C# 如何检查模型中是否存在项目

我的控制器代码如下所示

    [HttpPost]
    public string Rating(int id, int rate, double avgrating)
    {
        rating rating = new rating();
        rating.date = DateTime.Now;
        rating.trendid = id;
        rating.rating1 = rate;
        rating.ratedby = User.Identity.Name;

        db.ratings.Add(rating);
        db.SaveChanges();

        return "{\"error\":false}";
    }

namespace SVMD.Models
{
using System;
using System.Collections.Generic;

public partial class rating
{
    public int id { get; set; }
    public System.DateTime date { get; set; }
    public int trendid { get; set; }
    public int rating1 { get; set; }
    public string ratedby { get; set; }

    public virtual trend trend { get; set; }
}
}

在视图中，我编写了如下代码

         @using (Html.BeginForm("Rating", "Article"))
            {
                <h4>Please Rate the Article</h4>
                <table id="temp" class: "table" cellspacing="0" cellpadding="7.5" style="text-align:center">
                    <tbody>
                        <tr class="rowc">
                            <td class="col1 cel1">Please Obselete</td>
                            <td class="col2 cel1">Not Very Useful</td>
                            <td class="col3 cel1">Helpful</td>
                            <td class="col4 cel1">Useful</td>
                            <td class="col5 cel1">Excellent</td>
                        </tr>
                        <tr class="rowb">
                            <td class="col1 cel1">
                                @Html.RadioButton("rate","1") 
                            </td>
                            <td class="col2 cel1">
                                @Html.RadioButton("rate","2")
                            </td>
                            <td class="col3 cel1">
                                @Html.RadioButton("rate","3")
                            </td>
                            <td class="col4 cel1">
                                @Html.RadioButton("rate","4")
                            </td>
                            <td class="col5 cel1">
                                @Html.RadioButton("rate","5")
                            </td>
                        </tr>

                    </tbody>
                </table>
                @Html.HiddenFor(m => Model.id);
                <button type="submit" class="btn btn-primary">Rate!</button>
            }

我的rating.cs如下所示

    [HttpPost]
    public string Rating(int id, int rate, double avgrating)
    {
        rating rating = new rating();
        rating.date = DateTime.Now;
        rating.trendid = id;
        rating.rating1 = rate;
        rating.ratedby = User.Identity.Name;

        db.ratings.Add(rating);
        db.SaveChanges();

        return "{\"error\":false}";
    }

namespace SVMD.Models
{
using System;
using System.Collections.Generic;

public partial class rating
{
    public int id { get; set; }
    public System.DateTime date { get; set; }
    public int trendid { get; set; }
    public int rating1 { get; set; }
    public string ratedby { get; set; }

    public virtual trend trend { get; set; }
}
}

我的问题是

如何通过填充为Model.ratings.Selectr=> r、 等级1.计数；到控制器以填充AVG？ 我只想在当前用户不在时显示“分级”选项卡 出现在ratedby列表中。我不知道如何做到这一点。

---

帮助我回答1的可能重复的感谢。但是如果我能在2上得到一些帮助，那就太好了。你能描述一下评级标签是什么吗？你是说第二段代码中的表单吗？是的，没错。我只想第二个代码片段，如果相应的用户以前没有评级。基本上是试图阻止一个人进行多重评级。你可以用它来解决代码片段将被执行的问题。但在这种情况下，您需要知道当前用户标识符。