Question

我有这个问题类。有吗

public class Issue
{
    public int IssueId { get; set; }

    [Required]
    public string ReporterName { get; set; }

    [Required]
    public string Description { get; set; }

    public int? IssueTypeId { get; set; }

    public virtual IssueType type { get; set; }
}

然后这是我的视图，所以我可以更改IssueTypeId的值。但是，当我尝试使用控制器中的代码将其保存在数据库中时，我收到一条错误消息，指出仍然需要ReporterName和Description。我怎样才能更新数据库中的一个特定值，在本例中为IssueTypeId？

@using (Html.BeginForm())
{
   @Html.AntiForgeryToken()

<div class="form-horizontal">
    <h4>Issue</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    @Html.HiddenFor(model => model.IssueId)

    <div class="form-group">
        @Html.LabelFor(model => model.IssueTypeId, "IssueTypeId", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("IssueTypeId", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.IssueTypeId, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Save" class="btn btn-default" />
        </div>
    </div>
</div>

}

我在控制器中的代码

public ActionResult AssignFixer(int issueId, int issueTypeId)
    {
        var issue = new Issue { IssueId = issueId , IssueTypeId= issueTypeId};

        using (var newContext = new SystemContext())
        {
            newContext.Issues.Attach(issue);
            newContext.Entry(issue).Property(i => i.IssueTypeId).IsModified = true;
            newContext.SaveChanges();
        }
        return View(issue);
    }

Answer 1

而不是在issue附加newContext.Issues。首先获取实例然后更新它。喜欢：

var existingIssue = newContext.Issues.Where(i => i.IssueId == issueId).FirstOrDefault();

existingIssue.IssueTypeId = issueTypeId;

newContext.SaveChanges();

如何在数据库

1 个答案: