.NET Core 视图属性名称与模型属性名称不同

Question

I have an ajax function that returns an error message to a field when an error occurs serverside.

This is how I show my errors:

$.each(result.errors, function (index, item) {
    // Get message placeholder
    var element = $('[data-valmsg-for="' + item.propertyName + '"]');
    element.empty();
    // Update message
    element.append($('<span></span>').text(item.errorMessage));
    // Update class names
    element.removeClass('field-validation-valid').addClass('field-validation-error');
    $('#' + item.propertyName).removeClass('valid').addClass('input-validation-error');
});

This is supposed to read the returned propertyname which is the name of my field and display the message on it.

This is the field. It is a dropdownlist

<div class="row">
    <div class="col-sm-12">
        <div class="form-group">
            @Html.HiddenFor(m => m.UserId)
            @Html.DropDownListFor(m => m.BranchDropdownListViewModel.BranchId, Model.BranchDropdownListViewModel.Branch, "Select Branch", new { @class = "form-control" })
            @Html.ValidationMessageFor(m => m.BranchDropdownListViewModel.BranchId)
        </div>
    </div>
</div>

When I inspect the code, the name of this dropdown is BranchDropdownListViewModel.BranchId

However, in my controller when I try to find the name of this field like this:

ModelState.AddModelError(nameof(Input.BranchDropdownListViewModel.BranchId), "Branch already exists");

It shows BranchId as the name of the field only.

This is the model:

public class UserBranchDetailsViewModel
{
    public string Id { get; set; }
    public string UserId { get; set; }
    public string TenantId { get; set; }
    public BranchDropdownListViewModel BranchDropdownListViewModel { get; set; }
}

public class BranchDropdownListViewModel
{
    [Required]
    [Display(Name = "Branch")]
    public string BranchId { get; set; }
    public IEnumerable<SelectListItem> Branch { get; set; }
}

How can I match the name shown in the view from the controller? Must I do it manually?

Answer 1

The use of the nameof would only produce the last part of the property name, which in your case is BranchId .

Since getting an injected HtmlHelper is not so straightforward, I would suggest you to do

ModelState.AddModelError($"{nameof(Input.BranchDropdownListViewModel)}.{nameof(Input.BranchDropdownListViewModel.BranchId)}", "Branch already exists");

But if you really want to use the HtmlHelper , look at this method HtmlHelper.NameFor() .