[英]How to get the values of the checked items of checkboxes in MVC5?
I have a view model which includes an ICollection field, something like this: 我有一个包含ICollection字段的视图模型,如下所示:
public class BusinessViewModel
{
...
public virtual ICollection<Subcategory> Subcategories { get; set; }
...
}
Then, in my actual view, I have a code segment like this: 然后,在我的实际视图中,我有一个如下代码段:
<div class="form-group">
@Html.LabelFor(model => model.Subcategories, "Subcategory", htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<span id="subcats">
</span>
</div>
</div>
Afterwards, I have an AJAX call in JS, which simply populates my subcats span field with checkbox items, and my AJAX call looks like this: 之后,我在JS中进行了AJAX调用,该调用仅用复选框项目填充了subcat的span字段,而我的AJAX调用如下所示:
$("#CategoryID").change(function () {
$("#subcats").empty();
$.ajax({
type: 'POST',
url: '/Account/GetSubcategories',
dataType: 'json',
data: { id: $("#CategoryID").val() },
success: function (subcategories) {
$.each(subcategories, function (i, subcategory) {
$("#subcats").append('<input type="checkbox" name="' + subcategory.value + '" value="' + subcategory.id + '" />' + subcategory.value + '<br />');
});
},
error: function (ex) {
console.log('Failed to retrieve subcategories! ' + ex);
}
});
return false;
});
The point is that, it works all fine in the view, but when I check the items I wish and press the button in order to submit the form, I get an error message saying that a NullReferenceException occurred, when I reach the foreach statement of the below code in my controller: 关键是,它在视图中一切正常,但是当我检查希望的项目并按下按钮以提交表单时,我收到一条错误消息,指出当我到达foreach语句时,发生了NullReferenceException。我的控制器中的以下代码:
public async Task<ActionResult> RegisterBusiness(BusinessViewModel model)
{
if (ModelState.IsValid)
{
...
foreach (var subcategory in model.Subcategories)
{
db.Entry(subcategory).State = EntityState.Unchanged;
user.Subcategories.Add(subcategory);
}
...
}
...
}
I guess this is due to the fact I don't assign the selected checkboxes to my model. 我猜这是由于我没有将选定的复选框分配给我的模型。 Can someone, tell me how can I do it in my current setup?
有人可以告诉我如何在当前设置中进行操作吗? A code example where this is achieved would be highly welcomed.
一个实现此目标的代码示例将受到高度欢迎。
EDIT: This is how my subcategory model looks like, at least important part of it: 编辑:这是我的子类别模型的样子,至少是其中的重要部分:
public class Subcategory
{
public int SubcategoryID { get; set; }
public string SubcategoryName { get; set; }
}
And also according to the answer below my view now includes this: 而且根据下面的答案,我的观点现在包括:
<div class="form-group">
@Html.LabelFor(model => model.Subcategories, "Subcategory", htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.ListBoxFor(model => model.SelectedSubcategories, Model.SubcategoryList)
</div>
</div>
I get a NullReference error again in the ListBoxFor part. 我在ListBoxFor部分中再次收到NullReference错误。
Your SubCategories
are null because you are not posting back an values relating to SubCategories
. 您的
SubCategories
为空,因为您没有回发与SubCategories
相关的值。 The following example is based on using a multi-select list to choose the sub categories (unchecked checkboxes do not post back, so using checkboxes is much more difficult) 以下示例基于使用多选列表来选择子类别(未选中的复选框不会回发,因此使用复选框要困难得多)
First create a property in you view model that binds to the selected sub categories. 首先,在视图模型中创建绑定到所选子类别的属性。 You may also want a
SelectList
property to render the initial sub categories to display 您可能还希望
SelectList
属性呈现要显示的初始子类别
public int[] SelectedSubCategories { get; set; }
public SelectList SubCategoryList { get; set; }
and in the view, render the select 然后在视图中渲染选择
@Html.ListBoxFor(m => m.SelectedSubCategories, Model.SubCategoryList)
then modify your script 然后修改您的脚本
$("#CategoryID").change(function () {
$("#SelectedSubCategories").empty();
var url = '@Url.Action("GetSubcategories", "Account")';
$.get(url, { id: $("#CategoryID").val() }, function(subcategories) {
$.each(subcategories, function (i, subcategory) {
var option = $('<option></option>');
option.val(subcategory.id);
option.text(subcategory.value);
$("#SelectedSubCategories").append(option);
});
});
});
When posting back, the value of SelectedSubCategories
now contains the ID's of each selected sub category 回发时,
SelectedSubCategories
的值现在包含每个选定子类别的ID
public async Task<ActionResult> RegisterBusiness(BusinessViewModel model)
{
foreach (int ID in model.SelectedSubCategories)
{
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.