数据模型未显示在HttpResponseMessage中 [英] Data models not showing up in HttpResponseMessage

问题描述

我正在尝试从.NET Core MVC应用程序进行简单的API调用：

 使用（var client = new HttpClient（））
 {
 client.BaseAddress = new Uri（ http：// localhost：49897）; 
 
 var response = client.GetAsync（ some-route）。Result; 
 var dataString = response.Content.ReadAsStringAsync（）。Result; //此处的数据异常。见下文。 
 
 [...] //反序列化dataString 
} 
  

client.GetAsync（route）成功命中了API操作方法，该方法最终完成了此操作：

  public HttpResponseMessage Get（[FromUri] BindingModel bindingModel）
 {
 List< SomeModel> resultObjects; 
 
 [...] //用数据
 
填充resultObjects Request.CreateResponse（HttpStatusCode.OK，resultObjects，new JsonMediaTypeFormatter（））; 
} 
  

但 dataString 结尾等于：

  {\ version\：{\ major\：1，＼ ＼ minor\：1，\ build\：-1，\ revision\：-1，\ majorRevision\：-1，\ minorRevision\： -1}，\ content\：{\ objectType\：\ System.Object，System.Private.CoreLib，Version = 4.0.0.0，Culture = neutral，PublicKeyToken = 7cec85d7bea7798e\ ，\ formatter\：{\ indent\：false，\ serializerSettings\：{\ referenceLoopHandling\：0，\ missingMemberHandling\：0，＼ ＼ objectCreationHandling\：0，\ nullValueHandling\：0，\ defaultValueHandling\：0，\转换器\：[]，\ preserveReferencesHandling\：0， \ typeNameHandling\：0，\ metadataPropertyHandling\：0，\ typeNameAssemblyFormat\：0，\ typeNameAssemblyFormatHandling\：0，\ constructorHandling\：0， \ contractResolver\：null，\ equalityComparer\：null，\ referenceResolver\：null，\ referenceResolverProvider\：null，\ traceWriter\：null， b binder\：空，\ serializationBinder\：空， \ error\：null，\ context\：{}，\ dateFormatString\：\ yyyy'-'MM'-'dd'T'HH'：'mm' ：'ss.FFFFFFFK\，\ maxDepth\：null，\格式化\：0，\ dateFormatHandling\：0，\ dateTimeZoneHandling\：3，＼ ＼ dateParseHandling\：1，\ floatFormatHandling\：0，\ floatParseHandling\：0，\ stringEscapeHandling\：0，\ culture\：{}} }}} 
  

或者，以JSON格式：

  {
版本：{
大写：1，
小写：1，
 [...] 
 }，
内容：{
 objectType： System.Object，System.Private.CoreLib，版本= 4.0.0.0，Culture = neutral，PublicKeyToken = 7cec85d7bea7798e 
格式程序：{
缩进：false，
序列化器设置：{
 [...] 
} 
} 
} 
} 
  

我的模型列表根本不存在。

确切是什么被退回，为什么我的列表中没有模型回应？我查看了一些在线资源，并且似乎按照它们显示的方式进行操作。这是一个相当不错的API调用，所以我不确定发生了什么。

解决方案

确切返回的是什么，为什么我的响应列表中没有模型？

返回的是 HttpResponseMessage 的JSON序列化版本，因为虽然Web API 2特别处理了这种类型，但 ASP.NET Core Web API却不。

准确地说， ASP.NET Core Web API支持返回以下类型：

• IActionResult


• ActionResult< T>


• <任何其他类型>

前两个经过特殊处理，但是该类型的第三个结果是JSON序列化并返回的，与您看到了。

相反， Web API 2支持以下特殊返回类型：

• void


• HttpResponseMessage


• IHttpActionResult


• <其他type>

正确的解决方案是更新代码以使用自定义的 IActionResult 实现，而不是返回原始的 HttpResponseMessage s。 您可能会发现本指南可以帮助您-在特别是， Microsoft.AspNetCore.Mvc.WebApiCompatShim NuGet软件包具有一个 ResponseMessageResult类，可用于转换您的Web API控制器的方法如下：

  public HttpResponseMessage Foo（Bar quux）
 { 
返回新的BazHttpResponseMessage（）; 
} 
  

为此：

< Pre class = lang-cs prettyprint-override> public IActionResult Foo（Bar quux）
{
return new ResponseMessageResult（new BazHttpResponseMessage（））;
}


这应允许您当前的代码按原样工作。

I'm trying to make a simple API call from a .NET Core MVC application:

using (var client = new HttpClient())
{
    client.BaseAddress = new Uri("http://localhost:49897");

    var response = client.GetAsync("some-route").Result;
    var dataString = response.Content.ReadAsStringAsync().Result; // Unexpected data here. See below.

    [...] // deserialize dataString
}

client.GetAsync(route) successfully hits an API action method, which ultimately does this:

public HttpResponseMessage Get([FromUri] BindingModel bindingModel)
{
    List<SomeModel> resultObjects;

    [...] // populate resultObjects with data

    return Request.CreateResponse(HttpStatusCode.OK, resultObjects, new JsonMediaTypeFormatter());
}

But dataString ends up equaling this:

"{\"version\":{\"major\":1,\"minor\":1,\"build\":-1,\"revision\":-1,\"majorRevision\":-1,\"minorRevision\":-1},\"content\":{\"objectType\":\"System.Object, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e\",\"formatter\":{\"indent\":false,\"serializerSettings\":{\"referenceLoopHandling\":0,\"missingMemberHandling\":0,\"objectCreationHandling\":0,\"nullValueHandling\":0,\"defaultValueHandling\":0,\"converters\":[],\"preserveReferencesHandling\":0,\"typeNameHandling\":0,\"metadataPropertyHandling\":0,\"typeNameAssemblyFormat\":0,\"typeNameAssemblyFormatHandling\":0,\"constructorHandling\":0,\"contractResolver\":null,\"equalityComparer\":null,\"referenceResolver\":null,\"referenceResolverProvider\":null,\"traceWriter\":null,\"binder\":null,\"serializationBinder\":null,\"error\":null,\"context\":{},\"dateFormatString\":\"yyyy'-'MM'-'dd'T'HH':'mm':'ss.FFFFFFFK\",\"maxDepth\":null,\"formatting\":0,\"dateFormatHandling\":0,\"dateTimeZoneHandling\":3,\"dateParseHandling\":1,\"floatFormatHandling\":0,\"floatParseHandling\":0,\"stringEscapeHandling\":0,\"culture\":{}}}}}"

Or, in JSON format:

{
    version: {
        major: 1,
        minor: 1,
        [...]
    },
    content: {
        objectType: "System.Object, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e"
        formatter: {
            indent: false,
            serializerSettings: {
                [...]
            }
        }
    }
}

My list of models isn't in there at all.

What exactly is being returned, and why isn't my list of models in the response? I've looked at several online resources, and I seem to be doing things the same way as they show. This is a pretty bread-and-butter API call, so I'm not sure what's going on.

解决方案

What exactly is being returned, and why isn't my list of models in the response?

What's being returned is a JSON-serialized version of your HttpResponseMessage, because while Web API 2 handles this type specially, ASP.NET Core web API does not.

To be precise, ASP.NET Core web API supports returning the following types:

• IActionResult
• ActionResult<T>
• <any other type>

The first two are treated specially, but the third results in that type being JSON-serialized and returned, exactly as you saw.

In contrast, Web API 2 supports the following special return types:

• void
• HttpResponseMessage
• IHttpActionResult
• <any other type>

The correct solution is to update your code to use a custom IActionResult implementation instead of returning raw HttpResponseMessages. You may find this guide aids you in doing so - in particular, the Microsoft.AspNetCore.Mvc.WebApiCompatShim NuGet package has a ResponseMessageResult class that allows you to convert your Web API controller method from this:

public HttpResponseMessage Foo(Bar quux)
{
    return new BazHttpResponseMessage();
}

to this:

public IActionResult Foo(Bar quux)
{
    return new ResponseMessageResult(new BazHttpResponseMessage());
}

which should allow your current code to work as-is.

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