没有 MediaTypeFormatter 可用于从 asp.net mvc webapi 中媒体类型为“text/html”的内容中读取“IEnumerable`1”类型的对象

Posted 2023-03-31

【中文标题】没有 MediaTypeFormatter 可用于从 asp.net mvc webapi 中媒体类型为“text/html”的内容中读取“IEnumerable`1”类型的对象

【英文标题】：No MediaTypeFormatter is available to read an object of type 'IEnumerable`1' from content with media type 'text/html in asp.net mvc webapi

【发布时间】：2020-01-09 07:55:11

【问题描述】：

我正在使用 Web API 和 ASP.NET MVC 一起创建一个 ASP.NET MVC Web 应用程序。我收到此错误：

没有 MediaTypeFormatter 可用于从媒体类型为“text/html”的内容中读取类型为“IEnumerable`1”的对象

studentController (mvcproject)

namespace Mvcproj.Controllers

   public class studentController : Controller
   
        public static HttpClient client = new HttpClient();

        // GET: Employes
        public ActionResult Index()
        
            client.BaseAddress = new Uri("http://localhost:1747/api");
            client.DefaultRequestHeaders.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            IEnumerable<studmodel> emplist;
            HttpResponseMessage response = client.GetAsync("studen").Result;
            Response.ContentType = "application/json";
            emplist = response.Content.ReadAsAsync<IEnumerable<studmodel>>().Result;          //here get an error
            response.EnsureSuccessStatusCode();
            return View(emplist);
        
    

索引.cshtml

@model IEnumerable<Mvcproj.Models.studmodel>

@
    ViewBag.Title = "Index";


<h2>Index</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.studid)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.username)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.password)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) 
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.studid)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.username)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.password)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new  /* id=item.PrimaryKey */ ) |
            @Html.ActionLink("Details", "Details", new  /* id=item.PrimaryKey */ ) |
            @Html.ActionLink("Delete", "Delete", new  /* id=item.PrimaryKey */ )
        </td>
    </tr>


</table>

输出：

http://localhost:1785/studen/index

studentController（API 项目）

namespace WebsApi.Controllers

    public class studentController : ApiController
    
        private studangEntities db = new studangEntities();

        // GET: api/studen
        public IQueryable<student> Getstudents()
        
            return db.students;
        

        // GET: api/studen/5
        [ResponseType(typeof(student))]
        public IHttpActionResult Getstudent(int id)
        
            student student = db.students.Find(id);
            if (student == null)
            
                return NotFound();
            

            return Ok(student);
        
      

输出：

http://localhost:1747/api/studen

<ArrayOfstudent xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/WebsApi.Models">
    <student>
        <password>admin@123</password>
        <studid>1017</studid>
        <username>admin</username>
    </student>
    <student>
        <password>devis</password>
        <studid>1025</studid>
        <username>devis</username>
    </student>

我也更改了application/xml - 但这导致了同样的错误。

当我调试时：

content  System.Net.Http.StreamContent

status code  System.Net.HttpStatusCode.NotFound

requestmessage Method: GET, RequestUri: 'http://localhost:1747/studen', Version: 1.1, Content: <null>, Headers:

Accept: text/json

我指的是这篇文章：https://docs.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/media-formatters 但错误没有解决

如何解决这个错误？？

【参考方案1】：

如你所见

requestmessage Method: GET, RequestUri: 'http://localhost:1747/studen', Version: 1.1, Content: , Headers:  Accept: text/json 

请求 URI 是 http://localhost:1747/studen，但您需要 http://localhost:1747/api/studen

在基本 URI 的末尾添加/

client.BaseAddress = new Uri("http://localhost:1747/api/");