How to get data of selected rows of table in controller using ajax in asp.net core?

You could use JQuery Selectors and the find method to find the elements in the selected row, and get the value. After that, you could create a JavaScript object to store these values, then, send them to the controller and do something.

Please refer the following sample code:

Controller:

    public IActionResult QuestionIndex()
    {
        //test data
        List<AddQuestionViewModel> items = new List<AddQuestionViewModel>()
        {
            new AddQuestionViewModel(){
                QuestionId=101, 
                questionTitle="What's you name?", 
                UserId="User A", 
                ExamId=1, 
                Grade= 2, 
                IsShow=true, 
                IsSelect=true,
                choice = new List<ChoiceQuestionSelection>(){
                    new ChoiceQuestionSelection(){ QuestionId=101, Choice="C1", IsTrue=true, ChoiceQuestionSelectionId=1}
                }
            },
            new AddQuestionViewModel(){
                QuestionId=102,
                questionTitle="How are you?",
                UserId="User B",
                ExamId=2,
                Grade= 2,
                IsShow=true,
                IsSelect=true,
                choice = new List<ChoiceQuestionSelection>(){
                    new ChoiceQuestionSelection(){ QuestionId=102, Choice="C2", IsTrue=true, ChoiceQuestionSelectionId=1}
                }
            } 
        };

        return View(items);
    }

    //Since we might submit multiple selected items, it is better to use a List to receive the records.
    [HttpPost]
    public IActionResult CreateQuestionFromQuestionBank(List<AddQuestionViewModel> addQuestions)
    {
        //to do something

        return Json(new { status = "Success", redirectToUrl = "/Reports/Index" });
    }

Index View page:

@model IEnumerable<WebApplication.Models.AddQuestionViewModel>

@{
    ViewData["Title"] = "QuestionIndex";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<form id="QuestionsForm" method="post" asp-action="CreateQuestionFromQuestionBank">
    <table class="table" id="tblQuestions">
        <thead>
            <tr>
                <th></th>
                <th></th>
                <th>سوال</th>
                <th>نمره</th>
                <th>نوع</th>
                <th>دستورات</th>
            </tr>
        </thead>
        <tbody>
            @foreach (var item in Model)
            {
                <tr>
                    <td><input type="checkbox" /></td>
                    <td>
                        <input type="hidden" name="qId" asp-for="@item.QuestionId" />@item.QuestionId
                    </td>
                    <td>
                        <input name="questionTitle" asp-for="@item.questionTitle" disabled
                               value="@item.questionTitle" />
                    </td>
                    <td>
                        <input name="Grade" id="Grade" asp-for="@item.Grade"
                               readonly="readonly" value="@item.Grade" />

                    </td>

                    @if (item.choice.Any(ch => ch.QuestionId == item.QuestionId))
                    {
                        <td>
                            گزینه ای
                            <div>
                                <br />
                                @foreach (var choice in item.choice.Where(q => q.QuestionId
== item.QuestionId))
                                {
                                    <div class="form-group" name="choices">
                                        <label class="radio-inline" style="">
                                            <input type="radio" disabled value=""
                                                   @((choice.IsTrue) ? "checked" : "")>
                                            <input type="text" value="@choice.Choice" asp-
                                                   for="@item.choice" readonly="readonly" />

                                        </label>
                                    </div> 
                                }
                            </div>
                        </td>
                    }
                    else if (item.trueFalse.Any(q => q.QuestionId == item.QuestionId))
                    {
                        <td>
                            صحیح و غلط
                            <div>
                                <br />
                                @foreach (var trueFalse in item.trueFalse.Where(q =>
q.QuestionId == item.QuestionId))
                                {
                                    <div>
                                        @if (trueFalse.IsTrue)
                                        {
                                            <div>صحیح</div>
                                        }
                                        else
                                        {
                                            <div>غلط</div>
                                        }
                                    </div>
                                }
                            </div>
                        </td>
                    }
                    else
                    {
                        <td>تشریحی</td>
                    }
                    <td></td>
                </tr> 
            }

        </tbody>
    </table>
    <input name="submit" type="submit" value="save" />
</form>

The Scripts in the Index page:

@section Scripts{ 
<script>
    $(function () {
        $(':submit').click(function (event) { 
            event.preventDefault(); 
            //define an array to store the selected AddQuestionViewModel list.
            var selectedModel = [];
            //loop through all checked checkbox.
            $("input[type='checkbox']:checked").each(function (index, item) {
                //get current row
                var tr = $(item).closest('tr');
                //define an object to store the AddQuestionViewModel information.
                var model = new Object();

                //using find method to find element from current row, and then get the value.
                model.questionId = $(tr).find("input[name='qId']").val();
                model.questionTitle = $(tr).find("input[name='questionTitle']").val();
                model.grade = $(tr).find("input[name='Grade']").val();

                //define an array to store the choise list.
                var choicearray = [];
                //define an object to store the choise information.
                var choice = new Object();
                choice.IsTrue = $(tr).find("div[name='choices']").find("input:radio").is(':checked') ? true : false;
                choice.choice = $(tr).find("div[name='choices']").find("input[type='text']").val();
                choicearray.push(choice);
 
                model.choice = choicearray;
                //use the same method to get all the required values.
                selectedModel.push(model);
            });
            var frm = $('#QuestionsForm');
            $.ajax({
                url: frm.attr('action'),
                method: "POST",
                data: { addQuestions: selectedModel }, 
            }).done(function (response) {
                window.location.href = response.redirectToUrl;
            });

        });
    });
</script>
}

The test screenshot like this: