Json 响应未在视图中输出，而是提示我下载文件

Question

我正在使用 WebRequest 从 FCC 读取 JSON 数据，以便可以将其输出到视图。这是我用于持有 FCC 许可证的自定义类：

     public class License
        {
            public string Name{ get; set; }
            public string Frn { get; set; }
            public string Callsign { get; set;}
            public string CategoryDesc { get; set; }
            public string ServiceDesc { get; set; }
            public string StatusDesc { get; set; }
            public DateTime ExpiredDate { get; set; }
            public string Id { get; set; }
            public string DetailUrl { get; set; }

        }

这是我用来读取 json 结果的控制器操作。
我现在将 Verizon Wireless 硬编码为搜索值：

public ActionResult GetLicenses()
        {
            var result = string.Empty;
            var url = "http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=jsonp&jsonCallback=?";

            var webRequest = WebRequest.Create(url);

            webRequest.Timeout = 2000;

            using (var response = webRequest.GetResponse() as HttpWebResponse)
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    var receiveStream = response.GetResponseStream();
                    if (receiveStream != null)
                    {
                        var stream = new StreamReader(receiveStream);
                        result = stream.ReadToEnd();
                    }
                }
            }
            return new ContentResult { Content = result, ContentType = "application/json" };

        }

这是视图。我试图枚举所有许可证并将它们输出到表中，但是当我转到 /Home/GetLicenses 时，它提示我下载文件：

@model IEnumerable<MvcApplication1.Models.License>

@{
    ViewBag.Title = "Licenses";
}

<h2>Licenses</h2>

<table>
    <tr>
        <th>
            Name
        </th>
        <th>
            Frn
        </th>
        <th>
            Callsign
        </th>
        <th>
            CategoryDesc
        </th>
        <th>
            ServiceDesc
        </th>
        <th>
            StatusDesc
        </th>
        <th>
            ExpiredDate
        </th>
        <th>
            DetailUrl
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Name)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Frn)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Callsign)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.CategoryDesc)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.ServiceDesc)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.StatusDesc)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.ExpiredDate)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.DetailUrl)
        </td>
    </tr>
}

</table>

如果我直接通过 jquery 的 getJSON 方法执行上述操作，则可以得到上述工作，但是我想看看是否可以将结果从控制器获取到视图，然后将其呈现在视图中。

这是结果变量中返回内容的示例：

?({
    "status": "OK",
    "Licenses": {
        "page": "1",
        "rowPerPage": "100",
        "totalRows": "1995",
        "lastUpdate": "Sep 21, 2011",
        "License": [
            {
                "licName": "CELLCO PARTNERSHIP (\"VERIZON WIRELESS\")",
                "frn": "",
                "callsign": "",
                "categoryDesc": "Satellite Earth Station",
                "serviceDesc": "",
                "statusDesc": "Active",
                "expiredDate": "",
                "licenseID": "2300007967",
                "licDetailURL": "http://licensing.fcc.gov/cgi-bin/ws.exe/prod/ib/forms/reports/swr031b.hts?prepare=&column=V_SITE_ANTENNA_FREQ.file_numberC/File+Number&q_set=V_SITE_ANTENNA_FREQ.file_numberC/File+Number/=/FCNNEW2000060800036"
            },
            {
                "licName": "CELLO PARTNERSHIP (\"VERIZON WIRELESS\")",
                "frn": "",
                "callsign": "",
                "categoryDesc": "Satellite Earth Station",
                "serviceDesc": "",
                "statusDesc": "Active",
                "expiredDate": "",
                "licenseID": "2300010661",
                "licDetailURL": "http://licensing.fcc.gov/cgi-bin/ws.exe/prod/ib/forms/reports/swr031b.hts?prepare=&column=V_SITE_ANTENNA_FREQ.file_numberC/File+Number&q_set=V_SITE_ANTENNA_FREQ.file_numberC/File+Number/=/FCNNEW2000083100048"
            },
            {
                "licName": "Cellco Partnership d/b/a Verizon Wireless",
                "frn": "0003290673",
                "callsign": "KE2XMC",
                "categoryDesc": "Experimental",
                "serviceDesc": "Experimental Developmental",
                "statusDesc": "Unknown",
                "expiredDate": "12/14/2000",
                "licenseID": "3000020853",
                "licDetailURL": "https://fjallfoss.fcc.gov/oetcf/els/reports/ELSSearchResult.cfm?callsign=KE2XMC"
            },
            {
                "licName": "Cellco Partnership d/b/a Verizon Wireless",
                "frn": "0003290673",
                "callsign": "WA2XPS",
                "categoryDesc": "Experimental",
                "serviceDesc": "Experimental Developmental",
                "statusDesc": "Unknown",
                "expiredDate": "12/14/2000",
                "licenseID": "3000020851",
                "licDetailURL": "https://fjallfoss.fcc.gov/oetcf/els/reports/ELSSearchResult.cfm?callsign=WA2XPS"
            },
            {
                "licName": "Cellco Partnership dba Verizon Wireless",
                "frn": "0003290673",
                "callsign": "KNKP866",
                "categoryDesc": "Mobile/Fixed Broadband",
                "serviceDesc": "Cellular",
                "statusDesc": "Cancelled",
                "expiredDate": "10/01/2005",
                "licenseID": "13328",
                "licDetailURL": "http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?__newWindow=false&licKey=13328"
            }
        ]
    }
})

我添加了此类：

 public class FCC
    {
        public string status { get; set; }
        public Licenses Licenses { get; set; }

    }

但我仍然得到无效的 JSON 原语。

 public ActionResult GetLicenses()
        {
            var result = string.Empty;
            var url =
                "http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=jsonp&jsonCallback=?";

            var webRequest = WebRequest.Create(url);

            webRequest.Timeout = 2000;
            webRequest.ContentType = "application/json";

            using (var response = webRequest.GetResponse() as HttpWebResponse)
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    var receiveStream = response.GetResponseStream();
                    if (receiveStream != null)
                    {
                        var stream = new StreamReader(receiveStream);
                        result = stream.ReadToEnd();
                    }
                }
            }

            FCC fcc = new FCC();

            if (result.StartsWith(@"?("))
            {
                result = result.Substring(2);
            }

            if (result.EndsWith(@")"))
            {
                result = result.Remove(result.Length - 1);
            }


            if (result != null)
            {
                JavaScriptSerializer serializer = new JavaScriptSerializer();
                fcc = serializer.Deserialize<FCC>(result);
            }
            return View(fcc.Licenses.License);


        }

Answer 1

通过从 ActionMethod 返回 ContentResult，您的浏览器将根据内容以适当的操作进行响应。在这种情况下，将像文件一样下载 JSON 字符串，因为它不是 HTML 文档。

如果您想在视图中呈现结果而不是通过 AJAX，那么您需要创建一个表示 WebRequest 响应数据的 C# 模型类，然后返回一个 ViewResult 并传递模型（或集合）模型）到视图。

我建议更改您的 ActionMethod 来执行如下所示的操作，并创建一个名为“Licenses”的视图

此外，您的示例响应有点诡计。它比原始许可证对象的数组更复杂，并且它用 ?() 包装。 JavaScriptSerializer 将仅反序列化它可以根据属性名称匹配的属性（也区分大小写）。由于 ?() 包装，我们需要将其删除，这样反序列化就不会中断。

因此，您需要相应地修改您的许可证对象：

public class FCC
{
    public string status {get;set;}
    public Licenses Licenses {get; set;}
}
public class License
{
    public string licName{ get; set; }
    public string frn { get; set; }
    public string callsign { get; set;}
    public string categoryDesc { get; set; }
    public string serviceDesc { get; set; }
    public string statusDesc { get; set; }
    public string expiredDate { get; set; } //JSON dates and C# Dates are very finicky
    public string licenseID { get; set; }
    public string licDetailURL { get; set; }
}

public class Licenses
{
    public int page {get; set;}
    public int rowPerPage {get; set;}
    public int totalRows {get; set;}
    public string lastUpdate {get; set;}
    public List<License> License {get; set;}
}


public ActionResult Licenses()
{
        var result = string.Empty;
        var url = "http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=jsonp&jsonCallback=?";

        var webRequest = WebRequest.Create(url);

        webRequest.Timeout = 2000;

        using (var response = webRequest.GetResponse() as HttpWebResponse)
        {
            if (response.StatusCode == HttpStatusCode.OK)
            {
                var receiveStream = response.GetResponseStream();
                if (receiveStream != null)
                {
                    var stream = new StreamReader(receiveStream);
                    result = stream.ReadToEnd();
                }
            }
        }

        FCC fcc = new FCC();

        if (result.StartsWith(@"?("))
        {
            result = result.Substring(2);
        }

        if (result.EndsWith(@")"))
        {
            result = result.Remove(result.Length - 1);
        }

        if(result != null)
        {
             JavaScriptSerializer serializer = new JavaScriptSerializer();
             fcc = serializer.Deserialize<FCC>(result);
        }
        return View(fcc.Licenses.License); //pass the data that your view needs

}

最后，您将需要更改 CSHTML 文件中的属性名称，因为新的许可证对象不再具有相同的属性名称。

AJAX 可能是另一个问题，但如果我遇到一个很好的例子，我会在这里发帖

Answer 2

我将尝试解决您的代码中的几个问题：

1. 您有一个返回 JSON 字符串的控制器操作，并且您已经定义了一些 Razor 视图，但该 razor 视图永远不会从该操作中调用。
2. 您正在查询返回 JSONP 的远程服务，而不是使用似乎更适合的 API 的 JSON 可能性。
3. 在获取远程资源期间，您会危及工作线程。

因此，让我们从视图模型开始：

public class License
{
    public string Name { get; set; }
    public string Frn { get; set; }
    public string Callsign { get; set; }
    public string CategoryDesc { get; set; }
    public string ServiceDesc { get; set; }
    public string StatusDesc { get; set; }
    public DateTime ExpiredDate { get; set; }
    public string Id { get; set; }
    public string DetailUrl { get; set; }
}

public class Licenses
{
    public License[] License { get; set; }
}

public class FCC
{
    public string status { get; set; }
    public Licenses Licenses { get; set; }
}

然后我们将拥有以下控制器：

public class HomeController : Controller
{
    public ActionResult Index()
    {
        using (var client = new WebClient())
        {
            var json = client.DownloadString("http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=json");
            var serializer = new JavaScriptSerializer();
            var model = serializer.Deserialize<FCC>(json);
            return View(model.Licenses.License);
        }
    }
}

请注意，我在 url 中不再指定旨在与 JSONP 一起使用的 jsonCallback 查询字符串参数，但我不这样做想要 JSONP，我想要 JSON。为此，我还设置了 format=json 参数。

最后，我们可以拥有以下 ~/Views/Home/Index.cshtml 视图：

@model IEnumerable<License>

<table>
    <thead>
        <tr>
            <th>
                Name
            </th>
            <th>
                Frn
            </th>
            <th>
                Callsign
            </th>
            <th>
                CategoryDesc
            </th>
            <th>
                ServiceDesc
            </th>
            <th>
                StatusDesc
            </th>
            <th>
                ExpiredDate
            </th>
            <th>
                DetailUrl
            </th>
            <th></th>
        </tr>
    </thead>
    <tbody>
        @Html.DisplayForModel()
    </tbody>
</table>

以及将为 Licenses 集合的每个元素呈现的相应显示模板 (~/Views/Home /DisplayTemplates/License.cshtml)：

@model License

<tr>
    <td>
        @Html.DisplayFor(x => x.Name)
    </td>
    <td>
        @Html.DisplayFor(x => x.Frn)
    </td>
    <td>
        @Html.DisplayFor(x => x.Callsign)
    </td>
    <td>
        @Html.DisplayFor(x => x.CategoryDesc)
    </td>
    <td>
        @Html.DisplayFor(x => x.ServiceDesc)
    </td>
    <td>
        @Html.DisplayFor(x => x.StatusDesc)
    </td>
    <td>
        @Html.DisplayFor(x => x.ExpiredDate)
    </td>
    <td>
        @Html.DisplayFor(x => x.DetailUrl)
    </td>
</tr>

好的，到目前为止我们已经有了地址点 1 和 2。

现在是第三个。此同步调用的问题在于以下行：client.DownloadString。这是一个阻塞调用。在 ASP.NET 应用程序中，阻止对远程资源的调用非常糟糕。在这里，您正在获取一些远程资源，这可能需要时间=>您将穿越网络边界、互联网防火墙……直到您到达远程 Web 服务器，该服务器本身为了满足请求将查询数据库……您明白了：它很慢。在这段时间里，您的 Web 应用程序一直处于等待状态，并且线程被垄断。请记住，您可以使用的工作线程数量有限，因此不要浪费它们。

解决这个非常严重的问题的方法是使用异步控制器和 I/O 完成端口。它们直接内置于 Windows 内核中，允许您执行 IO 密集型操作，而无需阻塞和独占服务器上的线程。

您的 HomeController 将变成以下样子：

public class HomeController : AsyncController
{
    public void IndexAsync()
    {
        var client = new WebClient();
        AsyncManager.OutstandingOperations.Increment();
        client.DownloadStringCompleted += (s, e) => 
        {
            AsyncManager.OutstandingOperations.Decrement();
            if (e.Error != null)
            {
                AsyncManager.Parameters["error"] = e.Error.Message;
            }
            else
            {
                var serializer = new JavaScriptSerializer();
                var model = serializer.Deserialize<FCC>(e.Result);
                AsyncManager.Parameters["licenses"] = model.Licenses.License;
            }
        };
        client.DownloadStringAsync(new Uri("http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=json"));
    }

    public ActionResult IndexCompleted(License[] licenses, string error)
    {
        if (!string.IsNullOrEmpty(error))
        {
            ModelState.AddModelError("licenses", error);
        }
        return View(licenses ?? Enumerable.Empty<License>());
    }
}

Answer 3

这是我所做的，它在 DIV 中向我显示 Json 数据...

您的控制器...

public JsonResult GetLicenses()
        {
            var result = string.Empty;
            const string url = "http://data.fcc.gov/api/license-view/basicSearch/getLicenses?searchValue=Verizon+Wireless&format=jsonp&jsonCallback=?";

            var webRequest = WebRequest.Create(url);

            webRequest.Timeout = 2000;

            using (var response = webRequest.GetResponse() as HttpWebResponse)
            {
                if (response != null && response.StatusCode == HttpStatusCode.OK)
                {
                    var receiveStream = response.GetResponseStream();
                    if (receiveStream != null)
                    {
                        var stream = new StreamReader(receiveStream);
                        result = stream.ReadToEnd();

                    }
                }
            }
            return Json(result,JsonRequestBehavior.AllowGet);

在 Action 中设置返回类型 Json 并输入 JsonResult

，如果您想通过 AJAX 调用它，那么这里是

$.ajax

<script type="text/javascript">
    $(document).ready(function () {
        $.ajax({
            type: 'GET',
            url: '@Url.Action("GetLicenses","Home")',
            success: function (data) {
                $('#content').html(data);
            },
            error: function (data) {
                $('#content').append(data);
            }
        });
    });

并确保您在 _Layout.cshtml 中引用 Jquery 文件。