在 MVC 视图中，根据键检索字典的值

Question

我正在尝试使用以下语句从字典中获取基于键的值：

它只是抛出 NULL 引用异常，但我确实有一个键值对 "MyKey"

@Model.DictionaryTest["MyKey"]

我应该使用词典列表吗？如果是这样，你能给我从中检索的语句吗？

更新—— 这是我作为模型传递的 class，在控制器中我正在填充字典。（我检查了值是否完整）

public class Dummy_PreHires_View_Model
{
    public Dictionary<string, string> DictionaryTest { get; set; }
}

这是字典上的数据之一，如果这有帮助，我已经尝试使用图片上提到的密钥，仍然抛出 NULL 异常： Dictionary data snap

我的控制器代码：

public ActionResult PreHires_Dummy()
        {
            ViewBag.PreHires_Dummy_class = "active";

            Dummy_PreHires_View_Model dpvm = new Dummy_PreHires_View_Model();
            Dummy_PreHires_Translate_Model dptm = new Dummy_PreHires_Translate_Model();

            dpvm.DictionaryTest = dptm.GetTranslatedData();

            return View(dpvm);
        }

Answer 1

我写了一个示例here。希望对你有所帮助。

型号：

using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;

namespace HelloWorldMvcApp {
    public class SampleViewModel {
        [Required]
        [MinLength(10)]
        [MaxLength(100)]
        [Display(Name = "Ask Magic 8 Ball any question:")]
        public string Question { get; set; }

        //See here for list of answers
        public string Answer { get; set; }

        public Dictionary<string, string> DictionaryTest { get; set; }
    }
}

控制器：

using System;
using System.Web.Mvc;
using System.Collections.Generic;

namespace HelloWorldMvcApp {
    public class HomeController : Controller {
        [HttpGet]
        public ActionResult Index() {
            SampleViewModel viewModel = new SampleViewModel();
            viewModel.DictionaryTest = new Dictionary<string, string>();
            viewModel.DictionaryTest.Add("key1", "value1");
            viewModel.DictionaryTest.Add("key2", "value2");
            return View(viewModel);
        }

        [HttpPost]
        public JsonResult GetAnswer(string question) {              
            int index = _rnd.Next(_db.Count);
            var answer = _db[index];
            return Json(answer);
        }

        private static Random _rnd = new Random();

        private static List<string> _db = new List<string> { "Yes", "No", "Definitely, yes", "I don't know", "Looks like, yes"} ;
    }
}

查看：

@model HelloWorldMvcApp.SampleViewModel
@{
    Layout = null;
}

<!DOCTYPE html>
<!-- template from http://getbootstrap.com/getting-started -->

<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>Bootstrap 101 Template</title>

        <!-- CSS Includes -->
        <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">

        <style type="text/css">

            .field-validation-error {
                color: #ff0000;
            }

        </style>
    </head>

    <body>
        <div class="container">
            <div class="col-md-6 col-md-offset-3">
                <h1>Hello Stranger</h1>

                @using (Html.BeginForm())
                {
                    <div class="form-group">
                        @Html.LabelFor(m => m.Question)
                        @Html.TextBoxFor(model => model.Question, new {@class="form-control"}) 
                        @Html.ValidationMessageFor(model => model.Question)
                        @Model.DictionaryTest["key1"]
                        @Model.DictionaryTest["key2"]
                    </div>

                    <button type="button" class="btn btn-success submit">Ask</button>
                }

                <br/><br/>
                <div class="alert alert-warning fade">
                    <img src="http://entechprod.blob.core.windows.net/dotnetfiddle/morpheus.jpg" style="max-width:100%;"/><br/><br/>
                    <strong><span class="alert-content"></span></strong>
                </div>
            </div>
        </div>

        <!-- JS includes -->
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
        <script src="//netdna.bootstrapcdn.com/bootstrap/3.1.1/js/bootstrap.min.js"></script>

        <script src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.11.1/jquery.validate.min.js"></script>
        <script src="//ajax.aspnetcdn.com/ajax/mvc/4.0/jquery.validate.unobtrusive.min.js"></script>

        <script type="text/javascript">

            function openAlert(txt) {
                $('.alert-content').text(txt);
                $('.alert').addClass('in');
            }

            function closeAlert() {
                $('.alert').removeClass('in');
            }

            $(function(){
                var answer = '@Model.Answer';

                if(answer && answer != '') 
                    openAlert(answer);

                $('#Question').change(closeAlert);
                $('#Question').keyup(closeAlert);

                $('.submit').click(function(){
                    if($('form').valid()) {

                        $.ajax({
                            url: '@Url.RouteUrl(new{ action="GetAnswer", controller="Home"})',
                            data: {Answer: '', Question: $('#Question').val()},
                                type: 'POST',
                                dataType: 'json',
                                contentType: "application/json; charset=utf-8",
                                success: function(resp) {
                                openAlert(resp);
                        }});
                    }
                    else {
                        closeAlert();
                    }
                });

            });

        </script>
    </body>
</html>

在 MVC 视图中，根据键检索字典的值

Retrieve value of Dictionary based on key, in MVC view

c#

asp.net-mvc

dictionary

key

asp.net-mvc-views