问题描述
我正在尝试使用下拉列表过滤表,但在 ASP.NET Core 中提交表单后,我无法保持 SelectListItem 值处于选中状态。
过滤器似乎有效,但每当页面重新加载所选项目时总是相同的
获取控制器
public ActionResult Index(int myDropDown)
{
var myItems= new List<Items>();
myItems = _myRepository.GetAllItems();
var filteredItems = myItems.Where(x => x.Color.DemoId == myDropDown);
if (myDropDown != 0 )
{
return View(filteredItems);
}
return View(myItems);
}
Index.chtml
<form asp-controller="MyController">
<div class="row">
<div class="form-group col-3">
<select class="form-control" id="exampleFormControlSelect1" name="myDropDown"
asp-items="(_myRepository.GetDemos()).Select(x => new SelectListItem()
{ Text = x.Name,Value = x.Id.ToString()})" onchange="this.form.submit()">
</select>
</div>
</form>
C# 方法
public List<Demo> GetDemos()
{
var demos = _dbContext.Demos.Select(x => new Demo()
{
Id = x.Id,Name = x.Name
}).ToList();
return demos;
}
解决方法
尝试使用下拉列表过滤表格,但在提交表单后我无法保持 SelectListItem 值处于选中状态
您可以尝试动态设置 Selected
的 SelectListItem
属性,如下所示。
<select class="form-control" id="exampleFormControlSelect1" name="myDropDown"
asp-items="(_myRepository.GetDemos()).Select(x => new SelectListItem()
{ Text = x.Name,Value = x.Id.ToString(),Selected = x.Id == ViewBag.SelectedIndex ? true : false })" onchange="this.form.submit()">
</select>
实战方法
public ActionResult Index(int myDropDown)
{
var myItems = new List<Items>();
myItems = _myRepository.GetAllItems();
var filteredItems = myItems.Where(x => x.Color.DemoId == myDropDown);
//pass selected value through ViewBag etc
ViewBag.SelectedIndex = myDropDown;
if (myDropDown != 0)
{
return View(filteredItems);
}
return View(myItems);
}