从两个表中填充一个下拉列表 [英] Populate single dropdown from two tables

问题描述

该方案是：

数据存储在数据库中的项目和邻里表都。
现在，我想填充项目编号和项目名称和neighbourhoodId和邻里的名字下拉列表。

Data is stored in database in project and neighbourhood tables both. Now, i want to populate dropdown with project id and project name and neighbourhoodId and neighbourhood name.

我是对的，现在通过viewBag发送这样的：

i am right now sending through viewBag like this:

ViewBag.NeighbourhoodId = new SelectList(allNeighbourhood(), "Id", "NeighbourhoodName");

视图页面上，让下拉填充是这样的：

on view page, getting dropdown populated like this:

@Html.DropDownList("Locations", ViewBag.NeighbourhoodId as SelectList, "Select a location")

现在，如何发送另一个viewBag在这个DROPDOWNLIST。

Now,how to send another viewBag in this dropdownList.

二疑问句，我的下拉列表是局部视图于是，我像这样将数据发送到局部视图：

Second ques, My dropdown is in partial view So, i am sending data to partial view like this:

@Html.Partial("_CommentBoxSection",new Neighbourhood())

如何发送新的项目（））与邻里一起。有没有在那里我可以将它们的同时发送的​​任何局部过载。
我已经看到了关于这个称号一些职位，但它们是一些不同的东西
我最近尝试了这一点：

how to send new Project()) along with neighbourhood. Is there any overload of partial where i can send both of them. i have seen some posts relating to this title but they are something different I have recently tried this:

 public class ProjectAndNeighbourhoodListItemViewModel
{
    public Project Project { get; set; }
    public Neighbourhood Neighbourhood { get; set; }
    public string ProjectName { get; set; }
    public int Id { get; set; }
    public bool IsSelected { get; set; }
  //  public IEnumerable<SelectListItem> ToSelectListItem { get; set; }
    public SelectListItem ToSelectListItem()
    {
        return new SelectListItem
        {
            Text = Project.ProjectName,
            Value = Neighbourhood.Id.ToString(),
            Selected = IsSelected
        };
      }  
    }

和视图页面上直接

 @model @model IEnumerable<ProjectAndNeighbourhoodListItemViewModel>
 @Html.DropDownList("Locations", Model.Select(m => m.ToSelectListItem()), "Select a location")

但得到System.ArgumentNullException值不能为空我没有code控制器中我一定要通过在控制器的东西太

but getting System.ArgumentNullException value cannot be null i have no code in controller do i have to pass something in controller too

推荐答案

不要使用ViewBag将值传递到您的视图，使用的ViewModels相反，它是干净多了。该视图模型也是创建SelectListItems的好地方。创建或在您的控制器映射视图模型。

Do not use ViewBag to pass values to your view, use ViewModels instead, it is much cleaner. The ViewModel is also a good place to create your SelectListItems. Create or map the ViewModel in your controller.

// ViewModel for a single selectable entry
public class ProjectAndNeighbourhoodListItemViewModel {

    public string ProjectName { get; set; }

    public long NeighbourhoodId { get; set; }

    public bool IsSelected { get; set; }

    public SelectListItem ToSelectListItem() {
        return new SelectListItem {
            Text = ProjectName,
            Value = NeighbourhoodId.ToString(),
            Selected = IsSelected
        }
    }
}

在您的Razor视图：

In your Razor View:

@model IEnumerable<ProjectAndNeighbourhoodListItemViewModel>
@* Would be even better to use a wrapper model that contains the collection of list items as property! *@

@Html.DropDownList("Locations", Model.Select(m => m.ToSelectListItem()) , "Select a location")

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