Model property gets a value even if not assigned-CodePudding

I have a controller action that returns a partial view with an empty model. But when I inspect the browser it shows the hidden element for Id has a value. why is this happening?

Here's my code:

Controller:

[HttpGet]
public async Task<IActionResult> GetItemForm(int? id)
{
    try
    {
        //var account = await _uow.CashAccounts.GetAsync((int)id);

        //if (account == null)
        //    return Json(new NotFound());

        var model = new AccountHistoryFormModel();
        //model.AccountId = (int)id;

        return PartialView("_AddFundForm", model);
    }
    catch (Exception ex)
    {
        return Json(new InternalError(ex.Message));
    }
}

View:

@using Trucking.WebUI.Models.BankAccount
@model AccountHistoryFormModel

@using (Html.BeginForm("save", "accounthistory", FormMethod.Post, new { id = "add-fund-form", @class = "row g-2" }))
{
    @Html.HiddenFor(x => x.Id)
    //@Html.HiddenFor(x => x.AccountId)
    <div >
        @Html.LabelFor(x => x.Amount, new { @class = "form-label form-label-sm" })
        @Html.TextBoxFor(x => x.Amount, new { @class = "form-control form-control-sm" })
        @Html.ValidationMessageFor(x => x.Amount, "", new { @ })
    </div>
    <div >
        @Html.LabelFor(x => x.DateDeposit, new { @class = "form-label form-label-sm" })
        @Html.TextBoxFor(x => x.DateDeposit, "{0:yyyy-MM-dd}", new { @type = "date", @class = "form-control form-control-sm" })
        @Html.ValidationMessageFor(x => x.DateDeposit, "", new { @class = "invalid-feedback" })
    </div>
}

AccountHistoryFormModel:

public class AccountHistoryFormModel : BaseModel
{
    public AccountHistoryFormModel()
    {
        Action = "DEPOSIT";
        DateDeposit = DateTime.Now;
    }

    public int AccountId { get; set; }

    [Range(1.0, double.MaxValue, ErrorMessage = "Amount must not be 0.")]
    public decimal Amount { get; set; }
    public string Action { get; }

    [Display(Name = "Date Deposit")]
    public DateTime DateDeposit { get; set; }
}

Browser:

Thank you in advance.

CodePudding user response：

This is exactly what the strongly typed HTML Helper for a hidden field Html.HiddenFor() do. It takes as a parameter System.Linq.Expressions.Expression<Func<TModel,TProperty>> expression and generate a MvcHtmlString.

In your case because the view model has Id property with value 2 the following HTML string was generated:

<input id="Id" name="Id" type="hidden" value="2" />

CodePudding user response：

Check AccountHistoryFormModel's constructor ! probably you set id property on this class.