在LINQ查询中使用模型值中的列表

Question

我正处于asp.net MVC开发的基础阶段.所以有时候我很难用简单的LINQ查询来工作.

scenario-

我有一个页面,有一些Image用户评论该图像(就像Facebook上的帖子包含用户的评论).

所以我从textarea保存这些注释并通过Ajax查询发送Image ID.

这是我的控制器动作方法 -

保存评论 -

   [HttpPost]
        public void SaveComment(CardModel card) {
            CardCommentTable commenttable = new CardCommentTable();
            commenttable.CardComment = card.cardComment;
            commenttable.FKcardID = card.cardID;
            db.CardCommentTables.InsertOnSubmit(commenttable);
            db.SubmitChanges();
        }

此注释保存在CardCommentTable具有Table的外键引用的表中,即保存图像.

在查看页面上呈现图像和其他字段 -

此查询呈现Image和其他使其成为An Image帖子的字段.像title,dateofsubmit,Like等等.

public ActionResult CardDetails(CardModel card) {

            var cardDetail = (from u in db.CardTables
                              where u.CardID == card.cardID
                              select new CardModel {
                                  cardID = u.CardID,
                                  cardHashCode = u.CardHashCode,
                                  cardDate = u.CardDate,
                                  cardFileName = u.CardFileName,
                                  cardFilePath = u.CardFilePath,
                                  cardTitle = u.CardTitle
                              }).ToList();
            return View(cardDetail);

        }

现在,在cardTable我还有一个列cardComment中,我希望从表中显示所有保存的注释CardCommentTable.

所以我试过 -

public ActionResult CardDetails(CardModel card) {
        var allsavedcomments= (from u in db.CardCommentTables
                           where u.FKcardID == card.cardID
                           select u).ToList();

        var cardDetail = (from u in db.CardTables
                          where u.CardID == card.cardID
                          select new CardModel {
                              cardID = u.CardID,
                              cardHashCode = u.CardHashCode,
                              cardDate = u.CardDate,
                              cardFileName = u.CardFileName,
                              cardFilePath = u.CardFilePath,
                              cardTitle = u.CardTitle,
                              cardComment = allsavedcomments // Trying to render all saved coments here.
                          }).ToList();
        return View(cardDetail);

    }

视图-

@model IEnumerable<FunRanger.Models.CardModel>

@foreach (var item in Model) {
    <script type="text/javascript">
        $(function () {
            $('#save-comment').click(function () {
                var textareavalue = $('#textarea-comment').val();
                $.ajax({
                    url: '/Home/SaveComment/',
                    type: 'post',
                    data: '&cardComment=' + textareavalue + '&cardID=' + '@item.cardID',
                    success: function (data) {
                        $('#all-comments').append(data);


                    }

                });

            });

        });
    </script>
    using (Html.BeginForm()) {
    @Html.ValidationSummary(true)


        @if (Model != null) {


                <h2 class="header-wrapmain">
                    @item.cardTitle
                </h2>

                    @item.cardDate.ToShortDateString()


                        <img src="@item.cardFilePath" />

                                <a href="#" class="@item.cardHashCode" rel="tooltip" data-placement="bottom" title="Filter by @item.cardHashCode">
                                    #@item.cardHashCode</a>



        }
        else {
            <div class="alert alert-danger">
                No More items to preview
            </div>
        }


    }

    <textarea class="span12" rows="5" id="textarea-comment" style="resize: none" placeholder="Enter a comment..."></textarea>

        <a href="javascript:;" id="save-comment" class="btn-primary btn">Save comment</a>

        <ol>
            <li>
                @item.cardComment
            </li>
        </ol>

}

如何List在此处将结果插入列中.

如何使用以上查询显示所有已保存的评论？

谢谢你的帮助.

Answer 1

我用外键关系船稍微翻新你的代码.这将节省您对数据库使用两个不同的查询(就像您现在正在做的那样).

所以如果你的数据库模型看起来像这样 -

那么你应该以这种方式在你的代码中有一个viewmodel -

public class ImageViewModel
{
    public string ImageId { get; set; }
    public string ImageUrl { get; set; }
    public List<string> Comments { get; set; }
}

你的控制器动作将返回所有结果应该像这样 -

 public class ListController : Controller
    {
        public ActionResult Index()
        {
            ImageViewModel model;
            using (SampleEntities entities = new SampleEntities())
            {
                model = (from p in entities.Images
                                     where p.ImageId == "1"
                                     select new ImageViewModel()
                                     {
                                         ImageId = p.ImageId,
                                         ImageUrl = p.ImageUrl,
                                         Comments = p.ImageComments.Select(pa => pa.Comment).ToList()
                                     }).FirstOrDefault();
            }

            return View(model);
        }
    }

最后,将显示所有图像结果的视图 -

@model MVC.Controllers.ImageViewModel

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<div>
    <h4>ImageViewModel</h4>
    <hr />
    <dl class="dl-horizontal">
        <dt>
            @Html.DisplayNameFor(model => model.ImageId)
        </dt>

        <dd>
            @Html.DisplayFor(model => model.ImageId)
        </dd>

        <dt>
            @Html.DisplayNameFor(model => model.ImageUrl)
        </dt>

        <dd>
            @Html.DisplayFor(model => model.ImageUrl)
        </dd>
        <br/>
        @foreach (var item in Model.Comments)
        {
            @item <br/>
        }

    </dl>
</div>

产出将是 -