在每个SelectList项目上设置Selected = True不会影响呈现的ListBox [英] Setting Selected=True on each SelectList item does not affect rendered ListBox

问题描述

我整天都在忙这个，我正处于最后的障碍.基本上，我在其中一种表单上有一个多选列表，我在其中填充了数据库中的数据.我在模型中定义了一个小部件"属性作为选择列表.

I've been messing around with this one all day and I'm at the last hurdle. Basically I've got a multiple select list on one of my forms which I'm populating with data from my database. I've got a 'Widgets' property defined in my model as a selectlist.

然后在将数据库中的属性绑定到模型的部分中，我得到了linq表达式，该表达式将另一个表中的属性添加到我的选择列表中.一切正常，我可以使用结果正确发回.但是，如果我在linq语句中设置了selected = true属性，则另一端没有任何选择.所以我的问题是为什么?其他所有属性，例如id等都可以通过.

Then in the section where I bind properties from my database to my model, I've got linq expression which adds properties from another table to my selectlist. This is all working fine and I can use the result to correctly post back. However if I set the selected = true property in my linq statement nothing gets selected on the other end. So my question is why? All the other properties, id's etc.. are getting passed through fine.

我的模特:

[DisplayName("Article Id")]
public int ArticleId { get; set; }
[DisplayName("Article Title")]
public string ArticleTitle { get; set; }
[DisplayName("Article Body")]
public string ArticleBody { get; set; }
[DisplayName("Publish on Site")]
public bool Published { get; set; }
[DisplayName("Add to Featured Articles")]
public bool Featured { get; set; }
[DisplayName("Created Date")]
public DateTime CreatedDate { get; set; }
public int AuthorId { get; set; }
[DisplayName("Author")]
public string Author { get; set; }
[DisplayName("Modified Date")]
public Nullable<DateTime> ModifiedDate { get; set; }
public int OwnerId { get; set; }
public SelectList Widgets { get; set; }

我的控制器(Relevent位)

My Controller (Relevent bit)

ArticlesModel Obj = new ArticlesModel
{
    ArticleId = row.ArticleId,
    ArticleTitle = row.ArticleTitle,
    ArticleBody = row.ArticleBody,
    Featured = row.Featured,
    Published = row.Published,
    Widgets = new SelectList(db.Query("SELECT * FROM [Widgets]").Select(x => new SelectListItem { Text = x.WidgetName, Value = ((int)x.WidgetId).ToString(), Selected = true }), "Value", "Text")
};
Obj.SetGlobalProperties(this.ControllerContext.HttpContext.Application);
ViewData["Article"] = Obj;

最后是视图

@Html.ListBoxFor(m => m.Widgets, Model.Widgets, new { @class = "form-control", @style = "margin-left: -20px !important; width: 500px" })

真的很感谢这里的任何帮助-我整天都在拉头发，看上去很简单.

Would really appreciate any help here - I've been pulling my hair out all day with something that on the face of it seems quite simple.

预先感谢

推荐答案

我认为您不应将可用选项与所选选项混合使用.

I think you should not mix the available options with the selected options.

您需要添加另一个属性来保存选定的选项，并将可用选项的类型从 SelectList 更改为 SelectListItem [].

You need to add another property for saving the selected options and change the available options type from SelectList to SelectListItem[].

public SelectListItem[] Widgets { get; set; }
public int[] SelectedWidgets { get; set; } // depends on WidgetId type

将其更改为 SelectListItem [] .

Widgets = db.Query("SELECT * FROM [Widgets]")
    .Select(x => new SelectListItem
    { 
        Text = x.WidgetName, 
        Value = ((int)x.WidgetId).ToString(),
        Selected = true 
    })
    .ToArray()

html

@Html.ListBoxFor(m => m.SelectedWidgets, Model.Widgets)

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