Entity FrameWork (ORM) and DropDownList Html

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Entity FrameWork (ORM) and DropDownList Html

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#1 by (3 votes)

1

I have two mapped models that will work like this: The model Afaze will have a ComboBox (DropDownList) that will make the categories available to the user to select, however these categories are registered by the same, so in the source I have something like this:

 public class Afazer
{
    public int Id { get; set; }

    [Required(ErrorMessage = "Digite a titulo!")]
    [MinLength(1, ErrorMessage = "O tamanho mínimo da titulo são 1 caracteres.")]
    [StringLength(30, ErrorMessage = "O tamanho máximo são 30 caracteres.")]
    [Display(Name = "Titulo: ")]
    public string AFZ_TITULO { get; set; }

    [Required(ErrorMessage = "Digite a descrição!")]
    [MinLength(5, ErrorMessage = "O tamanho mínimo da descrição são 5 caracteres.")]
    [StringLength(256, ErrorMessage = "O tamanho máximo são 256 caracteres.")]
    [Display(Name = "Descrição: ")]
    public string AFZ_DESCRICAO { get; set; }

    [Display(Name = "Nivel de Prioridade")]
    [Range(1, int.MaxValue, ErrorMessage = "Selecione um Nivel valido!")]
    public Prioridades AFZ_NIVEL { get; set; }

    [Display(Name = "Categoria: ")]
    public virtual ICollection<Categorias> Categoria { get; set; }

    [Display(Name = "Status: ")]
    public bool AFZ_DONE { get; set; }

    [Browsable(false)]
    public string ApplicationUserId { get; set; }


}


 public class Categorias
{
    public int Id { get; set; }
    [Required(ErrorMessage = "Digite a categoria!")]
    [MinLength(1, ErrorMessage = "O tamanho mínimo da categoria são 1 caracteres.")]
    [StringLength(15, ErrorMessage = "O tamanho máximo são 15 caracteres.")]
    [Display(Name = "Titulo: ")]
    public string CAT_DESCRICAO { get; set; }
    public string ApplicationUserId { get; set; }


}

In my view I tried something like this: ( But it does not work )

@model Teste.Models.Afazer

@{
    ViewBag.Title = "Create";
}

<h2>Create</h2>


@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()
    
    <div class="form-horizontal">
        <h4>Afazer</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
 <div class="form-group">
            @Html.LabelFor(model => model.Categoria, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("CAT_DESCRICAO", new SelectList(Model.Categoria.AsEnumerable()))
                @Html.ValidationMessageFor(model => model.Categoria, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

c# entity-framework asp.net-mvc

asked by anonymous 24.09.2016 / 00:42

1 answer

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score 3 · Accepted Answer

I hope I can help you.

Look at the image below, you may notice that the second parameter is of type IEnumerable<SelectListItem> , however you are passing a IEnumerable<Categorias> .

So,youshouldchangethereinyourAfarámodelthe

publicvirtualICollection<Categorias>Categoria{get;set;}

for

publicvirtualICollection<SelectListItem>Categoria{get;set;}

Then,youmustaddanewfieldinyourAfazermodeltosavetheselectedvalue.Assumingyou'dliketosavetheIdofyourCategory,addthefollowingfieldintheAfazermodel:

publicstringIdCategoria{get;set;}

Thenyoushouldmodifyyourviewtolooklikethis:

@Html.DropDownList("IdCategoria", Model.Categoria)

The first parameter is the field of your Afará form that will be populated when selecting any category.

Finally, in your Action , add as a return a new instance of your model, already populating your IEnumerable , like this:

public virtual ActionResult Index() {
     return View("Index", new Afazer {
           Categoria = new[] {
               new SelectListItem { Text = "Categoria 1", Value = "1" },
               new SelectListItem { Text = "Categoria 2", Value = "2" },
           }
     });
}

Okay, now your dropdown will be working. Any questions are available.

Some tips:

I have some tips for your code, however this is only by convention, it does not have to be followed.

Class names always in the singular, in your case, the class should be called Category ;

Property names of the IEnumerable , ICollection types and etc, always in the plural, in your case, the Category property in the Afazer model should be called Categories ;

Model names should contain the word Model in the end, in your case it would be AfazerModel , or better yet, to say that it is a model linked to a View , leave the name as AfazerViewModel ;

Remembering that this is just by convention, for better written code, it does not have to be followed

Well, that's it. Hope this helps. Thanks!