Databinding Problems

Question

Hello everyone and thanks for the help in advance. I am developing a MVC application that posts a list of a model to a controller. The model:

    public class tbl_Log_Exams     {         public int? ID { get; set; }          public int? ClientID { get; set; }          public int? VisitID { get; set; }          public string? MRNumber { get; set; }          public DateTime? TimeEntered { get; set; }          public string? EnteredBy { get; set; }          public string? Normal { get; set; }          public string? Exceptions { get; set; }          public string? Category { get; set; }          public int? CategoryCode { get; set; }      }

The posted data:

tbl_Log_Exams[0].CategoryCode : 1

tbl_Log_Exams[0].MRNumber : 12345

tbl_Log_Exams[0].VisitID : 98765

tbl_Log_Exams[0].Normal : All

tbl_Log_Exams[0].Exceptions : None

and the receiving controller:

public ActionResult ExamResults(List<tbl_Log_Exams> model

However, on the receiving controller, Model.Count returns zero. I am not sure what the problem is. Any help would be appreciated.

Answer 1

Hi @Kmcnet,

You did not provide the front-end code, so it is not clear how you post data,

you can refer to the following example.

@model List<MvcDemo612.Models.tbl_Log_Exams>

@{
    ViewBag.Title = "ExamResults";
}

<h2>ExamResults</h2>


<form method="post" action="/Home/ExamResults">
    <table class="table">
        <thead>
            <tr>
                <th>
                    @Html.LabelFor(model => Model[0].ClientID)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].VisitID)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].MRNumber)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].TimeEntered)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].CategoryCode)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].Category)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].EnteredBy)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].Normal)
                </th>
                <th>
                    @Html.LabelFor(model => Model[0].Exceptions)
                </th>
                <th></th>
            </tr>
        </thead>
        <tbody>
            @for (var i = 0; i < Model.Count; i++)
            {
                <tr>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].ClientID)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].VisitID)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].MRNumber)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].TimeEntered)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].CategoryCode)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].Category)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].EnteredBy)
                    </td>
                    <td>
                        @Html.TextBoxFor(modelItem => Model[0].Normal)
                    </td>
                    <td>
                        @Html.DisplayFor(modelItem => Model[0].Exceptions)
                    </td>
                </tr>
            }
        </tbody>
    </table>
    <div>
        <input type="submit" value="submit" />
    </div>
</form>

 public ActionResult ExamResults()
        {
            List<tbl_Log_Exams> list = List();
            return View(list);
          
        }
        [HttpPost]
        public ActionResult ExamResults(List<tbl_Log_Exams> model)
        {
           
            return Json(model);
        }
        private List<tbl_Log_Exams> List()
        {
            return new List<tbl_Log_Exams>() {
                new tbl_Log_Exams()
                {
                    ClientID = 1,
                    VisitID= 1,
                    MRNumber= "123",
                    TimeEntered=DateTime.Now,
                    CategoryCode= 1,
                    Category= "1",
                    EnteredBy= "1",
                    Normal= "All",
                    Exceptions= "None",
                },
                new tbl_Log_Exams()
                {
                    ClientID = 2,
                    VisitID= 2,
                    MRNumber= "123",
                    TimeEntered=DateTime.Now,
                    CategoryCode= 1,
                    Category= "2",
                    EnteredBy= "2",
                    Normal= "All",
                    Exceptions= "",
                }
            };
        }

Best regards,
Lan Huang

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Answer 2

The action is designed to look for an collection of tbl_Log_Exams.

[0].ID

Your view design is based on a class with a List<tbl_Log_Exams> tbl_Log_Exams property.

tbl_Log_Exams[0].ID

The action parameter should be the class type and name that has the tbl_Log_Exams property not "List<tbl_Log_Exams> model".

Your model is like the following.

    public class MyViewModel
    {
        public List<tbl_Log_Exam> tbl_Log_Exams { get; set; }
    }
    public class tbl_Log_Exam
    {
        public int? ID { get; set; }
    }

Therefore the action parameter should be...

        [HttpPost]
        public ActionResult Index(MyViewModel model)
        {
            return Json(model);
        }