IFeatureCollection 已被处置。对象名称：'Collection'。从控制器到视图

Question

我对这一切都是陌生的，并且正处于制作此 Web 应用程序的早期阶段。这仅供我个人使用。我正在尝试在视图中显示网络 api 调用的结果。 api 调用工作正常。我可以看到数据从服务返回并被放置在 DTO 中。它从服务到控制器，但我不确定为什么每次我尝试将数据从控制器发送到视图时，我都会遇到相同的异常：

IFeatureCollection has been disposed. Object name: 'Collection'.

谁能告诉我这是什么意思，我该如何解决这个问题？

这是我的 Startup.cs


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.AddHttpClient("mapQUrl", client => { client.BaseAddress = new Uri("https://www.mapquestapi.com/geocoding/v1/address?"); });
    services.AddHttpClient("climaUrl", client => { client.BaseAddress = new Uri("https://api.climacell.co/v3/weather/nowcast?"); });
    services.AddControllersWithViews();
    services.AddScoped<IServices, Services>();

}

// 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=Home}/{action=Index}/{id?}");
    });
}

这是我的服务：

public async Task<List<ClimaCellDto>> GetTemp(MapQuestFlatDto loc)
{
    List<ClimaCellDto> dataObjects = new List<ClimaCellDto>();
    
    var client = _clientFactory.CreateClient("climaUrl");
    string attr = "unit_system=us&timestep=5&start_time=now&fields=temp&";
    var url = client.BaseAddress + attr + climaUrlParameters;

    // Add an Accept header for JSON format.
    client.DefaultRequestHeaders.Accept.Add(
    new MediaTypeWithQualityHeaderValue("application/json"));

    HttpResponseMessage response = await client.GetAsync(url);  // Blocking call! Program will wait here until a response is received or a timeout occurs.
    if (response.IsSuccessStatusCode)
    {
        // Parse the response body.
        var strContent = await response.Content.ReadAsStringAsync();  //Make sure to add a reference to System.Net.Http.Formatting.dll

        dataObjects = JsonConvert.DeserializeObject<List<ClimaCellDto>>(strContent);
        return dataObjects;
    }
    else
    {
        Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
    }

    return dataObjects;
}

这是从服务接收数据并将其发送到视图的控制器方法：

[HttpPost]
public async void getLoc ([FromBody]ZipDto obj)
{    
    var zip = Int32.Parse(obj.zip);
    var location = await _services.GetLatLng(zip);
    var climate =  await _services.GetTemp(location);
    ShowResults(climate);
}

public IActionResult ShowResults(List<ClimaCellDto> data)
{
    try
    {
        return View(data);
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

这是视图：

    @model IEnumerable<Weather_web_app.DTOs.ClimaCellDto>

@{
    ViewData["Title"] = "ShowResults";
}

<h1>ShowResults</h1>

<p>
    <a asp-action="Create">Create New</a>
</p>
<table class="table">
    <thead>
        <tr>
            <th>
                @Html.DisplayNameFor(model => model.lat)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.lon)
            </th>
            <th></th>
        </tr>
    </thead>
    <tbody>
@foreach (var item in Model) {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.observation_time.value)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.temp.value)
            </td>
        </tr>
}
    </tbody>
</table>

这是调用堆栈：

at Microsoft.AspNetCore.Http.Features.FeatureReferences`1.ThrowContextDisposed()
    at Microsoft.AspNetCore.Http.Features.FeatureReferences`1.ContextDisposed()
    at Microsoft.AspNetCore.Http.Features.FeatureReferences`1.Fetch[TFeature,TState](TFeature& cached, TState state, Func`2 factory)
    at Microsoft.AspNetCore.Http.DefaultHttpContext.get_RequestServices()
    at Microsoft.AspNetCore.Mvc.Controller.get_TempData()
    at Microsoft.AspNetCore.Mvc.Controller.View(String viewName, Object model)
    at Microsoft.AspNetCore.Mvc.Controller.View(Object model)

我已经在网上寻找了几个小时的人有类似的问题，但我没有找到任何东西。任何帮助是极大的赞赏。提前致谢。

Answer 1

您似乎没有正确使用控制器方法。您需要 return 视图形成端点方法本身。目前，您只是 return 从没有向上传播的 ShowResults 方法中获取信息。试试这个（看看 return 类型）：

[HttpPost]
public async Task<IActionResult> getLoc ([FromBody]ZipDto obj)
{    
    var zip = Int32.Parse(obj.zip);
    var location = await _services.GetLatLng(zip);
    var climate =  await _services.GetTemp(location);
    return ShowResults(climate);
}

public IActionResult ShowResults(List<ClimaCellDto> data)
{
    try
    {
        return View(data);
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

此外，我建议的另一件事是重定向到 GET 方法，而不是直接从 POST 端点 return 访问视图。

IFeatureCollection 已被处置。对象名称：'Collection'。从控制器到视图

IFeatureCollection has been disposed. Object name: 'Collection'. going from controller to view

c#

.net-core-3.1