c# - MVC 添加和删除子集合中的项目

Question

我在将数据绑定(bind)到集合项的集合时遇到了问题(我也无法正确表述我的问题)。让我们通过使用 psudo 模型的示例来简化每个人的操作。

假设我有以下示例模型:

public class Month()
{
    public int ID { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Week> Weeks { get; set; }
}

public class Week()
{
    public int ID { get; set; }
    public int MonthID { get; set; }
    public String Name { get; set; }
    public virtual ICollection<Day> Days { get; set; }
}

public class Day()
{
    public int ID { get; set; }
    public String Name { get; set; }
}

...和一个示例 View 模型:

public class EditMonthViewModel()
{
    public Month Month { get; set; }
    public List<Week> Weeks { get; set; }
    public List<Day> AllDays { get; set; }
}

编辑操作/ View 的目的是让用户能够编辑月份、分配给月份的周数，以及从某个月的周数中添加和删除天数。 View 可能会有所帮助。

@model myProject.ViewModels.EditMonthViewModel

//...
@using (Html.BeginForm())
{
    //Edit Month Stuff...

    @for(int i = 0; i < Model.Weeks.Count(); i++)
    {
        <h2>@Model.Weeks[i].Name</h2>
        @Html.EditorFor(model => Model.Weeks[i].Name)

        //loop through all possible days
        //Select only days that are assigned to Week[i] 
        @for(int d = 0; d < Model.AllDays.Count(); d ++)
        {
            //This is the focus of this question.  
            //How do you bind the data here?
            <input type="checkbox"
                   name="I have no idea" 
                   @Html.Raw(Model.Weeks[i].Days.Contains(Model.AllDays[d]) ? "checked" : "") />
        }
    }
}

Controller 操作方法

public ActionResult Edit(int id)
{
    var viewModel = new EditMonthViewModel();
    viewModel.Month = db.Months.Find(id);
    viewModel.Weeks = db.Weeks.Where(w => w.MonthID == id).ToList();

    viewModel.AllDays = db.Days.ToList();
}

[HttpPost]
public ActionResult Edit(EditMonthViewModel viewModel)
{
    var monthToUpdate = db.Months.Find(viewModel.Month.ID);
    //...

    if(viewModel.Weeks != null)
    {
        foreach (var week in viewModel.Weeks)
        {
            var weekToUpdate = monthToUpdate.Weeks.Single(w => w.ID == week.ID);
            //...

            /*So, I have a collection of weeks that I can grab, 
              but how do I know what was selected? My viewModel only has a 
              list of AllDays, not the days selected for Week[i]
            */
        }
}

我如何确保在提交表单时所选日期将绑定(bind)到该周？

Answer 1

看起来最简单的事情就是让表单的目标是填充 IEnumerable<DayModel> 类型的数据结构。 , 其中DayModel定义为:

public class DayModel
{
    public int WeekId { get; set; }
    public int DayId { get; set; }
    public bool IsIncluded { get; set; }
}

在大多数情况下，您可以保持 Razor 代码不变，但是当涉及到呈现复选框时，您可以执行如下操作:

@{
    var modelIdx = 0;
}

// ...

<input type="hidden" name="days[@modelIdx].WeekId" value="@Model.Weeks[i].Id" />
<input type="hidden" name="days[@modelIdx].DayId" value="@Model.AllDays[d].Id" />
<input type="checkbox" name="days[@modelIdx].IsIncluded" value="@(Model.Weeks[i].Days.Contains(Model.AllDays[d]) ? "checked" : "")" />
@{ modelIdx++; }

然后，您发布到的 Controller 操作可能具有此签名:

[HttpPost]
public ActionResult Edit(IEnumerable<DayModel> days)
{
    //...
}

对我有帮助的是永远不要混淆 View 模型，它应该只用于 View 模型(通常是 GET 操作)和非 View 模型(我们称之为普通模型)。避免让您的 POST 操作尝试绑定(bind)到 View 模型，这将大大简化您的生活。