Razor复选框在ASP.Net Core 2.2 MVC中始终返回false

Question

I have a checkbox field in my form. when the form is edited and re-submitted, the value for the checkbox always passed to the controller is false. I am using ASP.Net MVC Core 2.2.

Edit.cshtml

<form asp-action="Edit">
    <table>
    <tr>
        <td><label for="default">Default</label></td>
        <td>@Html.CheckBoxFor(m => m.IsDefault, new { @checked = "checked", @class = "form-input-styled" })</td>
    </tr>
    <tr>
        <td><label for="standard">Standard</label></td>
        <td>@Html.CheckBoxFor(m => m.IsStandard, new { @checked = "checked", @class = "form-input-styled" })</td>
    </tr>
    <tr>
        <td><label for="emailed">Emailed</label></td>
        <td>@Html.CheckBoxFor(m => m.IsEmailed, new { @checked = "checked", @class = "form-input-styled" })</td>
    </tr>
    </table>
</form>

ViewModel.cs

public class ReprintEditViewModel
{
    public bool IsDefault { get; set; }
    public bool IsStandard { get; set; }
    public bool IsEmailed { get; set; }
}

Controller.cs

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(int id, [Bind("Id,Date,PolicyNumber,OwnerName,SendTo,EmailAddress,ModifiedDate,LastModifiedBy,DeliveryMethod, Default, Standard, Emailed")] ReprintEditViewModel xrCertReprint)
    {
        if (ModelState.IsValid)
        {
                //string dm = string.Join(", ", DeliveryMethod);
                string dm = "";
                if (xrCertReprint.IsDefault == true)
                    dm = "Default";
                if (xrCertReprint.IsStandard == true)
                    if (dm.Length > 1)
                        dm = dm + ", " + "Standard";
                    else
                        dm = "Standard";
                if (xrCertReprint.IsEmailed == true)
                    if (dm.Length > 1)
                        dm = dm + ", " + "Emailed";
                    else
                        dm = "Emailed";

            return RedirectToAction(nameof(Index));
        }
        return View(xrCertReprint);
    }

I have tried other solutions/ways listed in stackoverflow. Nothing worked out. I am not sure what I was doing wrong?

Answer 1

Currently you are using below code to bind the data:

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("Id,Date,PolicyNumber,OwnerName,SendTo,EmailAddress,ModifiedDate,LastModifiedBy,DeliveryMethod, Default, Standard, Emailed")] ReprintEditViewModel xrCertReprint)
{
    if (ModelState.IsValid)
    {
            //string dm = string.Join(", ", DeliveryMethod);
            string dm = "";
            if (xrCertReprint.IsDefault == true)
                dm = "Default";
            if (xrCertReprint.IsStandard == true)
                if (dm.Length > 1)
                    dm = dm + ", " + "Standard";
                else
                    dm = "Standard";
            if (xrCertReprint.IsEmailed == true)
                if (dm.Length > 1)
                    dm = dm + ", " + "Emailed";
                else
                    dm = "Emailed";

        return RedirectToAction(nameof(Index));
    }
    return View(xrCertReprint);
}

While your model ReprintEditViewModel has properties IsDefault , IsStandard and IsEmailed which are not included in Bind attribute. So MVC model binder will ignore those properties and bind only the properties passed in attribute. If you remove the Bind attribute then all the properties having same name as in Model will bind because of MVC default model binder and you will get the values.

You can learn more about model binding using this link

Answer 2

The reason is that your [Bind] attribute does not include correct properties' names.

[Bind] attribute specifies which properties of a model should be included in model binding.

Change to use IsDefault, IsStandard, IsEmailed instead of Default, Standard, Emailed

 [HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("Id,Date,PolicyNumber,OwnerName,SendTo,EmailAddress,ModifiedDate,LastModifiedBy,DeliveryMethod, IsDefault, IsStandard, IsEmailed")] ReprintEditViewModel xrCertReprint)

Refer to https://docs.microsoft.com/en-us/aspnet/core/mvc/models/model-binding?view=aspnetcore-2.2#bind-attribute