[英]cascading dropdown razor pages
this is my code for cascading dropdown这是我的级联下拉代码
<div class="form-group col-md-4">
<label asp-for="CarChassis.CompanyNameId" class="control-label"></label>
<select asp-for="CarChassis.CompanyNameId" class="form-control" asp-items="ViewBag.CompanyNameId"></select>
<span asp-validation-for="CarChassis.CompanyNameId" class="text-danger"></span>
</div>
<div class="form-group col-md-4">
<label asp-for="CarChassis.CarModelId" class="control-label"></label>
<select asp-for="CarChassis.CarModelId" class="form-control" asp-items="ViewBag.CarModelId"></select>
<span asp-validation-for="CarChassis.CarModelId" class="text-danger"></span>
</div>
and code behind和后面的代码
[BindProperty]
public CarChassis CarChassis { get; set; }
public int CarCompanyId { get; set; }
public SelectList CarModelsList { get; set; }
public async Task<IActionResult> OnGetAsync()
{
ViewData["CarModelId"] = new SelectList(_context.CarModels, "Id", "Name");
ViewData["CompanyNameId"] = new SelectList(_context.CompanyNames, "Id", "Name");
ViewData["CreateYearId"] = new SelectList(_context.CreateYears, "Id", "Name");
ViewData["DiversityId"] = new SelectList(_context.Diversity, "Id", "Name");
return Page();
}
public JsonResult OnGetCarMode(int CarCompanyI)
{
var CarModelsList = _context.CarModels.Where(x => x.CompanyNameId == CarCompanyI).ToListAsync();
return new JsonResult(CarModelsList);
}
also this is my Models这也是我的模特
public class CompanyName
{
public string Name { get; set; }
public DateTime CreateDate { get; set; }
public DateTime ModifyDate { get; set; }
public ICollection<CarModel> CarModels { get; set; }
}
public int Id { get; set; }
public string Name { get; set; }
public DateTime CreateDate { get; set; }
public DateTime ModifyDate { get; set; }
public int CompanyNameId { get; set; }
public CompanyName CompanyName { get; set; }
}
and this is my ajax code这是我的 ajax 代码
<script>
$(function () {
$("#CarChassis_CompanyNameId").on("change", function () {
var CarCompanyI = $(this).val();
$("#CarChassis_CarModelId").empty();
$("#CarChassis_CarModelId").append("<option value=''>select </option>");
$.getJSON(`?handler=CarMode&CarCompanyI=${CarCompanyI}`, (data) => {
$.each(data, function (i, item) {
$("#SubCategoryId").append("<option value='"+ item.id+ "'>" + item.name + "</option>");
});
});
});
});
</script>
after run my code I get this error运行我的代码后,我收到此错误
Uncaught TypeError: Cannot read property 'id' of null
未捕获的类型错误:无法读取 null 的属性“id”
There are two problem in your code.您的代码中有两个问题。
The first one is in your code(This is not an asynchronous method, ToListAsync
cannot be used ):第一个在您的代码中(这不是异步方法,不能使用
ToListAsync
):
var CarModelsList = _context.CarModels.Where(x => x.CompanyNameId == CarCompanyI).ToListAsync();
Change it to:将其更改为:
var CarModelsList = _context.CarModels.Where(x => x.CompanyNameId == CarCompanyI).ToList();
The second one is in your ajax( SubCategoryId
is not exist).第二个在您的 ajax 中(
SubCategoryId
不存在)。
$.each(data, function (i, item) {
$("#SubCategoryId").append("<option value='"+ item.id+ "'>" + item.name + "</option>");
});
Change it to:将其更改为:
$.each(data, function (i, item) {
$("#CarChassis_CarModelId").append("<option value='"+ item.id+ "'>" + item.name + "</option>");
});
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