ASP.NET 核心 3.0 Razor 页面 Select 帮助程序未发布值

Question

I am trying to post back a selected value from a dropdown on an ASP.NET Core 3.0 Razor Pages Page. I am getting back the default value every time. I can't see what I am missing.

Here is the code:

Page:

<select asp-for="SelectedReportId" class="form-control" name="ReportSelect"
   asp-items="@(new SelectList(Model.Reports, nameof(ReportsModel.Id), nameof(ReportsModel.ReportName)))">
</select>

Code-behind:

[BindProperty]
public int SelectedReportId { get; set; }

That renders as this on the form:

<select class="form-control" name="ReportSelect" data-val="true" data-val-required="The SelectedReportId field is required." id="SelectedReportId">
   <option value="1">All People</option>
   <option value="2">People Starting With T</option>
</select>

When I post the values, the rest of the form comes through but nothing comes through for SelectedReportId . I tried changing the type to string, in case that was an issue but then it just passes in null instead of 0. I also verified that the list was properly being loaded (of course, you can see that it loads by the HTML being properly rendered).

I tried about every configuration that I could think of without any success. I even cloned the project down to another machine, just to test it out there, but I got the same results.

I am running Visual Studio 2019 16.4.0 Preview 1.0 and the project is a .NET Core 3.0 project.

Answer 1

You are using ReportSelect name for your drop-down while you are trying to bind it to SelectedReportId without specifying explicit binding. Just replace your drop-down name from ReportSelect to SelectedReportId and it will resolve your problem.

<select asp-for="SelectedReportId" class="form-control" name="SelectedReportId"
        asp-items="@(new SelectList(Model.Reports, nameof(ReportsModel.Id),nameof(ReportsModel.ReportName)))">
</select>

Or if you don't want to change your drop-down name then you need to specify property name in your BindProperty attribute.

[BindProperty(Name="ReportSelect")]
public int SelectedReportId { get; set; }

Hopefully, It will resolve your problem.