asp.net mvc @Html.CheckBoxFor

问题:

I have checkboxes in my form

I added at my model

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;

 namespace CorePartners_Site2.Models
 {
public class CareerForm
     {
    //....
    public List<CheckBoxes> EmploymentType { get; set; } 
      }
 }

 public class CheckBoxes
 {
     public string Text { get; set; }
     public bool Checked { get; set; }
 }

and added at my form

@Html.CheckBoxFor(model => model.EmploymentType, new { id = "employmentType_1" })
@Html.CheckBoxFor(model => model.EmploymentType, new { id = "employmentType_2" })
@Html.CheckBoxFor(model => model.EmploymentType, new { id = "employmentType_3" })

but I get the mistake

What's wrong?

回答1:

CheckBoxFor takes a bool, you're passing a List<CheckBoxes> to it. You'd need to do:

@for (int i = 0; i < Model.EmploymentType.Count; i++)
{
    @Html.CheckBoxFor(m => m.EmploymentType[i].Checked, new { id = "employmentType_" + i })
    @Html.HiddenFor(m => m.EmploymentType[i].Text)
    @Html.DisplayFor(m => m.EmploymentType[i].Text)
}

Notice I've added a HiddenFor for the Text property too, otherwise you'd lose that when you posted the form, so you wouldn't know which items you'd checked.

Edit, as shown in your comments, your EmploymentType list is null when the view is served. You'll need to populate that too, by doing this in your action method:

public ActionResult YourActionMethod()
{
    CareerForm model = new CareerForm();

    model.EmploymentType = new List<CheckBox>
    {
        new CheckBox { Text = "Fulltime" },
        new CheckBox { Text = "Partly" },
        new CheckBox { Text = "Contract" }
    };

    return View(model);
}

回答2:

Html.CheckBoxFor expects a Func<TModel, bool> as the first parameter. Therefore your lambda must return a bool, you are currently returning an instance of List<Checkboxes>:

model => model.EmploymentType

You need to iterate over the List<Checkboxes> to output each checkbox:

@for (int i = 0; i < Model.EmploymentType.Count; i++)
{
    @Html.HiddenFor(m => m.EmploymentType[i].Text)
    @Html.CheckBoxFor(m => m.EmploymentType[i].Checked, 
              new { id = string.Format("employmentType_{0}", i) })
}

回答3:

Use this code:

@for (int i = 0; i < Model.EmploymentType.Count; i++)
{
    @Html.HiddenFor(m => m.EmploymentType[i].Text)
    @Html.CheckBoxFor(m => m.EmploymentType[i].Checked, new { id = "YourId" })
}

回答4:

If only one checkbox should be checked in the same time use RadioButtonFor instead:

      @Html.RadioButtonFor(model => model.Type,1, new { @checked = "checked" }) fultime
      @Html.RadioButtonFor(model => model.Type,2) party
      @Html.RadioButtonFor(model => model.Type,3) next option...

If one more one could be checked in the same time use excellent extension: CheckBoxListFor:

Hope,it will help