Question

我正试图在我的视图中第一次写入模型：第一次写入模型时，我得到ArgumentOutOfRangeException。

首次写入数组时出错：

private IAdditionalQuestionsService _service;
private SelectedAdditionalQuestionAnswerModel _model;
private void InitializeController()
{
    _service = GetObject<IAdditionalQuestionsService>();
    //GetPageHeaderText(inst);
    ViewBag.GetPageTitle = "Additional Questions";
}

[HttpGet]
public virtual ActionResult Edit()
{
    Institution inst = _service.GetInstitution(State.GetInstitutionRecordId());
    _model = GetObject<SelectedAdditionalQuestionAnswerModel>();
    _model.AddQuestAnswModel = new List<AdditionalQuestionAnswerModel>();
    GetPageConfiguration1(inst);
    return View(_model);
}

AdditionalQuestionAnswerModel m = GetObject<AdditionalQuestionAnswerModel>();
int c = 0;
foreach (var x in inst.AdditionalQuestions)
{
    foreach (var y in x.AdditionalQuestionAnswers)
    {
        // Error is happening on next line *************
        _model.AddQuestAnswModel[c].QuestionText = x.QuestionText;
        _model.AddQuestAnswModel[c].InstitutionId = x.InstitutionId;
        _model.AddQuestAnswModel[c].AdditionalQuestionId = x.Id;
        _model.AddQuestAnswModel[c].AnswerText = y.AnswerText;
        _model.AddQuestAnswModel[c].IsSelected = false;
        c++;
    }
}

Answer 1

您无法使用_model.AddQuestAnswModel[c]，因为您从未在列表中添加任何项目。

而不是那样，创建一个新对象并设置其值，然后将该项添加到列表中。

这样的事情：

AdditionalQuestionAnswerModel newItem = new AdditionalQuestionAnswerModel();

//set the values here to newItem

_model.AddQuestAnswModel.Add(newItem);

Answer 2

您首先要实例化您的列表

_model.AddQuestAnswModel = new List<AdditionalQuestionAnswerModel>();

然后你尝试访问第一个元素

_model.AddQuestAnswModel[c] // c == 0

不向列表中添加任何元素。

在尝试按索引访问列表之前添加元素，或者更简单：

foreach (var y in x.AdditionalQuestionAnswers)
{
    AdditionalQuestionAnswerModel newObj = new AdditionalQuestionAnswerModel
    {
         QuestionText = x.QuestionText;
         InstitutionId = x.InstitutionId;
         AdditionalQuestionId = x.Id;
         AnswerText = y.AnswerText;
         IsSelected = false;
    };

    _model.AddQuestAnswModel.Add(newObj);
}

Answer 3

Ir表示您_model.AddQuestAnswModel处的指定邮件中没有任何项目，并且从您的代码中，我发现_model.AddQuestAnswModel只能使用new List<AdditionalQuestionAnswerModel>()启动，因此它不包含项目（除非你在构造函数中这样做）。

你需要像这样填写：

_model.AddQuestAnswModel.Add(item);

写入模型时ArgumentOutOfRangeException

3 个答案: