I am trying to create a simple drop-down menu populating it with categories from a local database. I am using .NET Core 2.2. I am following a demo that uses an earlier version of ASP.NET MVC where they use ViewBag to transfer a list from the controller to view. For some reason, ViewBag doesn't work giving me a compiling error of "ViewBag does not exist in the current context". After a little bit of research, I opted to use ViewData which seems to work from the controller but I am having a little bit of trouble displaying the category Name from my model as when I run the page the drop-down options display "Model.Visportfolio.Category" rather than the category Name itself.
I am fairly new to HTML so I tried replicating the code from the demo but I am having trouble accessing the fields of my Category class. I tried using ViewBag as from my research, ViewData and ViewBag are "interchangeable" but no luck.
HTML for where I call my drop-down menu, code does not compile as it says CategoryName and CategoryId does not contain the definition and no accessible extension method
<form asp-controller="my_dropdown" asp-action="CreatePortfolio" method="post" class="form-horizontal" role="form">
<div class="form-group">
<div class="row">
<div class="alert-danger" asp-validation-summary="ModelOnly"></div>
<div class="col-xs-12 col-sm-6 col-md-6 col-lg-4">
<label asp-for="CategoryName" class="control-label"></label>
<select asp-for="CategoryId"
class="form-control"
asp-items="#(new SelectList(ViewBag.categorylist, "CategoryId", "CategoryName"))">
</select>
#Html.DropDownList("categorylist",
new SelectList((System.Collections.IEnumerable) ViewData["categorylist"]), "Select Category","CategoryName" )
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-xs-12 col-sm-6 col-lg-4">
<input id="Submit1" type="submit" value="submit" />
</div>
</div>
</div>
</form>
This is the code behind the html
public void OnGet()
{
// ----- Getting Data From Database Using EntityFrameworkCore ----
categorylist = (from category in _context.Category
select category).ToList();
// ----- Inserting Select Item in List -----
categorylist.Insert(0, new Category { CategoryId = 0, CategoryName = "Select" });
// ----- Assigning categorylist to ViewBag.ListOfCategory -----
// ViewBag.categortyList = categorylist;
ViewData["categorylist"] = categorylist;
}
Model
namespace Visportfolio.Models
{
[Table("Category")]
public class Category
{
[Key]
public int CategoryId { get; set; }
public string CategoryName { get; set; }
}
}
You are looking for
new SelectList(ViewData[categoryList], "Value", "Text")
SelectList has alot of overloads that you can use see here
So use
#Html.DropDownList("categorylist",
new SelectList((System.Collections.IEnumerable) ViewData["categorylist"], "CategoryId", "CategoryName"), "Select Category","CategoryName" )
Related
I want to call a specific Action with a parameter that corresponds to the the selected element in a tag.
The Model of the View can be simplified as follows:
public class Model
{
public string SelectedElement {get; set}
public List<SelectListItem> Elements { get; set; }
}
That i'm trying to display in the View:
<h2>Info</h2>
<div class="row">
<div class="form-group row">
<label for="selector-info" class="col-sm-2 col-form-label">Elements</label>
<div class="col-sm-10">
<select id="selector-info" asp-for="#Model.SelectedElement " asp-items="#Model.Elements">
</select>
</div>
</div>
</div>
<div class="row">
<a class="btn btn-primary"
asp-controller="Info"
asp-action="Export"
asp-route-element="#Model.SelectedElement ">
Exportar
</a>
</div>
And the action in the controller:
[Route("export/{element}")]
public async Task<IActionResult> Export(string element)
{
// Do something with the data
return RedirectToAction("Info");
}
Here what I'm trying to do is to call this specific Action that accepts a parameter, and fill it with the selcted element in the tag
But the generated HTML href was incorrect, and debugging I found out that the value Model.SelectedElement was not beeing set correctly.
On the other hand if I wrap this code inside a form and change the link to a button it works. My problem with this is that I'll have multiple buttons (at least 2) that will do different actions but in all cases the selected value of the tag must be passed when the button is clicked.
Is there a way to achieve this? I know I can get the value through JavaScript but I'm trying to find a way to do this directly in ASP without JS.
Here is the context :
This is my first ASP.NET MVC web application.
On the categories list, I click on a category to see all infos about it in a new view.
From this view, I display its name, its description and the number of products in this category.
Below that, I want to display all products in this category.
I gave a try to the Html.Action() method.
But when I want to iterate through the foreach statement, Visual Studio tells me that Type 'System.Web.Mvc.MvcHtmlString' is not enumerable.
Here is my view (details about a category):
#model UlysseCMS.Models.category
#{
ViewBag.Title = "Details about "+ Model.category_name + " category";
var nbProducts = Html.Action("GetNumberOfProductByCategory", "Product", Model.category_id);
var productsList = Html.Action("GetListOfProductsByCategory", "Product", Model.category_id);
}
<div>
<span class="leader">
<span class="mif-chevron-thin-right fg-teal"></span>
<span>#Html.ActionLink("Categories", "Index")</span>
<span class="mif-chevron-thin-right fg-teal"></span>
<span>#Model.category_name</span>
<span class="mif-chevron-right fg-teal"></span>
<span>details</span>
</span>
</div>
<br />
<hr class="bg-teal" />
<br />
<div class="margin30">
<div class="flex-grid">
<div class="row cells7">
<div class="cell colspan3 offset1 sub-header">
Category name :
</div>
<div class="cell colspan4">
#Model.category_name
</div>
</div> <br/>
<div class="row cells7">
<div class="cell colspan3 offset1 sub-header">
Category description :
</div> <br/>
<div class="cell colspan4">
#Model.category_description
</div>
</div> <br/>
<div class="row cells7">
<div class="cell colspan3 offset1 sub-header">
Number of products in this category :
</div>
<div class="cell colspan4">
#nbProducts
</div>
</div>
</div>
</div>
#foreach (var item in productsList)
{
}
Here is my GetListOfProductsByCategory() method from the ProductController :
public IEnumerable<product> GetListOfProductsByCategory(int id)
{
return db.product.Where(x => x.product_category_id == id);
}
I still continue to find a solution with IEnumerable casting or something.
Thanks,
Hellcat.
The result of #Html.Action is a View.
When you have an action inside a controller, this action usually return a view, and that rendered view is result of Html.Action ,for displaying it you need to use an # before html.
You should write your code as below:
public ActionResult GetListOfProductsByCategory(int id)
{
return View(db.product.Where(x => x.product_category_id == id));
}
Then right click on View and from menu select Add View, then create a partial view.
inside partial view you can enumerate your list and create the rendered out put.
Finally wherever you want to show the rendered list, just call:
#Html.Action("GetListOfProductsByCategory",id)
When creating view, you need to select your model and view type as list so on top of your view you would have:
#model IEnumerable<product>
Then you must use you foreach as below:
#foreach (var item in Model)
{
}
Okay I modified my Partial View (GetListOfProductsByCategory) like that :
#model IEnumerable<UlysseCMS.Models.product>
#foreach (var item in Model)
{
<a href="#Url.Action("Details", new { id = item.product_id })">
<div class="tile tile-wide bg-white block-shadow margin30" data-role="tile">
<div class="tile-content slide-up-2">
<div class="slide fg-darkTeal">
<span class="sub-leader" style="padding-left: 5px;">#Html.DisplayFor(modelItem => item.product_name)</span>
</div>
</div>
</div>
</a>
}
And in my Category Details View I display the products like this :
#Html.Action("GetListOfProductsByCategory", "Product", Model.category_id)
It's now okay hanks to Mehrdad Babaki's answer.
I have a parameterless Index for the HttpGet which works. But when I post it the HttpPost version of Index is invoked and the viewmodel object is passed in, but there is only the value of the dropdown in it. The rest is null (products, title)
[HttpPost]
public ActionResult Index(ProductsViewModel pvm)
{
// breakpoint on line 36, shows that pvm.Title is null and Products too.
return View(pvm);
}
My compilable and running example can be downloaded from my OneDrive http://1drv.ms/1zSsMkr
My view:
#model KleinKloteProductOverzicht.Models.ProductsViewModel
#using (Html.BeginForm("Index", "Products"))
{
<h2>#Html.DisplayFor(m => m.Title)</h2>
<input type="submit" value="post dit" /><br/>
<div class="row">
<div class="col-lg-2 col-md-2">
#Html.DropDownListFor(x => x.CurrentSort, EnumHelper.GetSelectList(typeof(SortOptions)), new { #class = "multiselect"})
</div>
</div>
if (Model.Products.Count() > 0)
{
<div class="row">
#foreach (var item in Model.Products)
{
#Html.DisplayFor(i => item.Name);
}
</div>
}
}
If I have this view model:
public class ViewModel
{
public string Name {get;set;}
public string SelectedLocation {get;set;}
public IEnumerable<SelectListItem> Locations {get;set;}
}
And your actions look like this:
public ActionResult MyForm()
{
var vm = new ViewModel
{
Locations = context.Locations.ToList() // Some database call
}
return View(vm);
}
[HttpPost]
public ActionResult MyForm(ViewModel vm)
{
vm.Locations // this is null
}
It is null because the model binder can't find a form control that is setting its data.
The <form> must set some data in the view for the model binder to pick it up.
<form>
Name: <input type="text" id="name" />
</form>
This will set the Name property on the view model, because the model bind can see the id of the form control and uses that to know what to bind to.
So in terms of your view, you need to make sure you wrap any content that you want to post back to the server with #using(Html.BeginForm())
Anyway this is my guess.
Well, you seem to be confused as to how [HttpPost] and form tags interact with eachother.
You see, when .NET MVC binds your parameters in your controller actions, it tries to derive that data from the request. For [HttpGet] it does this by looking at the query string.
For [HttpPost] calls, it also looks at the Request.Form. This variable is populated with the values of all input fields that were inside the form you submitted.
Now, this is your view:
#using (Html.BeginForm("Index", "Products"))
{
<h2>#Html.DisplayFor(m => m.Title)</h2>
<input type="submit" value="post dit" /><br/>
<div class="row">
<div class="col-lg-2 col-md-2">
#Html.DropDownListFor(x => x.CurrentSort, EnumHelper.GetSelectList(typeof(SortOptions)), new { #class = "multiselect" })
</div>
</div>
if (Model.Products.Count() > 0)
{
<div class="row">
#foreach (var item in Model.Products)
{
#Html.DisplayFor(i => item.Name);
}
</div>
}
}
You only have one select tag (generated by Dropdownlistfor) but no other inputs. That's why .NET MVC cannot infer any other data for your view model.
If you change your view to this:
#model KleinKloteProductOverzicht.Models.ProductsViewModel
#using (Html.BeginForm("Index", "Products"))
{
<h2>#Html.DisplayFor(m => m.Title)</h2>
<input type="submit" value="post dit" /><br/>
<div class="row">
<div class="col-lg-2 col-md-2">
#Html.DropDownListFor(x => x.CurrentSort, EnumHelper.GetSelectList(typeof(SortOptions)), new { #class = "multiselect" })
</div>
</div>
if (Model.Products.Count() > 0)
{
<div class="row">
#for (var i = 0; i < Model.Products.Count; i++)
{
#Html.DisplayFor(model => model.Products[i].Name)
#Html.HiddenFor(model => model.Products[i].ID)
}
</div>
}
}
You'll see I've added a hidden input (<input type="hidden">) for the product id. Note that the product name still will be null.
I would suggest you follow a tutorial on .NET MVC and read up on some of the concepts behind it, because the very fact that you ask this question reveals that you have much to learn.
Best of luck!
P.S. One last tip: #Html.Blablabla writes directly to your view. You usually don't need that ";" at the end, because it will be inside your generated html.
Your property is not associated with a "postable" control, therefore it will not be submitted along with the form data. If your really want to get the value in your Title property, just set it as a hidden input.
#Html.HiddenFor(m => m.Title)
A label will not be posted when submitting a form but an input will. This is exactly what HiddenFor does; it creates a hidden input element which will be picked up by the form submit.
I'm writing an MVC app which ends up accessing a SQL database. On my edit page, I previously had every item available to be edited that is in the model. Recently I was asked to no longer allow the user to edit the primary keys. I did a quick change to change the primary key fields (in this example, there are 2 of them) from an EditorFor to a DisplayFor. The new view is this:
#model App.Data.Item
#{
ViewBag.Title = "Edit";
}
<h2>Edit</h2>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>Item</h4>
<hr />
#Html.ValidationSummary(true)
<div class="form-group">
<strong>ID:</strong>
<div class="col-md-10">
<p>#Html.DisplayFor(model => model.ID)</p>
</div>
</div>
<div class="form-group">
<strong>ID2:</strong>
<div class="col-md-10">
<p>#Html.DisplayFor(model => model.ID2)</p>
</div>
</div>
<div class="form-group">
<strong>Description:</strong>
<div class="col-md-10">
<p>#Html.EditorFor(model => model.Description)
#Html.ValidationMessageFor(model => model.Description)</p>
</div>
</div>
<br />
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<button type="submit" class="btn btn-primary">Submit <i class="fa fa-caret-right"></i></button>
</div>
</div>
</div>
}
It used to work with the full editing. Now the data is displayed properly, as expected. However, when submit is pressed, Null values are passed back to the controller for the values that are displayed.
These are the edit functions in my controller. ItemService.Edit() just saves the data to the server. It works correctly.
[Authorize]
public ActionResult Edit(string id)
{
if (id == null)
{
//return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
string[] vals = id.Split('|');
ItemAttribute itemAttribute = itemAttributeService.Find(int.Parse(vals[0]), vals[1]);
if (itemAttribute == null)
{
return HttpNotFound();
}
return View(itemAttribute);
}
[HttpPost]
[ValidateAntiForgeryToken]
[Authorize]
public ActionResult Edit([Bind(Include = "ID,ID2,Description")]
Item item)
{
if (item.Description == null)
{
ModelState.AddModelError("Description", "Description cannot be null.");
}
if (ModelState.IsValid)
{
itemService.Edit(item);
return RedirectToAction("../Home/Index/");
}
return View(item);
}
Lastly, my data model:
public class Item
{
public int ID { get; set; }
public string ID2 { get; set; }
public string Description { get; set; }
}
Why is the data no longer being passed back to the second function, and how do I get it to pass correctly so that I can save it to the database?
You need to have an input element generated for the items that you want returned. Currently, you are only displaying two of your model elements and have no associated input with them. As a result, they will not be POSTed back to the server.
To get them to post to the server and not "editable" from a textbox, add a Html.HiddenFor() helper for each of the items that you need returned.
<div class="form-group">
<strong>ID:</strong>
<div class="col-md-10">
<p>#Html.DisplayFor(model => model.ID)</p>
<p>#Html.HiddenFor(model => model.ID)</p>
</div>
</div>
<div class="form-group">
<strong>ID2:</strong>
<div class="col-md-10">
<p>#Html.DisplayFor(model => model.ID2)</p>
<p>#Html.HiddenFor(model => model.ID)</p>
</div>
</div>
However, keep in mind that anyone can edit the HTML using Firebug or Chrome console tools and submit any value that they want for any field, even if you did not want to change it. Be sure that when you are persisting the changes to the database, you are NOT including these fields as part of the update.
Try this, just before this line of code:
#Html.DisplayFor(model => model.ID)
put in this for debugging:
#Html.LabelFor(model => model.ID)
Tell us what you see...
If you see the label then check your controller, in particular the parameter it takes on the post. It should take and Item of type ITEM per your model.
Before the controller receives the data MVC has to try to populate the data... It converts name/value pairs to model types with values secretly. If you don't see any data after you are in the controller it's usually because the names were not found!
I have asp.net MVC application which can retrieve data from database. It looks like this:
If my url is like this:
myurl.com/Home/Index/1
my view is like this: [https:// scontent-b-fra.xx.fbcdn.net/hphotos-xfp1/t31.0-8/10571949_782177481813619_1929089026797570629_o.jpg][1]
if url is like this :-
myurl.com/Home/Index/2
view is like this: https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-xpa1/t31.0-8/10519689_782177478480286_8967524557745769669_o.jpg
etc..
I'm passing and in url which is the id of data in my database :-
public ActionResult Index(int id)
{
BIOEntities db = new BIOEntities();
AddBio bio = new AddBio();
Biography biography = db.Biographies.Where(x => x.Id == id).FirstOrDefault();
bio.Id = biography.Id;
bio.Photo = biography.Photo;
bio.Name = biography.Name;
bio.Position = biography.Position;
return View(bio);
}
Now i want to make that if my url will
myurl.com/Home/Index
It must retrieve data like this: https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpa1/t31.0-8/10454247_782178191813548_1334099737795866885_o.jpg
anyone please explain me how can I do that
[1]: https://%20scontent-b-fra.xx.fbcdn.net/hphotos-xfp1/t31.0-8/10571949_782177481813619_1929089026797570629_o.jpg
and there's my view (Customhelper is for pictures..) :
#model BioMVC.Models.AddBio
#using BioMVC.CustomHtmlHelpers
#{
ViewBag.Title = "Index";
Layout = "~/Views/_layout.cshtml";
}
<div id="first">
<div class="display-field">
#Html.Image(#Model.Photo, new { #id = "FirstPhoto" })
</div>
<legend class="orangeText">#Model.Name</legend>
<legend class="orangeText">#Model.Position</legend>
</div>
<div id="second">
<div class="display-field">
#Html.Image(#Model.Photo, new { #id = "secondPhoto" })
</div>
<legend class="orangeText">#Model.Name</legend>
<legend class="orangeText">#Model.Position</legend>
</div>
<div id="third">
<div class="display-field">
#Html.Image(#Model.Photo, new { #id = "thirdPhoto" })
</div>
<legend class="orangeText">#Model.Name</legend>
<legend class="orangeText">#Model.Position</legend>
</div>
<div id="fourth">
<div class="display-field">
#Html.Image(#Model.Photo, new { #id = "fourthPhoto" })
</div>
<legend class="orangeText">#Model.Name</legend>
<legend class="orangeText">#Model.Position</legend>
</div>
george,
without seeing your current view code, i am assuming that it is something along the lines of:
#model yournamespace.models.AddBio
this will therefore only show a SINGLE instance as per the code in the current index action method. What you need to do is to make that model a List<AddBio> along the lines of:
#model List<yournamespace.models.AddBio>
you can then iterate round the list to populate as you had been before. You will also need to change your index method to reference a List<>, rather than a single entity (hint: removing the .FirstOrDefault() on the 3rd line is your starting point - the rest is all just common sense in passing back the List<> rather than a single instance).
hope this helps..
[edit] - as per stephen muecke's response, you should also test for nullable id -good point!!