How to get an array of elements of one model from the form asp.net core?

Question

I need to get an array of elements of one model from the form. Then return the same array back to shape. Model:

public class Check
{
    public int Id { get; set; }

    public string Text { get; set; }

    public int Number1 {get; set;}
    public int Number2 {get; set;}
}

Controller:

[HttpGet]
    public IActionResult Check(string tema)
    {
        IEnumerable<Check> less = _context.Checks.Where(e => e.Text == tema);

        return View(less);
    }

    [HttpPost]
    public IActionResult Check(IEnumerable<Check> Checks)
    {   
        return View(Checks);
    }

Form:

@model IEnumerable<Check>

@foreach (var check in Model)
{
 <form asp-action="Check" asp-controller="Home" method="post">
  <p>@check?.Text</p>
   <p><input type="text"asp-for="@check.Number1"/></p>

  @if(Number1 == Number2)
   {<p>ok</p>}
 
    <div class="form-group">
        <input type="submit" value="Ok" class="btn btn-default" />
    </div>
  </form>
  }

I have everything working for one model, and if I pass an array, I get an empty form. How to fix it?

Answer 1

1.If you just want to post single model , but the backend you want receive the IEnumerable<Check> , you need add name attribute( name="[0].propertyName" ) to override the asp-for generated name="check.propertyName"

2.For your code, it will generate multiple forms with submit button. If you want to post an array model, you need move <form> and submit button outside foreach loop.

3.If post array model from view to controller. The IEnumerable<Check> Checks is a list model, so the model binding system would find the name by [i].propertyName .

4. <p> element text cannot passed to backend by form submit. If you want to post it, try to add a hidden input.

If post array model from view to controller, change your view like below:

@model IEnumerable<Check>
@{
    int i=0;  //add this...
}
<form asp-action="Check" asp-controller="Home" method="post">
    @foreach (var check in Model)
    {
      <p>
          @check?.Text                                  
          <input type="text"asp-for="@check.Text" name="[@i].Text" hidden/>  @* //add the hidden input*@
      </p>  
                                                     //add the name...
       <p><input type="text"asp-for="@check.Number1" name="[@i].Number1"/></p>

      @if(check.Number1 == check.Number2)
       {<p>ok</p>}
      
        i++;  //add this...
    }
    <div class="form-group">
         <input type="submit" value="Ok" class="btn btn-default" />
    </div>
</form>

---

If you post single model , change your view like below:

@foreach (var check in Model)
{
    <form asp-action="Check " asp-controller="Home" method="post">

    <p>
      @check?.Text                                  
      <input type="text"asp-for="@check.Text" name="[0].Text" hidden/>  @* //add the hidden input*@
    </p>  
                                                  @*add the name...*@
    <p><input type="text"asp-for="@check.Number1" name="[0].Number1"/></p>

     @if(check.Number1 == check.Number2)
     {<p>ok</p>}
    <div class="form-group">
        <input type="submit" value="Ok" class="btn btn-default" />
    </div>
</form>
}