_Layout and Partial View - asp.net-mvc

Using an MVC5 application and I am trying to load a model within a partial view that is also within the _layout page. This doesn't seem to work as it conflicts with other models loaded up in different views.
I found an alternative with ViewBags, but it's messy and I don't think it's the best approach. Is there a way to load up a partial view within a model that's inside the _layout page so the model loaded from the partial view doesn't conflict with another model?
Updated:
What I'm trying to do is this:
In the _layout page. I'm trying to use an image carousel which is supplied by bootstrap to be interactive with the user (so the user can change the images, titles, and sub-titles).
I created a model to store the data, such as the title, etc. :
public class BannerEditor
{
public int ID { get; set; }
[Display(Name="Title")]
[StringLength(150)]
public string title { get; set; }
[Display(Name = "Sub-Title")]
[StringLength(300)]
public string subTitle { get; set; }
[Display(Name = "Image Path")]
public string imgPath { get; set; }
[Display(Name= "Starting Banner")]
public int startBanner { get; set; }
}
Then for my partial View I wrote some code and tried to load the model.:
#model IEnumerable<webby.Models.BannerEditor>
#foreach (var item in Model)
{
if (item.startBanner == 1)
{
<div class="item active">
<img src=#item.imgPath alt="...">
<div class="carousel-caption">
<h3>#item.title</h3>
<p>#item.subTitle</p>
</div>
</div>
}
else
{
<div class="item">
<img src=#item.imgPath alt="...">
<div class="carousel-caption">
<h3>#item.title</h3>
<p>#item.subTitle</p>
</div>
</div>
}
}
then in my _Layout page, I just added the Partial.
<div class="carousel-inner">
#Html.Partial("BannerLoad")
Here is the controller:
public ActionResult BannerLoad()
{
return PartialView(db.BannerEditors.ToList())
}
It gives me an error stating that it cannot load the Articles model into my partial view. The model that it needs to load is the BannerEditor. Since my _layout is loaded into every page, and the partial view is loading a model. The partial view's model conflicts with every other loaded model. The models name is "Articles".
Is there a way around this?

Use child actions for this kind of thing. They're like partial views, but they get their own context, allowing you to fetch and work with whatever model you need to without affecting the rest of the page:
Controller
[ChildActionOnly]
public ActionResult BannerLoad()
{
var banners = db.BannerEditors.ToList();
return PartialView(banners);
}
BannerLoad.cshtml
#model IEnumerable<Namespace.To.BannerEditor>
<!-- HTML to display your banners -->
_Layout.cshtml
#Html.Action("BannerLoad");
All that looks pretty similar to what you already have, but there's some key differences:
Partials don't work with actions, that's actually what makes a child action a child action and not a partial. It seems in your current code that you're expecting Html.Partial to render your BannerLoad action, but it will never do that. It will only dump the content from BannerLoad.cshtml onto the page, which because it never got fed an appropriate model, will cause an error.
Partials don't have their own context (because they don't work within a separate action), so they must receive their model from the parent view. If you don't pass a model in (which you aren't), they are automatically passed the "current" model. This will be whatever model the view the main action is using and will obviously change action to action. You cannot set a model on _Layout.cshtml, for example, and have that passed in, as that's not the origin point.
Even if you could set the model on something like _Layout.cshtml, that would only work for that one partial. If you had any other partials, you're still out of luck.

Related

How to render a child collection in a view so that it rolls back into the parent model upon post?

Let's say I have a model hierarchy like so:
public class TabModel
{
public PolicyModel Policy {get;set;}
}
public class PolicyModel
{
public IEnumerable<PersonModel> Insured {get;set;}
}
public class PersonModel
{
public string Name {get;set;}
}
and I want to render a grid in the view with a editor for Person Name right in the grid.
I know that if I can just get the html to be like so:
<input name="Policy.Insured[0].Name" />
<input name="Policy.Insured[1].Name" />
...
etc
that upon post, my main model will have a policy and that policy will have some insured with names.
What in my razor do I call to make this happen automagically™?
I'd bet a dozen donuts there's something in the framework that knows about Collection[N].PropertyName when iterating over a collection but I don't know how to invoke it.
If I put:
#Html.EditorFor(model => model.Policy.Insured)
and in the Views\Shared\EditorTemplates folder put a PersonModel.cshtml, then in that file create my editors, it works as I hoped.

ChildActionOnly attribute not working [duplicate]

When would you use the attribute ChildActionOnly? What is a ChildAction and in what circumstance would you want restrict an action using this attribute?
The ChildActionOnly attribute ensures that an action method can be called only as a child method
from within a view. An action method doesn’t need to have this attribute to be used as a child action, but
we tend to use this attribute to prevent the action methods from being invoked as a result of a user
request.
Having defined an action method, we need to create what will be rendered when the action is
invoked. Child actions are typically associated with partial views, although this is not compulsory.
[ChildActionOnly] allowing restricted access via code in View
State Information implementation for specific page URL.
Example: Payment Page URL (paying only once)
razor syntax allows to call specific actions conditional
With [ChildActionOnly] attribute annotated, an action method can be called only as a child method from within a view. Here is an example for [ChildActionOnly]..
there are two action methods: Index() and MyDateTime() and corresponding Views: Index.cshtml and MyDateTime.cshtml.
this is HomeController.cs
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "This is from Index()";
var model = DateTime.Now;
return View(model);
}
[ChildActionOnly]
public PartialViewResult MyDateTime()
{
ViewBag.Message = "This is from MyDateTime()";
var model = DateTime.Now;
return PartialView(model);
}
}
Here is the view for Index.cshtml.
#model DateTime
#{
ViewBag.Title = "Index";
}
<h2>
Index</h2>
<div>
This is the index view for Home : #Model.ToLongTimeString()
</div>
<div>
#Html.Action("MyDateTime") // Calling the partial view: MyDateTime().
</div>
<div>
#ViewBag.Message
</div>
Here is MyDateTime.cshtml partial view.
#model DateTime
<p>
This is the child action result: #Model.ToLongTimeString()
<br />
#ViewBag.Message
</p>
if you run the application and do this request http://localhost:57803/home/mydatetime
The result will be Server Error like so:
This means you can not directly call the partial view. but it can be called via Index() view as in the Index.cshtml
#Html.Action("MyDateTime") // Calling the partial view: MyDateTime().
If you remove [ChildActionOnly] and do the same request http://localhost:57803/home/mydatetime it allows you to get the mydatetime partial view result:
This is the child action result. 12:53:31 PM
This is from MyDateTime()
You would use it if you are using RenderAction in any of your views, usually to render a partial view.
The reason for marking it with [ChildActionOnly] is that you need the controller method to be public so you can call it with RenderAction but you don't want someone to be able to navigate to a URL (e.g. /Controller/SomeChildAction) and see the results of that action directly.
FYI, [ChildActionOnly] is not available in ASP.NET MVC Core.
see some info here
A little late to the party, but...
The other answers do a good job of explaining what effect the [ChildActionOnly] attribute has. However, in most examples, I kept asking myself why I'd create a new action method just to render a partial view, within another view, when you could simply render #Html.Partial("_MyParialView") directly in the view. It seemed like an unnecessary layer. However, as I investigated, I found that one benefit is that the child action can create a different model and pass that to the partial view. The model needed for the partial might not be available in the model of the view in which the partial view is being rendered. Instead of modifying the model structure to get the necessary objects/properties there just to render the partial view, you can call the child action and have the action method take care of creating the model needed for the partial view.
This can come in handy, for example, in _Layout.cshtml. If you have a few properties common to all pages, one way to accomplish this is use a base view model and have all other view models inherit from it. Then, the _Layout can use the base view model and the common properties. The downside (which is subjective) is that all view models must inherit from the base view model to guarantee that those common properties are always available. The alternative is to render #Html.Action in those common places. The action method would create a separate model needed for the partial view common to all pages, which would not impact the model for the "main" view. In this alternative, the _Layout page need not have a model. It follows that all other view models need not inherit from any base view model.
I'm sure there are other reasons to use the [ChildActionOnly] attribute, but this seems like a good one to me, so I thought I'd share.
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.TempValue = "Index Action called at HomeController";
return View();
}
[ChildActionOnly]
public ActionResult ChildAction(string param)
{
ViewBag.Message = "Child Action called. " + param;
return View();
}
}
The code is initially invoking an Index action that in turn returns two Index views and at the View level it calls the ChildAction named “ChildAction”.
#{
ViewBag.Title = "Index";
}
<h2>
Index
</h2>
<!DOCTYPE html>
<html>
<head>
<title>Error</title>
</head>
<body>
<ul>
<li>
#ViewBag.TempValue
</li>
<li>#ViewBag.OnExceptionError</li>
#*<li>#{Html.RenderAction("ChildAction", new { param = "first" });}</li>#**#
#Html.Action("ChildAction", "Home", new { param = "first" })
</ul>
</body>
</html>
Copy and paste the code to see the result .thanks

Client Side Validation fails when moving to viewmodel

This seems to a common question for lots of reasons that do not seem to apply to this situation. I have create page using ASP.NET MVC 2 and I was using a strongly typed view to a class generated from DataEnities framework.
<%# Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MVC_EDI.Models.wysCustomerEndPoint>"" %>
I made validation class that I bound back to the the data class.
[MetadataType(typeof(EndPointValidation))]
public partial class wysCustomerEndPoint
{
}
[Bind()]
public class EndPointValidation
{
[Required(ErrorMessage = "Please enter the end point name")]
public string CustName { get; set; }
And I was able to use client side validation on my create page. I had a requirement to add a dropdown list box on the create page, so I switched my view to use a viewmodel instead of the data class I was using.
public class CreateEditCustomerEndPointsViewModel
{
public wysCustomerEndPoint CustomerEndPoint {get; set;}
public List<SelectListItem> DefaultLocationList { get; set; }
}
and here is the view header using the new viewmodel.
<%# Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MVC_EDI.ViewModles.CreateEditCustomerEndPointsViewModel>" %>
But now when this view gets loaded I am getting an error that my formElement is null when it tries to set a value ? I error out here inteh MicrosofyMvcValidation.js file and the formElement array is null.
formElement['__MVC_FormValidation'] = this
I suspect I need to add some sort of data annotation or attribute to either my view model or something like that. But I am not sure where? And surprisingly it seems to work out just fine in FireFox 5 but bombs in IE9?
Edit: thanks for the reply. Yes I believe I am instantiating the object before adding to the ViewModel and using the Html.Helper objects? Here is the code.
wysCustomerEndPoint ep = new wysCustomerEndPoint();
ep.BuyerID = id;
var viewModel = new CreateEditCustomerEndPointsViewModel()
{
CustomerEndPoint = ep
};
return View(viewModel);
and in the view
<div class="editor-label">
<%: Html.Label("Name") %>
</div>
<div class="editor-field">
<%: Html.TextBoxFor(model => model.CustomerEndPoint.CustName) %>
<%: Html.ValidationMessageFor(model => model.CustomerEndPoint.CustName) %>
</div>
cheers
bob
You're maybe doing this, but without seeing the relevant bits of code I don't want to assume. So, make sure you are instantiating the wysCustomerEndPoint object and sending to your view from the Controller method. Also that you are using the Html Helpers for the input elements that you are validating on. Eg.
Html.TextboxFor(model => model.wysCustomerEndPoint.CustName)

Best Practice for Summary Footer (and the like) in MVC

Simple question on best practice. Say I have:
public class Product
{
public string Name { get; set; }
public string Price { get; set; }
public int CategoryID { get; set; }
public bool IsAvailable { get; set; }
}
and i have a view using IEnumerable< Product> as the model, and i iterate through the Products on the page and want to show the total of the prices at the end of the list, should I use:
<%= Model.Sum(x=> x.Price) %>
or should I use some other method? This may extend to include more involved things like:
<%= Model.Where(x=> x.CategoryID == 5 && x.IsAvailable).Sum(x=> x.Price) %>
and even
<% foreach (Product p in Model.Where(x=> x.IsAvailable) {%>
-- insert html --
<% } %>
<% foreach (Product p in Model.Where(x=> !x.IsAvailable) {%>
-- insert html --
<% } %>
I guess this comes down to should I have that sort of code within my view, or should i be passing it to my view in ViewData? Or perhaps some other way?
If the logic you are using on the page is related to the display of data on the page, then I don't have a problem using logic that does calculations. Calculating the values in your controller and supplying it as part of the model would couple the display to the action performed by the controller, i.e., if you simply want to change how the data is displayed -- for example, group by category and show sub-totals -- and expected all the data to be in the model, then you'd have to touch both the controller and the view to make the change. If you put the display-related calculations in the view, then only the view needs to change.
The call on whether the logic is business-related or view-related is heavily context dependent. For example, you might have a business rule that says you only display products that are available. Enforcing this rule certainly shouldn't be a function of the view so, in that case, you should move it into the controller (or even the model). But if it's a simple calculation of the contents of a shopping cart or filtering what you display based on model properties, I'd be ok with it in the view.
I would push this logic back into the controller and the "view model". I consider this to be the "model of the view". A simple example would be
return View(new ProductSummaryViewModel
{
Products = products,
TotalPrice = products.Sum(p => p.Price)
});
You can obviously extend this for whatever the view has to display. You can even have collections of sub-viewmodels which can make things a lot easier.
Hope this helps

ASP.NET MVC - MasterPageView and RenderPartials - Confusion

I'm a little confused with trying to do bring a list of Categories into a navigation bar on a MasterPageView in the latest release of the ASP.NET MVC framework.
I have 0 experience with Partials so far (this adds to the confusion).
Should I use this variant of the RenderPartial?
HtmlHelper.RenderPartial(string partialViewName, object model)
I wasn't able to find any good examples of this method. By convention there is no model associated with the MasterPageView right? So what is the proper way to push or pull data into a "partial" from the MasterPageView?
Assuming that this method is absolutely going down the wrong path:
<div id="navigation">
<%
CategoryRepository cr = new CategoryRepository();
IList<Category> lst = cr.GetCategories();
Html.RenderPartial("NavBar", lst);
%>
</div>
Do you not want your masterpage to have viewdata? You could solve it by having a base view data class that ALL your other viewdata classes inherit from...
BaseViewData.cs - this is a viewdata class that all other viewdata classes will inherit from
public class BaseViewData
{
public string Title { get; set; }
public string MetaKeywords { get; set; }
public string MetaDescription { get; set; }
IList<Category> NavCategoryList { get; set; }
}
Now in your Site.Master page simply have
<%# Master Language="C#" Inherits="System.Web.Mvc.ViewMasterPage<BaseViewData>" %>
<title><%=ViewData.Model.Title %></title>
<meta name="keywords" content="<%=ViewData.Model.MetaKeywords %>" />
<meta name="description" content="<%=ViewData.Model.MetaDescription %>" />
<%= Html.RenderPartial("NavBar", ViewData.Model.NavCategoryList) %>
This could significantly impact your application architecture, but its not necessarily a bad thing.
HTHs,
Charles
public ActionResult NavBar()
{
CategoryRepository cr = new CategoryRepository();
IList<Category> lst = cr.GetCategories();
return View(lst);
}
on your partial call
<%# Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %>
<%# Import Namespace="app.Models" %>
and do all your rendering ui here
<div id="navigation">
<%
Html.RenderPartial("NavBar");
%>
</div>
you can do ActionResult calls in your controllers
I would say that since it's the Master Page you would probably have to store your data that you are passing in ViewData with a string key. If it was a regular view page it would be better to have a strongly typed page, but this is a different case. So you would probably do something this in your controller:
ViewData["MasterPageData"] = FunctionToGetData();
And then on the Master Page something like this:
<%
if (ViewData["MasterPageData"] != null)
{
Html.RenderPartial("ControlName.ascx", ViewData);
}
%>
Then in the control, process like you would on a normal view page:
<% var categories = (CastIfNeeded)ViewData["MasterPageData"]; %>
process as normal...
I haven't had to pass data to a master page yet, but that's how I would think you'd do it. More info here.
EDIT: Changed it around a little to reflect what I'm doing in my current project.
I would use Html.RenderAction() instead and return a partial view from it.

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