Html.DropDownList 三级联动

Models结构

ProductorBF

public class ProductorBF
{
private MyDbDataContext Context = new MyDbDataContext();

public List<Productor> Select()
{
return Context.Productor.ToList();
}

public Productor Select(string prod_code)
{
var query = Context.Productor.Where(c => c.Prod_Code == prod_code);
if (query.Count() > 0)
{
return query.First();
}
return null;
}

BrandBF

public class BrandBF
{
private MyDbDataContext Context = new MyDbDataContext();

public List<Brand> Select()
{
return Context.Brand.ToList();
}

public List<Brand> Select(string Prod_Code)
{
var query = Context.Brand.Where(c => c.Prod_Code == Prod_Code);
if (query.Count() > 0)
{
return query.ToList();
}
return null;
}

public bool SelectBool(string brandcode)
{
var query = Context.Brand.Where(p=>p.Brand_Code==brandcode);
if (query.Count()>0)
{
return true;
}
return false;
}
}

CarBF

public class CarBF
{
private MyDbDataContext Context = new MyDbDataContext();

public List<Car> Select()
{
return Context.Car.ToList();
}

public List<Car> Select(string Brand_Code)
{
var query = Context.Car.Where(c=>c.Brand==Brand_Code);
if (query.Count()>0)
{
return query.ToList();
}
return null;
}
}

控制器

public ActionResult Index()
{
List<Productor> listP = new ProductorBF().Select();
//参数：集合、列values值、显示的列、选取的显示值
SelectList listProd = new SelectList(listP,"Prod_Code","Prod_Name","p001");

List<Brand> listB = new BrandBF().Select();
SelectList listBrand = new SelectList(listB,"Brand_Code","Brand_Name");
ViewBag.Brands = listBrand;

List<Car> listC = new CarBF().Select();
SelectList listCar = new SelectList(listC,"Code","Name");
ViewBag.Cars = listCar;

return View(listProd);
}

[HttpPost]
public ActionResult Index(string prod,string brand,string car)
{
//prod厂家编号，每次提交过来的编号都是正确的。改变厂家提交（改变第二级车系提交）过来的prod都是正确的
List<Productor> listP = new ProductorBF().Select();
SelectList listProd = new SelectList(listP,"Prod_Code","Prod_Name",prod);

//根据正确的厂家编号prod查询出的车系也是正确的
//在下拉列表中定位车系，可以判断是否是改变了车系提交过来的数据。如果没有改变车系，提交，
//brand是上一次的旧数据，如果改变车系提交，提交过来的brand是新选取的数据
List<Brand> listB = new BrandBF().Select(prod);
var c = new BrandBF().SelectBool(brand) ? brand : listB[0].Brand_Code;
SelectList listBrand = new SelectList(listB, "Brand_Code", "Brand_Name", c);
ViewBag.Brands = listBrand;

//与上面情况相同，页面没有操作车系的情况下，车辆的查询按上面新查出的车系编号查询
//页面操作改变车系的情况下，按提交过来的车系编号查询
var b = listB.Exists(p => p.Brand_Code == brand) ? brand : listB[0].Brand_Code;

List<Car> listC = new CarBF().Select(b);
SelectList listCar = new SelectList(listC,"Code","Name",car );
ViewBag.Cars = listCar;

return View(listProd);
}

Views

<div>
@using(@Html.BeginForm("Index","Cars",FormMethod.Post))
{
@Html.DropDownList("prod", Model, new { onchange = "document.forms[0].submit()" })@*js方法，值发生变化触发，效果==Html中第一个表单中的‘submit’提交*@
@Html.DropDownList("brand",ViewBag.Brands as SelectList, new { οnchange="document.forms[0].submit()" })
@Html.DropDownList("car", ViewBag.Cars as SelectList)
}
</div>

效果

第一级厂家变化

第二级车系变化

转载于:https://www.cnblogs.com/happinesshappy/p/4634564.html

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