jQueryajax呼叫getAPI回傳Task<ActionResult<List<ApiObject>>>不斷收到500錯誤回應-有解無憂

HTML：

<div id="api-calls" class="ui-drop-shadow">
    <button id="ajax" class="form-control">ajax call</button>
</div>

jQuery 呼叫如下：

on(ajax, "click", function(event) { 
          alert('ajax');
           $.ajax({ 
               type: "GET",
               data: {SiteId: 8},
               dataType: "json",
               //dataType: "application/json, text/plain, */*",
               //dataType: "jsonp",
               //url: "https://localhost:44310/api/site/search?SiteId=8",
               url: "https://localhost:44310/api/site/search",
               success: function(data){        
                  alert(data);
               }
           });
        });

ASP.NET 站點控制器：

[HttpGet("[action]")]
public async Task<ActionResult<List<ApiObject>>> Search(int? SiteId)
{
 //Database logics that get to the 'recList' record list... all worked

 // finally, construct a list of the ApiObject for return, this is where the call failed
 // every time.
 recAPIList = recList.Select(a => new ApiObject()
            {
                ApiObjectId = a.ObjectId,
                Description = a.Description,
                Name = a.Name,
                IsDisabled = a.IsDisabled,
            })
            .ToList();

            return Ok(recAPIList);
}

如您所見，我已經dataType在 ajax 呼叫中嘗試了各種組合，但是所有這些組合都在 ASP.NET 控制器中構造回傳 APIObjects 串列的最后一步失敗。

檢查后的網路回應給出了以下錯誤：

{"Type":null,"Title":"An unexpected error occurred!","Status":500,
"Detail":"The Instance value should be used to identify the problem when contacting support.\r\n
System.InvalidOperationException: Sequence contains more than one element\r\n   
at System.Linq.ThrowHelper.ThrowMoreThanOneElementException()\r\n   
at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)\r\n   
at Controllers.SiteController.<>c__DisplayClass5_0.<Search>b__7(Site a) 
in \\Controllers\\SiteController.cs:line 167\r\n   
at System.Linq.Enumerable.SelectListIterator`2.ToList()\r\n   
at lambda_method(Closure , Object )\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)\r\n   
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)\r\n   
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)","Instance":"urn:nebraskadss:error:5eae0ea1-af8a-4cb9-9532-2060c922af93","Extensions":{}}

我還嘗試在控制器.ToList() Linq中用 for 回圈替換該陳述句以創建 ApiObjects 串列，但仍然以相同的錯誤回應失敗。

我想補充一點，這個端點來自一個現有的作業應用程式，它具有 asp.net core 后端和 angular 前端，它用于檢索物件串列。我發布這個問題的唯一原因是這個例外只發生在我從 jQuery 呼叫它時！

uj5u.com熱心網友回復：

如果你仔細閱讀：

序列包含多個元素

和

在 System.Linq.Enumerable.Single

這意味著您正在.Single()對 Collection 或 Enumerable 物件進行操作，這是允許的，但是該 Collection 或 Enumerable 物件會產生2 個或更多 items。

Single()強制 1 結果。如果它找到 0 個結果，或者 2 個或更多結果，那么它會拋出錯誤。您要么需要修復集合，或者如果不可能，請考慮使用First()代替Single().

最后，看起來錯誤也是由您未顯示的代碼引起的。如果recList是查詢的結果，那么您需要修復該查詢。

uj5u.com熱心網友回復：

你必須改變ajax請求

            $.ajax({     
               url: "https://localhost:44310/api/site/search?siteId=8",
               type: "GET",
                dataType: "json",
                    success: function(data){        
                  alert( JSON.stringify(data));
               }

或保留 ajax 但更改操作標題

[HttpGet("~/api/site/search/{siteId?}")]
public async Task<ActionResult<List<ApiObject>>> Search(int? siteId)

轉載請註明出處，本文鏈接：https://www.uj5u.com/shujuku/347667.html

標籤：查询阿贾克斯 asp.net-core-webapi

上一篇：試圖將資料傳遞給ajax函式，但不能

下一篇：使用onclick更新