model binding asp.net core web api - asp.net-mvc

Question

Im trying to bind model, but when i bind smartphone or laptop props, im losing myContnet main prop id, here is mainCont:
`namespace Bind.Models
{
public class MainCont
{
public int Id{ get; set; }
public Device Device { get; set; }
}
}`
using Bind.Models;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace Bind
{
public class DeviceModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
{
throw new ArgumentNullException(nameof(bindingContext));
}
var model1 = new MainCont();
var select = bindingContext.ValueProvider.GetValue("select").FirstValue;
if (select == "SmartPhone")
{
var model2 = new SmartPhone();
model2.screensize = bindingContext.ValueProvider.GetValue("screensize").FirstValue;
model2.imei = bindingContext.ValueProvider.GetValue("imei").FirstValue;
model1.Device = model2;
}
else if (select == "Laptop")
{
var model2 = new Laptop();
model2.CPU = bindingContext.ValueProvider.GetValue("CPU").FirstValue;
model2.GPu = bindingContext.ValueProvider.GetValue("GPu").FirstValue;
model1.Device = model2;
}
bindingContext.Result = ModelBindingResult.Success(model1);
return Task.CompletedTask;
}
}
}
i cant set id, of course in DeviceBinder i wrote new mainCont(), and how can i solve it? Sorry for bad english ;)

Answer 1

Firstly,you need to add a input in your view,so that you can pass the Id when form post.
Here is a demo:
Index.cshtml(I use a hidden input,if you want to edit the Id in the view,you can remove hidden):
<form asp-action="create" asp-controller="home" method="post">
<input asp-for="Id" hidden>
<select id="select" name="select">
<option value="SmartPhone">SmartPhone </option>
<option value="Laptop">Laptop </option>
</select>
<div id="sample"></div>
<button type="submit">გაგზავნა</button>
</form>
And then,in your CustomModelBinder,bind it to model:
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
{
throw new ArgumentNullException(nameof(bindingContext));
}
var model1 = new MainCont();
//bind the Id here
model1.Id= Convert.ToInt32(bindingContext.ValueProvider.GetValue("Id").FirstValue);
var select = bindingContext.ValueProvider.GetValue("select").FirstValue;
if (select == "SmartPhone")
{
var model2 = new SmartPhone();
model2.screensize = bindingContext.ValueProvider.GetValue("screensize").FirstValue;
model2.imei = bindingContext.ValueProvider.GetValue("imei").FirstValue;
model1.Device = model2;
}
else if (select == "Laptop")
{
var model2 = new Laptop();
model2.CPU = bindingContext.ValueProvider.GetValue("CPU").FirstValue;
model2.GPu = bindingContext.ValueProvider.GetValue("GPu").FirstValue;
model1.Device = model2;
}
bindingContext.Result = ModelBindingResult.Success(model1);
return Task.CompletedTask;
}
Controller(When create view,I give the Id to the view):
public IActionResult Index()
{
return View(new MainCont { Id=1});
}
result: