如何将 htmlhelper 的值从表（视图）传递给控制器​​？

Question

I want to update only a single value from a row on click of the update button against a specific ID, the id is available at controller but the updated value field is not available so when I press the update button controller updated the database but store a null value in DB.

//View Code
<tbody>
        @foreach (var item in Model)
        {
            <tr>
                <td>
                    @Html.DisplayFor(m => item.Id)
                </td>
                <td>
                    @Html.DisplayFor(m => item.TagName)
                </td>
                <td>
                    @Html.DisplayFor(m => item.TagCategory)
                </td>
                    <td>
                     @Html.TextBoxFor(m => item.TagValue, new { htmlAttributes = new { @class = "form-control" } })
                    </td>
                <td>
                    @Html.ActionLink("Update", "Update", new { id = item.Id}, new { htmlAttributes = new { @class = "form-control" } })
                </td>
            </tr>
        }
    </tbody>
//Controller Code
 public ActionResult Update([Bind(Include = "Id,TagValue") ]Tag tags)
    {
        var data = db.Tags.Where(x => x.Id == tags.Id).FirstOrDefault();
        if (data!=null)
        {
            data.TagValue = tags.TagValue;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        return View();
    }

Answer 1

So right now your update button makes a GET request. The database is storing null because when you create the ActionLink you are not passing in the TagValue as a parameter because with GET requests the variables need to be passed in the url. You could add the TagValue as a parameter like this

@Html.ActionLink("Update", "Update", new { id = item.Id, TagValue = item.TagValue }, new { htmlAttributes = new { @class = "form-control" } })

I don't think this will work the way you want though because I am assuming you want the user to be able to change the value of TagValue and then hit update to save the value. What this solution does is it just grabs the original value of whatever TagValue is.

If you want to be able to edit the TagValue and then submit you could change your html to look like this

<tbody>
@foreach (var item in Model)
{
    <tr>
        <form action="@Url.Action("Update")" method="post">
            <td>
                @Html.HiddenFor(m => item.Id, new { @Name = "Id" })
                @Html.DisplayFor(m => item.Id)
            </td>
            <td>
                @Html.DisplayFor(m => item.TagName)
            </td>
            <td>
                @Html.DisplayFor(m => item.TagCategory)
            </td>
            <td>
                @Html.TextBoxFor(m => item.TagValue, new { @class = "form-control", @Name="TagValue"  })
            </td>
            <td>
                <input type="submit" value="Update" />
            </td>
        </form>
    </tr>
}

This will create a form for every Tag you have and then generate a POST request when you hit submit.

vikscool's comment is also another good solution you could use.

Answer 2

您只需要将您的视图与您发送和接收数据的表绑定，您可以使用Html Begin Forms 来完成