使用asp.net MVC中的下拉列表进行搜索

Question

I'm new to ASP.NET MVC. I want to use selected items from my dropdownlist to search my database table. The dropdownlist was generated from a BOL model which automatically binds to the view.

Below are my code snippet

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using BLL;
using BOL;

namespace DentiCareApp.Areas.Admin.Controllers
{
    [AllowAnonymous]
    public class GenerateInvoiceController : Controller
    {
        private TreatmentBs objBs;

        public GenerateInvoiceController()
        {
                objBs = new TreatmentBs();
        }
        // GET: Admin/GenerateInvoice
        public ActionResult Index(string CompanyID)
        {
            DentiCareEntities db = new DentiCareEntities();
            ViewBag.CompanyId = new SelectList(db.Companies, "CompanyId", "CompanyName");

            if (CompanyID == null)
            {
                return View();
            }
            else
            {
                return View(db.Treatments.Where(x => x.Company == CompanyID.Take(50)));
            }
            //return View();
        }

Also below is the interface of view.

Secondly, I also want the search result to appear on the same page. How do I do this? If I create a separate action for this, I will need to create a separate view for it. Can partial view be used? If so how?

Below is the code to the View

    @model BOL.GenerateInvoice
    @{
        ViewBag.Title = "Index";
        Layout = "~/Views/Shared/_Layout.cshtml";
    }
    <p></p>
    <p></p>
    <p></p>
    <h2>Quickly Generate Invoice</h2>
    @using (Html.BeginForm("Index", "GenerateInvoice", FormMethod.Get))
    {
        @Html.AntiForgeryToken()
        <div class="">
            <div>
                @Html.DropDownList("MyCompany.CompanyId", (IEnumerable<SelectListItem>)ViewBag.CompanyId, "Select Company", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.MyCompany.CompanyId, "", new { @class = "text-danger" })
                <input type="submit" value="Search" class="btn btn-primary" />
            </div>
        </div>
    }

Answer 1

Try this.

Controller action :

public ActionResult Index(string CompanyID)
{
    DentiCareEntities db = new DentiCareEntities();
    ViewBag.CompanyId = new SelectList(db.Companies, "CompanyId", "CompanyName", CompanyID);    // preselect item in selectlist by CompanyID param

    if (!String.IsNullOrWhiteSpace(CompanyID))
    {
        return View();
    }

    return View(db.Treatments.Where(x => x.CompanyID == CompanyID).Take(50));
}

View code :

@model IEnumerable<Treatment>

@{
    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Quickly Generate Invoice</h2>

@using (Html.BeginForm("Index", "GenerateInvoice", FormMethod.Get))
{
    @Html.AntiForgeryToken()

    @Html.DropDownList("CompanyId", (SelectList)ViewBag.CompanyId, "Select Company", new { @class = "form-control" })
    <input type="submit" value="Search" class="btn btn-primary" />
}

@if(Model != null && Model.Any())
{
    foreach(var item in Model)
    {
        @Html.DisplayFor(model => item)
    }
}

You can change the DisplayFor() here to show individual properties of the given Treatment, such as @Html.DisplayFor(model => model.TreatmentID) and such

Answer 2

The Above code worked for me but with little tweaks. Here are few modification I made to your code.

1. The parameter in the Index Action was changed from string to integer .
2. The Optional Parameter in the ViewBag.CompanyId was removed.
3. Lastly, the line if (!String.IsNullOrWhiteSpace(CompanyID)) and changed to if (CompanyID == 0) { return View(treatmentList);}

The result however is great as it worked like a charm! Thanks for your help!

        // GET: Admin/ListTreatment
        public ActionResult Index(string sortOrder, string sortBy, string Page, int CompanyID = 0)
        {
            ViewBag.sortOrder = sortOrder;
            ViewBag.sortBy = sortBy;

            var treatmentList = objBs.GetALL();

            //ViewBag.employeeCompany = employeeCompany.Distinct();
            switch (sortOrder)
            {
                case "Asc":
                    treatmentList = treatmentList.OrderBy(x => x.TreatmentDate).ToList();
                    break;
                case "Desc":
                    treatmentList = treatmentList.OrderByDescending(x => x.TreatmentDate).ToList();
                    break;
                default:
                    break;
            }

            ViewBag.CompanyId = new SelectList(db.Companies, "CompanyId", "CompanyName");

            ViewBag.TotalPages = Math.Ceiling(objBs.GetALL().Where(x=>x.CompanyId > 0).Count()/10.0);
            int page = int.Parse(Page == null ? "1" : Page);
            ViewBag.Page = page;

            treatmentList = treatmentList.Skip((page - 1) * 10).Take(10);

            if (CompanyID == 0)
            {
                return View(treatmentList);
            }

            return View(db.Treatments.Where(x => x.CompanyId == CompanyID).Take(50));
        }

Answer 3

• First : for entity framework id should be nullable, so it can be accepted as argument, the action parameter should be int? CompanyID int? CompanyID

• Second : the comparison is not correct with (CompanyID == 0)

  It should be (CompanyID == null)