在 ASP.NET-MVC 中使用 RedirectToAction 传递字符串类型列表

Question

此代码用于传递List<String>withRedirectToAction方法：public List<String> ListOfBrandNames(string id)    {        var result = db.Items.Where(x => x.Category.Name.Equals(id)).Select(x => x.BrandID).ToList();        var ListOfBrands = db.Brands.Where(t => result.Contains(t.BrandID)).ToList();        List<String> BrandNames = ListOfBrands.Select(f => f.Name.ToString()).ToList();        return RedirectToAction("BrandsOfACategory", new { brands = BrandNames });    }RedirectToAction方法抛出此错误：无法将类型“System.Web.Mvc.RedirectToRootResult”隐式转换为“System.Collection.Generic.List”

Answer 1

您在操作方法上使用了错误的返回类型，因为RedirectToAction需要返回类型ActionResult而不是List<string>因为RedirectToRouteResult继承自ActionResult.

更新：

您需要将列表序列化为 JSON 字符串才能顺利传递（带Newtonsoft.Json库），因此目标操作方法必须使用string参数。这是将品牌列表发送到另一个操作方法的正确设置：

public ActionResult ListOfBrandNames(string id)

{

    var result = db.Items.Where(x => x.Category.Name.Equals(id)).Select(x => x.BrandID).ToList();

    var ListOfBrands = db.Brands.Where(t => result.Contains(t.BrandID)).ToList();

    return RedirectToAction("BrandsOfACategory", new { brands = JsonConvert.SerializeObject(ListOfBrands) });

}

目标控制器动作应该是这样的：

[HttpGet]

public ActionResult BrandsOfACategory(string brands)

{

    var listOfBrands = JsonConvert.DeserializeObject<List<Brand>>(brands);

    List<string> BrandNames = listOfBrands.Select(f => f.Name.ToString()).ToList();

    // do something and return view

}

Answer 2

试试下面的代码，

public List<String> ListOfBrandNames(string id)

{

    var result = db.Items.Where(x => x.Category.Name.Equals(id)).Select(x => x.BrandID).ToList();

    var ListOfBrands = db.Brands.Where(t => result.Contains(t.BrandID)).ToList();

    List<String> BrandNames = ListOfBrands.Select(f => f.Name.ToString()).ToList();

    TempData["Brands"]=BrandNames;

    return RedirectToAction("BrandsOfACategory");

}

之后，您可以从 TempData 获取数据到“BrandsOfACategory”方法中的字符串列表。