How to pass value selected from DropDownList to Controller - MVC - html

Question

I am having trouble getting the value selected in my dropdownlist in my Homecontroller. I have the DropDownList in a form but I think my format may be wrong. I'm new to MVC and new to HTML so I'm struggling pretty hard. Would appreciate some help.
Here is my controller (I put this in my homecontroller, is that a bad idea?):
public IActionResult Index()
{
_ = new List<MyjsonSettings>();
var obj = new StatusPortController(configuration);
List<MyjsonSettings> PortList = obj.GetPortNum();
List<SelectListItem> AppNameList = PopulateDropDown(PortList);
ViewData["Applications"] = AppNameList;
return View("~/Views/Home/dataview.cshtml");
}
public List<SelectListItem> PopulateDropDown(List<MyjsonSettings> PortList)
{
List<SelectListItem> AppNameList = new List<SelectListItem>();
for (int i = 0; i < PortList.Count(); i++)
{
AppNameList.Add(new SelectListItem {
Text = PortList[i].NAME, Value = (i+1).ToString()
});
}
return AppNameList;
}
Here is the view (dataview.cshtml):
#{
ViewData["Title"] = "Home Page";
}
#using (Html.BeginForm("Index", "Home", FormMethod.Post))
{
#Html.DropDownList("Applications", ViewData["AppNameList"] as List<SelectListItem>)
<input type="submit" value="submit" />
}
Any ideas? No errors when I run, I just don't know how to get the response back.

Answer 1

you can rebuild the structure to a more usable way, and in order to submit form with drop down list or any type of fields you need to first return a view with Model and then submit the form to an action that receive same Model type as parameter
example:
model:
public class ApplicationsAddModel {
public ApplicationsAddModel (){
//constructer to initialize the list
ApplicationsList = new List<SelectListItem>();
}
public string test{ get; set; }
public int selectedApplicationId { get; set; }
public List<SelectListItem> ApplicationsList { get; set; }
}
controller
//this is the first action that return the model
[HttpGet]
public IActionResult Index()
{
ApplicationsAddModel model = new ApplicationsAddModel ();
//fill your drop down list
List<SelectListItem> AppNameList = PopulateDropDown(PortList);
model.ApplicationsList = AppNameList;
return View(model);
}
[HttpPost] //recive the form
public IActionResult Index(ApplicationsAddModel SubmittedModel)
{
var selectedApplication = SubmittedModel.selectedApplicationId; //get the selected value from ddl
//fill your drop down list
List<SelectListItem> AppNameList = PopulateDropDown(PortList);
model.ApplicationsList = AppNameList;
return View(SubmittedModel);
}
view (index.cshtml):
#model projectName.ApplicationsAddModel
#{ ViewData["Title"] = "Home Page"; }
#using (Html.BeginForm("Index", "Home", FormMethod.Post))
{
#Html.LabelFor(m => m.selectedApplicationId)
#Html.DropDownListFor(m => m.selectedApplicationId, Model.ApplicationsList, "---", new { #class = "custom-select form-control" })
<input type="submit" value="submit" />
}
summary:
in MVC when you have to submit data to controller, create your model, go to controller and create your first action (GET) which fill the form with initial data and fill your drop down lists if exist, then create the (POST) action which receive the model of same type of the view and MVC will bind it automatically for you
best regards