ASP MVC 4：DropDownListFor的请求值 [英] ASP MVC 4: Request value of DropDownListFor

问题描述

我有两个类多到很多，首先是Anuncios，第二个SubCategorias

I have two classes many-to-many the first is "Anuncios" and the second "SubCategorias"

public class Anuncios {
    public int AnuncioId {get;set;}
    public string Titulo {get;set;}
    public ICollection<SubCategorias> SubCategorias {get;set;}
}

public class SubCategorias {
    public int SubCategoriaId {get;set;}
    public string Nome {get;set;}
    public ICollection<Anuncios> Anuncios {get;set;}
}

在DAL层我做的方法保存在DB的Anuncio。

In DAL layer I did method to save the "Anuncio" in DB.

public void Salvar(Anuncio entidade)  {
     entidade.SubCategorias = entidade.SubCategorias.Select(subcat => _contexto.SubCategorias.FirstOrDefault(x => x.SubCategoriaId == subcat.SubCategoriaId)).ToList();
     _contexto.Anuncios.Add(entidade);
     _contexto.SaveChanges();
}

我创建行动创建

private readonly Context _ctx = new Context();

public ActionResult Create()
{
    var model = new Anuncios {SubCategorias = _ctx.SubCategorias.ToList()};
    return View(model);
}

在查看我做的DropDownList与SubCategorias

In View I made DropDownList with "SubCategorias":

@Html.LabelFor(model => model.SubCategorias)
@Html.DropDownListFor(model => model.SubCategorias, new SelectList(Model.SubCategorias, "SubCategoriaId", "Nome"))

该DropDownListFor填充了sucess ..

The DropDownListFor is populated with sucess..

精细....

但是，当提交形成DropDownListFor选择的值不会传递给方法创建。该anuncio.SubCategorias为空！

But when submit form the value selected in DropDownListFor not pass to method Create. The anuncio.SubCategorias is null!

private readonly AnunciosDal _anuncio = new AnunciosDal();

[HttpPost]
public ActionResult Create(Anuncio anuncio)
{
    _anuncio.Salvar(anuncio);
    return View(anuncio);
}

我在各种论坛上寻求解决方案，但没有找到

I have sought in various forums the solution, but could not find

有人帮我？！

对不起我的英语RS ...

Sorry about my english rs...

感谢您！
法布里西奥·奥利维拉

Thank You! Fabrício Oliveira

推荐答案

DropDownListFor的第一个参数必须保持的所选值，其中第二个参数包含列表中的对象：

The first parameter of DropDownListFor needs to be the object holding the selected value, where the second parameter contains the list:

@Html.DropDownListFor(model => model.SOME_ID_FOR_SELECTED_VALUE, 
                  new SelectList(Model.SubCategorias, "SubCategoriaId", "Nome"))

目前你还例如映射同一列表的第一个属性。你应该使用一个ID喜欢@Maess建议，然后通过绑定：

Currently the example you have also maps the same list as the first property. You should use an ID like @Maess suggested, and then bind it via:

@Html.DropDownListFor(model => model.SubCategoriaID, new SelectList(Model.SubCategorias, "SubCategoriaId", "Nome"))

选择数值，然后将它张贴回服务器这个领域SubCategoriaID

Selecting a value will then post it back to the server to this SubCategoriaID field.

这篇关于ASP MVC 4：DropDownListFor的请求值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！