I have a FK in my Details ViewModel and when the View binds to the ViewModel I only get the FK back (expected). The FK is a reference to a simple ID/Name type table. I also have a Strongly typed List in the VM representing that FK-referenced table. I want to do something like
<div class="display-field">#Model.ManufacturersList.Find(x => x.ID == Model.softwaremanufacturerid))</div>
While this will return the the instance I want...I can't figure out how to get the "Name" attribute to display.
Sorry if this is more a Lamda question but thought I'd try all the same
Thanks
If .ManufacturersList.Find(x => x.ID == Model.softwaremanufacturerid) returns what you want, don't do it in the View. The View should only display data, while the model layer should really be doing the searching (.Find)
In your view model, add a string property for ManufacturerName
public string ManufacturerName { get; set; }
In your controller,
MyViewModel vm = new MyViewModel()
{
ManufacturerName = .ManufacturersList
.Find(x => x.ID == theFKAlreadyInTheViewModel)
};
return View(vm);
Then in your view,
#Model.ManufacturerName
OR, more simply, you could use the ViewBag
ViewBag.ManufacturerName = YourManufacturersList
.Find(x => x.ID == theFKAlreadyInTheViewModel);
Then in your View,
#ViewBag.ManufacturerName
Related
I am having a problem passing to the View a Model that contains the dropdown data and the model.
With this code my page loads, but the dropdownlist contains "System.Web.MVC.SelectList" when selected.
Here's my controller code.
public ActionResult Index(string productNameFilter, string productCategoryFilter, String productTypeFilter )
{
var ddl = new Items();
ddl.CategoryddList = itemsRepository.GetItemDdl("Item Categories").Select(c => new SelectListItem
{
Value = c.DropdownID.ToString(),
Text = c.DropdownText
});
ViewBag.CategoryDD = new SelectList(ddl.CategoryddList, "Value", "Text");
var model = itemsRepository.GetItemByName(productNameFilter);
return View(model);
}
Here's my view
#model Ienumerable<Models.items.items>
#Html.DropDownList("productCategoryFilter",
new SelectList(ViewBag.CategoryDD),
"---Select Category---")
Side note - if you use a ViewModel between the View and the Model instead of binding directly to the model, you can put your SelectList on the ViewModel and use #Html.DropdownFor() instead of #Html.Dropdown(). The ViewBag should really be used sparingly.
However back to your original question:
What is "Items()"? in your line
var ddl = new Items();
I'm not sure what good reason you would have NOT to make it enumerable.
I suspect it is not working because you are making a selectlist from a select list twice --
in your code behind you are defining ViewBag.CategoryDD as a SelectList(), and then in your Razor code you are creating a new SelectList() from the existing selectlist. You shouldn't have to do this.
The way I would do this is create a ProductViewModel class that contains your product category list AND your list of products (your current model), and a property for the selected filter.
public class ProductViewModel
{
public IEnumerable<Model.items.items> ProductList {get;set;}
public IEnumerable<SelectListItem> ProductCategoryList {get;set;} //SelectList is an IEnumerable<SelectListItem>
public string SelectedCategory {get;set;}
}
Then on your view the model would be
#model ProductViewModel
#Html.DisplayFor(model => model.SelectedCategory, "---Select Category---")
#Html.DropdownListFor(model => model.SelectedCategory, Model.ProductCatgoryList)
I have a controller that is building a query from Linq to Sql to pass into the ViewBag.products object. The problem is, I cannot loop using a foreach on it as I expected I could.
Here's the code in the controller building the query, with the .ToList() function applied.
var products = from bundles in db.Bundle
join bProducts in db.BundleProducts on bundles.bundleId equals bProducts.bundleID
join product in db.Products on bProducts.productID equals product.productID
join images in db.Images on product.productID equals images.productID
where bundles.bundleInactiveDate > DateTime.Now
select new {
product.productName,
product.productExcerpt,
images.imageID,
images.imageURL
};
ViewBag.products = products.ToList();
Since I am using a different model on the Index.cshtml for other items needed, I thought a simple Html.Partial could be used to include the viewbag loop. I have tried it with the same result with and without using the partial and simply by using the foreach in the index.cshtml. A snippet that includes the partial is below:
<div id="bundle_products">
<!--build out individual product icons/descriptions here--->
#Html.Partial("_homeBundle")
</div>
In my _homeBundle.cshtml file I have the following:
#foreach (var item in ViewBag.products)
{
#item
}
I am getting the ViewBag data, but I am getting the entire list as output as such:
{ productName = Awesomenes Game, productExcerpt = <b>Awesome game dude!</b>, imageID = 13, imageURL = HotWallpapers.me - 008.jpg }{ productName = RPG Strategy Game, productExcerpt = <i>Test product excerpt</i>, imageID = 14, imageURL = HotWallpapers.me - 014.jpg }
What I thought I could do was:
#foreach(var item in ViewBag.Products)
{
#item.productName
}
As you can see, in the output, productName = Awesomenes Game. However, I get the error 'object' does not contain a definition for 'productName' when I attempt this.
How can I output each "field" so to say individually in my loop so I can apply the proper HTML tags and styling necessary for my page?
Do I need to make a whole new ViewModel to do this, and then create a display template as referenced here: 'object' does not contain a definition for 'X'
Or can I do what I am attempting here?
*****UPDATE*****
In my Controller I now have the following:
var bundle = db.Bundle.Where(a => a.bundleInactiveDate > DateTime.Now);
var products = from bundles in db.Bundle
join bProducts in db.BundleProducts on bundles.bundleId equals bProducts.bundleID
join product in db.Products on bProducts.productID equals product.productID
join images in db.Images on product.productID equals images.productID
where bundles.bundleInactiveDate > DateTime.Now
select new {
product.productName,
product.productExcerpt,
images.imageID,
images.imageURL
};
var bundleContainer = new FullBundleModel();
bundleContainer.bundleItems = bundle;
return View(bundleContainer);
I have a model, FullBundleModel
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace JustBundleIt.Models
{
public class FullBundleModel
{
public IQueryable<Bundles> bundleItems { get; set; }
public IQueryable<Images> imageItems { get; set; }
}
}
and my View now has
#model IEnumerable<JustBundleIt.Models.FullBundleModel>
#foreach (var item in Model)
{
<div class="hp_bundle">
<h3>#Html.Display(item.bundleName)</h3>
</div>
}
If I remove IEnumerable from the model reference, the foreach errors out that there is no public definition for an enumerator.
In the #Html.Display(item.bundleName) it errors out that the model has no definition for bundleName. If I attempt
#foreach(var item in Model.bundleItems)
I get an error that bundleItems is not defined in the model.
So what don't I have wired up correctly to use the combined model?
Do I need to make a whole new ViewModel to do this, and then create a
display template as referenced here...
Darin's answer that you linked states the important concept: Anonymous types are not intended for use across assembly boundaries and unavailable to Razor. I would add that it's rarely a good idea to expose anonymous objects outside of their immediate context.
Creating a view model specifically for view consumption is almost always the correct approach. View models can be reused across views if you are presenting similar data.
It's not necessary to create a display template, but it can be useful if you want to reuse the display logic. HTML helpers can also fill a similar function of providing reusable display logic.
Having said all of that, it's not impossible to pass an anonymous type to a view, or to read an anonymous type's members. A RouteValueDictionary can take an anonymous type (even across assemblies) and read its properties. Reflection makes it possible to read the members regardless of visibility. While this has its uses, passing data to a View is not one of them.
More reading:
Can I pass an anonymous type to my ASP.NET MVC view?
Dynamic Anonymous type in Razor causes RuntimeBinderException
Why not create a new model that contains all of the data that you need?
Example One:
public class ContainerModel
{
public IQueryable<T> modelOne;
public IQueryable<T> modelTwo;
}
This will allow you to access either of your queries in Razor:
#model SomeNamespace.ContainerModel
#foreach (var item in Model.modelOne)
{
//Do stuff
}
I personally avoid using ViewBag at all and store everything I need in such models because it's NOT dynamic and forces everything to be strongly typed. I also believe that this gives you a clearly defined structure/intent.
And just for clarity's sake:
public ViewResult Index()
{
var queryOne = from p in db.tableOne
select p;
var queryTwo = from p in db.tableTwo
select p;
var containerModel = new ContainerModel();
containerModel.modelOne = queryOne;
containerModel.modelTwo = queryTwo;
return View(containerModel);
}
Example Two:
public class ContainerModel
{
[DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}")] //Format: MM/dd/yyyy (Date)
public Nullable<DateTime> startDate { get; set; }
[DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}")] //Format: MM/dd/yyyy (Date)
public Nullable<DateTime> endDate { get; set; }
public SelectList dropdown { get; set; }
public IQueryable<T> modelOne { get; set; }
public IQueryable<T> modelTwo { get; set; }
}
In this case you've stored 3 other items in the model with your 2 queries. You can use the Html helpers to create a Drop Down List in Razor:
#Html.DropDownList("dropdown", Model.dropdown)
And you can use the DisplayFor helper to display your dates as defined in your model with Data Annotations:
#Html.DisplayFor(a => a.startDate)
This is advantageous IMO because it allows you to define all of the data that you want to make use of in your View AND how you plan to format that data in a single place. Your Controller contains all of the business logic, your Model contains all of the data/formatting, and your View is only concerned with the content of your page.
working with MVC 3.
I have a dropdownlist which populates Gender with value 'M' for text 'Male' and 'F' for text 'Female'.
Now, when I extract record it is not setting the value as per the record's value.
I have following on code in view.
#if(Model != null)
{
#Html.DropDownListFor(model => model.GENDER,
new SelectList(ViewBag.gender, "Value", "key", Model.GENDER))
}
else
{
#Html.DropDownListFor(model => model.GENDER,
new SelectList(ViewBag.gender, "Value", "Key"))
}
The above code means that when page first loads it has no value for gender field as model is empty so just populate list and when person is extracted i.e. when model is not null it populates and set value equal to model.gender. But it is not setting the value. What could be the problem?
Are you passing an NULL object (your model) to your view ? How many places in the view are you going to write #if(Model != null).. . Is that not going to mess up the concept of Clean code. ?
I guess this is how you should do it. You should always pass the model/ Viewmodel to the view no matter it is the firs time (Create Entity) or the Editing time. Some thing like this
public ActionResult Create()
{
CustomerViewModel model=new CustomerViewModel();
return View(model);
}
For Edit action, You fill the Model/ViewModel object filled with data.
public ActionResult Edit(int id)
{
CustomerViewModel model=new CustomerViewModel();
model=CustomerService.GetCustomerFromId(id);
return View(model);
}
and in the View, you use it like this
#model CustomerViewModel
#Html.DropDownListFor(model => model.GENDER,
new SelectList(ViewBag.gender, "Value", "key", Model.GENDER))
So, I am implementing ASP Membership and Role management in my application. I also have a second User table with all non-membership related information. I set the E-mail as the username in Membership and as the foreign key in my User table.
I am customizing the registration page to include a dropdown so a manager can be selected when the account is created. The list of managers is generated by finding all Membership users with the role "Manager" then creating a collection of Users where the foreign keys match the results.
List<string> managerNames = new List<string>(Roles.GetUsersInRole("Manager"));
var managers = from m in _db.Users where managerNames.Contains(m.Email) select m;
ViewBag.managers = managers;
Now I have to use that collection of users to populate a dropdown in my view that has the Name attribute set to "ManagerID" (to match my RegistrationModel), the value of each option set to the primary key of the User, and the displayed text in the dropdown showing the DisplayName of the User model.
I can go through the tedious task of looping through my "managers" collection and populating a separate SelectListItem, then passing the SelectListItem into a #Html.DropDown("ManagerID", newSelectListItem), but that seems excessive. Is there a more direct (or acceptable) way to do this?
EDIT
I added this to my controller
var selectList = new List<SelectListItem>();
foreach (var manager in managers)
{
selectList.Add(new SelectListItem(){
Value = manager.UserID.ToString(),
Text = manager.DisplayName,
Selected = false
});
}
ViewBag.managers = selectList;
and this to my view
#Html.DropDownList("ManagerID", (List<SelectListItem>)ViewBag.managers)
and it works. Is this still the best approach?
Is this still the best approach?
No. The best approach is to use view models and forget about the existence of ViewBag/ViewData. So start by designing a view model which will meet the requirements of your view (display a ddl of managers):
public class MyViewModel
{
[Required]
public int? SelectedManagerId { get; set; }
public IEnumerable<SelectListItem> Managers { get; set; }
}
and then have your controller action populate this view model and pass it to the view:
public ActionResult Foo()
{
var managers = ... query your repository to get them
var model = new MyViewModel
{
Managers = managers.Select(x => new SelectListItem
{
Value = x.UserID.ToString(),
Text = x.DisplayName
})
};
return View(model);
}
and finally in your strongly typed view:
#model MyViewModel
...
#Html.DropDownListFor(
x => x.SelectedManagerId,
Model.Managers,
"-- Select a manager --"
)
So everytime you employ ViewBag/ViewData in an ASP.NET MVC applications an alarm should ring telling you that there is a better way.
I'm running into an issue trying to use #Html.DropDownListFor().
I have a model with a navigation property on it:
public class Thing {
...
public virtual Vendor Vendor { get; set; }
}
In the controller I'm grabbing the vendor list to throw into the ViewBag:
public ActionResult Create() {
ViewBag.Vendors = Vendor.GetVendors(SessionHelper.CurrentUser.Unit_Id);
return View();
}
The html item in the view looks like this:
#Html.DropDownListFor(model => model.Vendor, new SelectList(ViewBag.Vendors, "Id", "Name"), "---- Select vendor ----")
#Html.ValidationMessageFor(model => model.Vendor)
The dropdown list is being rendered, and everything seems fine until I submit the form. The HttpPost Create method is returning false on the ModelState.IsValid and throwing a Model Error: The parameter conversion from type 'System.String' to type '...Models.Vendor' failed because no type converter can convert between these types.
If I let the page post through, I end up with a server error:
Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: items
After searching high and low I haven't been able to find a reason that the #Html.DropDownListFor() isn't properly auto-binding a Vendor object to the navigation property.
Any help would be greatly appreciated.
EDIT:
I ended up having to explicitly set the ForeignKey attributes so that I could directly access "Vendor_Id" then I changed the DropDownListFor to point to "Vendor_Id" instead of the navigation property. That seems to work.
I have found that the best way to do this is as follows. Change the controller to create the SelectListItems.
public ActionResult Create() {
ViewBag.Vendors = Vendor.GetVendors(SessionHelper.CurrentUser.Unit_Id)
.Select(option => new SelectListItem
{
Text = (option == null ? "None" : option.Name),
Value = option.Id.ToString()
});
return View();
}
Then modify the view as follows:
#Html.DropDownListFor(model => model.Vendor, (IEnumerable<SelectListItem>)ViewBag.Vendors, "---- Select vendor ----")
#Html.ValidationMessageFor(model => model.Vendor)
You have to cast the ViewBag.Vendors as (IEnumerable).
This keeps the views nice and neat. You could also move the code that gets the SelectListItems to your repo and put it in a method called something like GetVendorsList().
public IEnumerable<SelectListItem> GetVendorsList(int unitId){
return Vendor.GetVendors(unitId)
.Select(option => new SelectListItem
{
Text = (option == null ? "None" : option.Name),
Value = option.Id.ToString()
});
}
This would separate concerns nicely and keep your controller tidy.
Good luck
I have replied similar question in following stackoverflow question. The answer is good for this question too.
Validation for Navigation Properties in MVC (4) and EF (4)
This approach doesn't publish the SelectList in controller. I don't think publishing SelectList in controller is good idea, because this means we are taking care of view part in controller, which is clearly not the separation of concerns.