [HttpGet]
    [EnableQuery()]
    public IEnumerable<Student> Get()
    {
        return new List<Student>
        {
            new Student
            {
                Id = Guid.NewGuid(),
                Name = "Vishwa Goli",
                Score = 100
            },
            new Student
            {
                Id = Guid.NewGuid(),
                Name = "Josh McCall",
                Score = 120
            }
        };
    }
}

启动.cs

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers(mvcOptions =>
            mvcOptions.EnableEndpointRouting = false);

        services.AddOData();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseAuthorization();

        //app.UseEndpoints(endpoints =>
        //{
        //    endpoints.MapControllers();
        //});
        app.UseMvc(routeBuilder =>
        {
           // enable Selection, Expansion, Count, Filter, OrderBy for all routes under “odata/”
            routeBuilder.Expand().Select().Count().OrderBy().Filter();
            routeBuilder.MapODataServiceRoute("odata", "odata", GetEdmModel());
        });
    }

    private IEdmModel GetEdmModel()
    {
        var edmBuilder = new ODataConventionModelBuilder();
        edmBuilder.EntitySet<Student>("Students");

        return edmBuilder.GetEdmModel();
    }

结果：