System.NullReferenceException: 'Object reference not set to an instance of an object.'

Question

System.NullReferenceException: 'Object reference not set to an instance of an object.'

Case Ventil 0

SystemNullReferenceException

I would like to insert product 2 or anymore but Model.Selects.get returned null! I do not understand how I resolve this problem. Can you help me please! Thanks for your support

Anonymous

2024-12-19T14:09:08.6833333+00:00

Hi @Case Ventil , according to your screenshot, we could see that model.Selects is null, so that I'm afraid you need to check whether you passed value into CreateOrderModel. Could you please share more codes related to your issue, such as how you submit the data in view and how you received the data in your controller?
Case Ventil 0 Reputation points

2024-12-19T14:16:44.9566667+00:00

Anonymous

Hi, according to your screenshot, we could see that you are having public List<SelectListItem> Products which is used for select dropdown. I had a complete sample before and maybe you can refer to my sample codes. Please feel free to let me know if it doesn't work. By the way, it's better to share your codes instead of screenshots, therefore we could test with your codes.

@model WebAppMvc.Controllers.GradeGlass
<div class="form-group">
	<label asp-for="CurrentGradeId" class="col-form-label">Grade Name</label>
	<select asp-for="CurrentGradeId" asp-items="@Model.SelectListGrades" class="form-control" id="GradeDropdown">
		<option value="0" selected disable">Choose...</option>
	</select>
	<span asp-validation-for="CurrentGradeId" class="text-danger"></span>
</div>
 
 
 public class GradeGlass {
     public string CurrentGradeId { get; set; }
     public string CurrentClassroomId { get; set; }
     public string Id { get; set; }
     public string name { get; set; }
     public List<SelectListItem> SelectListGrades { get; set; }
 }
public IActionResult Index()
{
	var model = new GradeGlass { 
	 SelectListGrades = new List<SelectListItem> {
		 new SelectListItem{
			 Text = "Grade 1", Value = "g1",Selected = false
		 },
		 new SelectListItem{
			 Text = "Grade 2", Value = "g2",Selected = false
		 },
		 new SelectListItem{
			 Text = "Grade 3",Value = "g3",Selected = false
		 }
	 },
	};
	return View(model);
}
[HttpPost]
public IActionResult Create(GradeGlass model) {
    if (ModelState.IsValid)
    {
        return RedirectToAction(nameof(Index));
    }
    return View(model);
}

Case Ventil 0 Reputation points

2024-12-20T06:01:28.3966667+00:00

I was not solve this problem I'm gonna make crazy
Anonymous

2024-12-20T06:06:34.1366667+00:00

May I know what does this line mean? - > "I would like to insert product 2 or anymore but Model.Selects.get returned null!" According to your screenshot, it looks like you are trying to submit the current selected Product. But I'm not sure what you are trying to do in your Controller. Could you pls share your codes instead of the screenshot? And your ultimate goal?
Anonymous

2024-12-20T06:33:16.4233333+00:00

Hi, you could take a look at my sample. In my view, I have <select asp-for="CurrentGradeId" so that when I submit my form, CurrentGradeId property will have value which should be the value of the selected option, but SelectListGrades shouldn't have value in the post request as this is a list for selection item, which can't be bind to the model. Normally speaking, submitting will only submit the selected value, but not the selection list.

Your answer

Anonymous

2024-12-19T14:09:08.6833333+00:00

Hi @Case Ventil , according to your screenshot, we could see that model.Selects is null, so that I'm afraid you need to check whether you passed value into CreateOrderModel. Could you please share more codes related to your issue, such as how you submit the data in view and how you received the data in your controller?
Case Ventil 0 Reputation points

2024-12-19T14:16:44.9566667+00:00
Anonymous

2024-12-19T14:47:48.78+00:00

Hi, according to your screenshot, we could see that you are having public List<SelectListItem> Products which is used for select dropdown. I had a complete sample before and maybe you can refer to my sample codes. Please feel free to let me know if it doesn't work. By the way, it's better to share your codes instead of screenshots, therefore we could test with your codes.

@model WebAppMvc.Controllers.GradeGlass <div class="form-group"> <label asp-for="CurrentGradeId" class="col-form-label">Grade Name</label> <select asp-for="CurrentGradeId" asp-items="@Model.SelectListGrades" class="form-control" id="GradeDropdown"> <option value="0" selected disable">Choose...</option> </select> <span asp-validation-for="CurrentGradeId" class="text-danger"></span> </div> public class GradeGlass { public string CurrentGradeId { get; set; } public string CurrentClassroomId { get; set; } public string Id { get; set; } public string name { get; set; } public List<SelectListItem> SelectListGrades { get; set; } } public IActionResult Index() { var model = new GradeGlass { SelectListGrades = new List<SelectListItem> { new SelectListItem{ Text = "Grade 1", Value = "g1",Selected = false }, new SelectListItem{ Text = "Grade 2", Value = "g2",Selected = false }, new SelectListItem{ Text = "Grade 3",Value = "g3",Selected = false } }, }; return View(model); } [HttpPost] public IActionResult Create(GradeGlass model) { if (ModelState.IsValid) { return RedirectToAction(nameof(Index)); } return View(model); }
Case Ventil 0 Reputation points

2024-12-20T06:01:28.3966667+00:00

I was not solve this problem I'm gonna make crazy
Anonymous

2024-12-20T06:06:34.1366667+00:00

May I know what does this line mean? - > "I would like to insert product 2 or anymore but Model.Selects.get returned null!" According to your screenshot, it looks like you are trying to submit the current selected Product. But I'm not sure what you are trying to do in your Controller. Could you pls share your codes instead of the screenshot? And your ultimate goal?
Anonymous

2024-12-20T06:33:16.4233333+00:00

Hi, you could take a look at my sample. In my view, I have <select asp-for="CurrentGradeId" so that when I submit my form, CurrentGradeId property will have value which should be the value of the selected option, but SelectListGrades shouldn't have value in the post request as this is a list for selection item, which can't be bind to the model. Normally speaking, submitting will only submit the selected value, but not the selection list.

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System.NullReferenceException: 'Object reference not set to an instance of an object.'

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