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How to automatically add a name from selected id in View page from controller ASP.NET MVC

I want to get a name from selected id in my view page
First Model
public class Transaction
{
[Key]
public int Id { get; set; }
[Required]
public int supplier_id { get; set; }
[Required]
public string supplier_name { get; set; }
}
Second Model
public class Supplier
{
[Key]
public int supplier_id { get; set; }
[Required]
public string supplier_name { get; set; }
}
View Model
public class EvaluateSheet
{
public IEnumerable<Supplier> Suppliers{ get; set; }
public IEnumerable<Transaction> Transactions { get; set; }
public Transaction Transaction { get; set; }
}
Controller
public IActionResult Sheet11()
{
var sup = _db.Supplier.ToList();
ViewBag.Sup = new SelectList(sup, "supplier_id", "supplier_name");
return View();
}
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Sheet11(EvaluateSheet objc)
{
Transaction Model = objc.Transaction;
Transaction transaction = new Transaction();
transaction.Id = Model.Id;
transaction.supplier_id = Model.supplier_id;
transaction.supplier_name = Model.supplier_name;
_db.Transaction.Add(Model);
Model.supplier_name = Model.Supplier.supplier_name.Where(Model.Supplier.supplier_id == Model.supplier_id);
_db.SaveChanges();
return RedirectToAction("Index");
}
View Page
#model EvaluateSheet
<form method="post">
<select asp-for="#Model.Transaction.supplier_id" asp-items="#ViewBag.Sup" value="#ViewBag.Sup" class="form-control">
<option selected disabled>--choose supplier--</option>
</select>
<button type="submit" class="btn btn-primary">Add Transaction</button>
I want to automatically insert supplier_name field after I selected supplier_id in my View page into the database.
I have tried this in my controller but it doesn't work
Model.supplier_name = Model.Supplier.supplier_name.Where(Model.Supplier.supplier_id == Model.supplier_id);

Try this:
Define an integer type variable in EvaluateSheet model for example("public int Sup_id { get; set; }") and tag it with DropDownListFor.
In Controller select specific data from supplier table with the help of new define int Sup_id and copy this data in Model(Transaction).
For example:
Transaction Model = new Transaction();
Supplier supl = null;
supl = _db.Supplier.Where(x => x.supplier_id == objc.Sup_id).FirstOrDefault();
Model.supplier_id = supl.supplier_id;
Model.supplier_name = supl.supplier_name;
_db.Transaction.Add(Model);
_db.SaveChanges();
return RedirectToAction("Index");

Retrieving data from a ViewModel in POST method

I have a View model that looks like this
public class ItemViewModel
{
[Required]
public int Id { get; set; }
public string ItemId { get; set; }
public string ItemName { get; set; }
public string MFGNumber { get; set; }
public IList<ItemPartViewModel> Parts { get; set; }
public IList<ItemComponentViewModel> Components{ get; set; }
public IList<ComponentPartViewModel> ComponentParts { get; set; }
public IList<ComponentSubCompViewModel> ComponentSubComps { get; set; }
public IList<SubCompPartViewModel> SubCompParts { get; set; }
public IList<SubCompSubCompViewModel> SubCompSubComps { get; set; }
public IList<SubCompSubCompPartViewModel> SubCompSubCompParts { get; set; }
}
As you can see the Viewmodel also has corresponding view models that look like this
public class ItemPartViewModel
{
[Required]
public int ID { get; set; }
public string PartID { get; set; }
public HtmlString PartLink { get; set; }
public string MFGNumber { get; set; }
public string PartName { get; set; }
public float QtyInItem { get; set; }
public float OnHand { get; set; }
public float OnWorkOrder { get; set; }
public float Committed { get; set; }
public float FSTK { get; set; }
// This is the additional property to contain what user picks
public PartActionType SelectedActionType { get; set; }
}
The ItemViewModel is populated through my OrderSelection GET method that looks like this
public ActionResult SpecialOrderSelection(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
JobOrder jobOrder = db.JobOrders.Find(id);
if (jobOrder == null)
{
return HttpNotFound();
}
ViewBag.JobOrderID = jobOrder.ID;
ItemInstance ii = db.ItemInstances.Where(x => x.serialNumber == jobOrder.serialNumber).FirstOrDefault();
Item item = db.Items.Find(ii.ItemID);
var vm = new ItemViewModel
{
Id = item.ID,
ItemId = item.ItemID,
ItemName = item.Name,
Parts = new List<ItemPartViewModel>(),
Components = new List<ItemComponentViewModel>(),
ComponentParts = new List<ComponentPartViewModel>(),
ComponentSubComps = new List<ComponentSubCompViewModel>(),
SubCompParts = new List<SubCompPartViewModel>(),
SubCompSubComps = new List<SubCompSubCompViewModel>(),
SubCompSubCompParts = new List<SubCompSubCompPartViewModel>()
};
foreach (ItemHasParts ihp in item.IHP)
{
Part part = db.Parts.Find(ihp.PartID);
vm.Parts.Add(new ItemPartViewModel
{
ID = part.ID,
PartID = part.PartID,
PartLink = part.PartIDLink,
MFGNumber = part.MFG_number,
QtyInItem = ihp.qty,
OnHand = part.On_Hand,
OnWorkOrder = part.On_Order_Count(true, true),
Committed = part.CommittedCount(true, true),
FSTK = part.FSTK,
PartName = part.Name,
SelectedActionType = PartActionType.Transfer
});
}
return View(vm);
}
The data then is correctly shown on the selection page. But on this page users must select whether they want to harvest/transfer/or dispose of a part. So once the user has finished selecting their options they hit a 'submit' button. This then POSTS to this method
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SpecialOrderSelection(ItemViewModel model)
{
//list of transfers
//list of harvests
//list of disposals
if (ModelState.IsValid)
{
JobOrder jobOrder = db.JobOrders.Find(model.Id);
if (jobOrder == null)
{
return HttpNotFound();
}
ViewBag.JobOrderID = jobOrder.ID;
// do whatever with 'model' and return or redirect to a View
}
//ViewBag.submitted = true;
return RedirectToAction("SpecialOrderSummary", new { ID = jobOrder.ID });
}
The problem here is that for each list, (Parts/Components/ComponentParts/etc.) The ID is null. Why is it null on the POST but not the GET? And how can I fix this so it is not null
Here is the beginning of my View
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
#Html.HiddenFor(model => model.Id)
<div class="form-horizontal">
<h2 class="noprint">Special Order Selection</h2>
<p style="color:red" class="noprint">Please select what is to be done with each component/part</p>
<td align="left">
<hr class="noprint" />
<h4 class="noprint"><b>Work Order ID:</b> #Html.DisplayFor(model => j.ID)</h4>
<br class="noprint" />
And here is the payload of it
<form action="/JODetails/SpecialOrderSelection/3092" method="post"><input name="__RequestVerificationToken" type="hidden" value="LETTERSANDNUMBERS" /><input data-val="true" data-val-number="The field Id must be a number." data-val-required="The Id field is required." id="Id" name="Id" type="hidden" value="3092" /> <div class="form-horizontal">
<h2 class="noprint">Special Order Selection</h2>
<p style="color:red" class="noprint">Please select what is to be done with each component/part</p>
Here is an example of what a 'Part' in my 'parts' list is returning

Your hidden field in the form is Id, which is the Model.Id (ItemViewModel) and not the part! and yet the property you're inspecting on POST is ID (which is the Part ID). You're looking for the item part ID, but you only have the ItemViewModel Id in the form. Since you have other values for item part properties, you must be iterating over that list of parts somewhere in your form. Add a hidden input for the part ID there.
#{
foreach(var part in Model.Parts) {
#Html.HiddenFor(model => part.ID)
}
}

System.Web.Mvc.WebViewPage<T>.Model.get returned null

I am trying to create my first ASP.NET MVC application but since two days I cannot solve my problem.
I am using Entity Framework Code First approach. I want to create DropDownListFor but there is always this error:
System.NullReferenceException
System.Web.Mvc.WebViewPage.Model.get returned null.
My Model:
public class Animals
{
public int AnimalsId { get; set; }
public int ClientsId { get; set; }
public string Name { get; set; }
public int TypesId { get; set; }
public float Age { get; set; }
public float Weight { get; set; }
public virtual Types Types { get; set; }
public IEnumerable<Clients> ClientsList { get; set; }
public virtual ICollection<BookVisit> AnimalsVisits { get; set; }
}
My controller:
public ActionResult Create([Bind(Include = "AnimalsId, ClientsId, Name, TypesId, Age, Weight")] Animals animals)
{
var person = new List<Clients>
{
new Clients { ClientsId = 50, Name = "Timo", Surname = "Werner", Email = "timo.werner#gmail.com", Phone = 123123123 }
};
var animalsView = new Animals
{
ClientsList = person.Select(x => new Clients
{
ClientsId = x.ClientsId
})
};
if (ModelState.IsValid)
{
db.Animals.Add(animals);
db.SaveChanges();
return RedirectToAction("List", "Animal");
}
return View(animalsView);
}
My view (only #model and dropdown):
#model xyz.Models.Animals
#Html.DropDownListFor(model => model.ClientsId, new SelectList(Model.ClientsList, "ClientsId", "Name", "Surname", "Email", "Phone"))
Could you please take a look ?

From the comments, it looks like you are not passing a valid view model object to the view. Your view code is expecting a valid model passed to it and the helper methods are using different properties of that.
public ActionResult Create()
{
var clients = new List<Clients>
{
new Clients { ClientsId = 50, Name = "Timo" },
new Clients { ClientsId = 51, Name = "Microsoft" }
};
var vm = new Animals
{
ClientsList = clients
};
return View(vm);
}
Also your current code which calls the DropDownListFor is wrong. When you create a SelectList from a collection, you have to pass the dataValue field and dataText fields.
#model Animals
#Html.DropDownListFor(model => model.ClientsId,
new SelectList(Model.ClientsList, "ClientsId", "Name"))

This error may also be caused by trying to use a null model in razor view. In such case check if the model is null or not before using it as shown below:
#if (Model != null) {
<a onclick="get('#Url.Action("GetEmployee", "DemoController")', #Model.Id)" ></a>
}

ASP.NET MVC DropDownList not setting selected value

Consider the following model:
public class TagType
{
public int Id { get; set; }
public string Description { get; set; }
}
public class Tag
{
public int Id { get; set; }
public string Description { get; set; }
public TagType TagType { get; set; }
public DropDownListViewModel TagTypeViewModel { get; set; }
public int TagTypeId { get; set; }
}
I have the following Action in a controller:
public ActionResult Edit(int id)
{
// Load from database
IEnumerable<TagType> tagTypes = TagTypeDal.GetAll().ToList();
Tag tag = TagDal.Get(id);
tag.TagTypeViewModel = new DropDownListViewModel();
tag.TagTypeViewModel.Items = new List<SelectListItem>();
tag.TagTypeViewModel.Items.Add(new SelectListItem { Text = "None", Value = "-1" });
tag.TagTypeViewModel.Items.AddRange(tagTypes
.Select(tt => new SelectListItem
{
Text = tt.Description,
Value = tt.Id.ToString(),
Selected = tt.Id == tag.TagType.Id
}).ToList());
return View(tag);
}
The select list has one element that has Selected=true, and it's not the first element.
And on my Edit.cshtml I have:
#model Models.Tag
#Html.DropDownListFor(model => model.TagTypeId,
#Model.TagTypeViewModel.Items,
new { #class = "form-control" })
My problem is that the generated drop down never selects the element that has Selected=true, it always shows the first element.
Am I calling the wrong overload for DropDownListFor? Or am I building the select list wrong? Or is it somethig else?

You should fill model.TagTypeId with selected TagTypeId in your Controller.
DropDownListFor selected value depends on first parameter value.

Fill one property of class by selecting one value on dropdownlist of another model

I have a class Client that have some properties in particular one is restriction_type. Also, I create another class Restriction with an ID and a name properties. The name property correspond to the restriction_type.
Then I display the name of all restrictions in my database in the dropdown list:
#Html.ActionLink("Create New", "Create")
#using (Html.BeginForm("AddRestrictions","Restrictions",FormMethod.Get)){
<p> Type de restriction:
#Html.DropDownList("ClientRestr_type", "All")
</p>
<input type="submit"value="Ajouter"/>
}
That is my controller:
public ActionResult AddRestriction(string ClientRestr_type, Restriction restriction)
{
var RestrLst = new List<string>();
var RestrQry = from d in db.Restrictions
orderby d.name
select d.name;
RestrLst.AddRange(RestrQry.Distinct());
ViewBag.ClientRestr_type = new SelectList(RestrLst);
var clients = from c in db.Restrictions select c;
if (string.IsNullOrEmpty(ClientRestr_type))
return View();
else
{
if (ModelState.IsValid)
{
// Here I have maybe to find the way to solve my problem
}
}
So I want to add the name property of Restriction in the restriction_type property of my Model Client.
Model Client:
public class Client
{
[Required]
public int ID
{
get;
set;
}
[Required]
public string compte
{
get;
set;
}
[Required]
public string portefeuille
{
get;
set;
}
[Required]
public String restriction_type
{
get;
set;
}
[Required]
public Boolean etat
{
get;
set;
}
public Boolean decision
{
get;
set;
}
Model Restriction:
public class Restriction
{
public int restrictionID
{
get;
set;
}
public string name
{
get;
set;
}
}
What do you think about my GetRestrictions() method
private SelectList GetRestrictions()
{
var RestrLst = new List<string>();
var RestrQry = from d in db.Restrictions
orderby d.name
select d.name;
RestrLst.AddRange(RestrQry.Distinct());
return new SelectList(RestrLst);
}
But unfortunately I have an error: Impossible to convert System.Web.Mvc.SelectList to MyApp.Models.Client at line:
model.RestrictionList = GetRestrictions();
I don't understand why
Thank you for your help!

A simplified example:
View model
public class ClientVM
{
public Client Client { get; set; }
public SelectList RestrictionList { get; set; }
}
Controller
[HttpGet]
public ActionResult Create()
{
ClientVM model = new ClientVM();
model.Client = new Client();
model.RestrictionList = GetRestrictions(); // your code to return the select list
return View("Edit", model);
}
[HttpGet]
public ActionResult Edit(int ID)
{
ClientVM model = new ClientVM();
model.Client = // call database to get client based on ID
model.RestrictionList = GetRestrictions();
return View(model);
}
[HttpPost]
public ActionResult Edit(ClientVM model)
{
if (!ModelState.IsValid)
{
model.RestrictionList = GetRestrictions();
return View(model);
}
Client client = model.Client;
// Save and redirect
....
}
View
#model YourNamespace.ClientVM
#using (Html.BeginForm() {
#Html.TextBoxFor(m => m.Client.ID)
#Html.TextBoxFor(m => m.Client.compte)
...
#Html.DropDownListFor(m => m.Client.restriction_type, Model.RestrictionList)
<input type="submit" value="Save" />
}