Attach Required Attribute to To A Property At Runtime

Question

User-309523270 posted

Hello,

I have a class which is used in a PartialView.  This class is used in a ViewModel.  There are 2 views which use the partial view.  In view1, some properties are required entries. In view2, these are not required.

Is there anyway for me to attach a [Required] attribute in the property of the class at runtime before rendering the views?

I'm using MVC, ASP Core 2.0.

Thanks!

tinac99

Answer 1

User-474980206 posted

attributes are compile time attributes, so they can not change at runtime. you count use custom validation attibutues that look at other properties to determine. google if validation. you could have two view models.

Answer 2

User1686398519 posted

Hi tinac99,

tinac99

Is there anyway for me to attach a [Required] attribute in the property of the class at runtime before rendering the views?

As far as I know, this idea is almost impossible to achieve, but I have a solution to achieve your needs. If you are willing to try it, you can refer to this example.

• You can use the required method to make the element necessary.
• You need to reference the "jquery.min.js" file.

Model

public class Test1ViewModel
{
   public string Id { get; set; }
   public string name { get; set; }
}

Controller

        public IActionResult Test1()
        {
            return View();
        }
        public IActionResult Test2()
        {
            return View();
        }
        [HttpPost]
        public IActionResult Test3(Test1ViewModel test1)
        {
            return View();
        }

Test1

<h1>Id is not required</h1>
@Html.ActionLink("To Test2", "Test2", "Test6")
@await Html.PartialAsync("PartialTest")

Test2

<h1>Id is required</h1>
@Html.ActionLink("To Test1", "Test1", "Test6")
@await Html.PartialAsync("PartialTest")
@section scripts{
    <script>
        $(function () {
            $("#Id").attr("required", "true");
        });
    </script>
}

Test3

<h1>Success</h1>
@Html.ActionLink("To Test2", "Test2", "Test6")
@Html.ActionLink("To Test1", "Test1", "Test6")

PartialTest

@model WebApplication7.Models.Test1ViewModel
@using (Html.BeginForm("Test3", "Test6", FormMethod.Post))
{
    <div class="form-group row">
        @Html.LabelFor(m => m.Id, new { @class = "col-sm-2 col-form-label" })
        <div class="col-sm-10">
            @Html.TextBoxFor(m => m.Id, new { @class = "form-control" })
        </div>
    </div>
    <div class="form-group row">
        @Html.LabelFor(m => m.name, new { @class = "col-sm-2 col-form-label" })
        <div class="col-sm-10">
            @Html.TextBoxFor(m => m.name, new { @class = "form-control" })
        </div>
    </div>
    <button type="submit">submit</button>
}

Here is the result.

Best Regards,

YihuiSun