部分视图传viewbag,从ViewBag传递一个值到一个局部视图

短命女 2022-08-30 11:13 121阅读 0赞

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So my Controller's code is as follows:

private CommunityModelsContext dbCommunities = new CommunityModelsContext();

// GET: /Home/

public ActionResult Index()

//retrieve the Communities

ViewBag.Communities = dbCommunities.Communities.ToList();

return View();

And my View has this all important line to start the Partial View

@\{Html.RenderPartial("CommunitiesPartial");\}

and in the Partial view, I'm trying to create a DropDownList (I'm still learning, this is a practice app just to see if I've understood the concepts from the asp.net tutorial), that will then take this List of entities, display one field, gets the value from the Other ("Name" and "id")

@model BuildingManagement.Models.Community.Community

@Html.BeginForm("Index","CommunityController")

@Html.LabelFor(x => x.Name)

@Html.DropDownList("Community" , new SelectList(Model.Name,"id","Name"))

Now this throws a NullReference Exception, the model is null. There is no model in the Index page and it is not bound to anything, however, the data is being sent through the ViewBag.

Ideas please?

解决方案

Your partial is strongly typed to a model (BuildingManagement.Models.Community.Community). So you need to pass this model to the main view first:

public ActionResult Index()

//retrieve the Communities

ViewBag.Communities = dbCommunities.Communities.ToList();

BuildingManagement.Models.Community.Community model = ... retrieve your model

return View(model);

and then since you decided to use ViewBag instead of view models you need to keep using the value you defined in this ViewBag inside your partial:

@Html.DropDownList("Community", new SelectList(ViewBag.Communities, "id", "Name"))

Of course a much better approach is to use a view model:

public class CommunityViewModel