[英]MVC Controller parameters not required but optional
嗨,我从视图中使用HttpPost将一些参数发送到控制器,数据库根据这些给定参数进行过滤。 但是参数应该是可选的,如果没有给出,控制器将忽略它们。 但这似乎不可能吗?
视图
@using (Html.BeginForm("Index", "Logbook")) {
@Html.ValidationSummary(true)
<div class="col-lg-3">
<div class="panel panel-default">
<div class="panel-heading">
<i class="fa fa-bell fa-fw"></i> Filter logbook
</div>
<div class="panel-body">
<div class="col-lg-5">
@Html.Label("Filter on room: ")
@Html.Label("Filter on date: ")
</div>
<div class="col-lg-6">
@Html.DropDownList("dropdownlist",Eindwerk.Controllers.RoomController.GetRooms(),new { @class = "btn btn-default-dropdown-toggle"})
@Html.TextBox("datepicker","", new { @class = "form-control" })
</div>
<div>
<button type="submit" class="btn btn-outline btn-primary btn-lg btn-block">Filter logbook</button>
@Html.ActionLink("Remove Filter", "Index","FilterClear",new { @class = "btn btn-outline btn-success btn-lg btn-block" })
</div>
}
CONTROLLER
我认为可以仅检查参数是否为null并相应地更改函数:
[HttpPost]
public ActionResult Index(string dropdownlist, DateTime datepicker)
{
if(dropdownlist != null && datepicker != null)
return View(db.Logbook.Where(p => p.Room == dropdownlist && p.Time.Day == datepicker.Month).OrderByDescending(a => a.Id).ToList());
if(dropdownlist != null && datepicker == null)
return View(db.Logbook.Where(p => p.Room == dropdownlist).OrderByDescending(a => a.Id).ToList());
if(dropdownlist == null && datepicker != null)
return View(db.Logbook.Where(p => p.Time.Day == datepicker.Month).OrderByDescending(a => a.Id).ToList());
else
return View(db.Logbook.OrderByDescending(p => p.Id).ToList());
}
但是我立即得到一个错误,应该给出参数,是否可以将这些参数设置为可选参数?
将参数声明为可为空
public ActionResult Index(string dropdownlist, DateTime? datepicker)
声明可为空的参数
public ActionResult Index(string? dropdownlist, DateTime? datepicker)
您可以通过将参数设置为可选参数并分配默认值null来解决此问题:
public ActionResult Index(string dropdownlist, DateTime? datepicker = null){}
试试这个可以工作
公共ActionResult索引(字符串dropdownlist = null,DateTime datepicker = null)
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