我有这个按钮，当单击该按钮时，将创建一个包含多个下拉列表的新div行。如何从加载到我的视图的viewmodel中填充这些下拉菜单？
@model App.Data.ViewModels.FilterDocumentsViewModel
<button type="button" class="btn btn-outline-secondary" data-toggle="collapse" data-target="#datatable-search-input-container-rowtwo" aria-expanded="false" aria-controls="datatable-search-input-container-rowtwo">
<i class="fa fa-plus"></i>
</button>
$("#datatable-search-input-container-rowone-coltwo").on("click", "#add-row", function (e) {
var htmlElements = "<div class='col-sm-10 row'>";
htmlElements = htmlElements + "<div class='col-sm-3 search-spacing'>";
htmlElements = htmlElements + "<label>Document Categories</label>";
htmlElements = htmlElements + "<select class='form-control' name='CategoryId[]' asp-items='@Model.Categories'>Select Category</select>"
htmlElements = htmlElements + "<label>Document Fields</label>";
htmlElements = htmlElements + "<select class='form-control' name='FieldId[]' asp-items='@Model.DocumentFields'>Select Document Fields</select>"
htmlElements = htmlElements + "</div>";
htmlElements = htmlElements + "</div>";
$(htmlElements).appendTo("#datatable-search-input-container-rowone-colone-sub");
return false;
});
我上面的内容只创建了一个空的下拉列表。另外，是否可以对文档类别进行一次更改，以重新填充文档字段？
编辑：根据@TetsuyaYamamotos的回答，这是我所做的
PartialView：
@model App.Data.ViewModels.FilterDocumentsViewModel
<div class="col-sm-12 row">
<div class="col-sm-3 search-spacing">
<label>Document Categories</label>
@Html.DropDownListFor(m => m.CategoryId, (SelectList)Model.Categories, "Select Category", new { @class = "form-control Categories" })
</div>
<div class="col-sm-3 search-spacing">
<label>Document Fields</label>
@Html.DropDownListFor(m => m.FieldId, (SelectList)Model.DocumentFields, "Select Field", new { @class = "form-control Fields" })
</div>
<div class="col-sm-3 search-spacing">
<label for="Data">Data</label>
<input type="text" id="Data" placeholder="Search" />
</div>
</div>
jQuery：
function refreshDropdown(Input) {
$.ajax({
url: "@Url.Action("GetFields", @ViewContext.RouteData.Values["controller"].ToString())",
method: "POST",
data: JSON.stringify(Input),
contentType: "application/json",
success: function (result) {
$(".Fields").empty();
$(".Fields").append("<option value>Select Field</option>");
$.each(result.fields, function (key, value) {
$(".Fields").append("<option value="+value.Id+">"+value.Name+"</option>");
});
},
error: function (error) {
console.log(error);
}
});
}
$("#datatable-search-input-container").on("change", ".Categories", function (e) {
console.log("changed");
selected = $(".Categories").find(":selected").val();
var form_data = selected;
refreshDropdown(form_data);
return false;
});
添加行：
$("#datatable-search-input-container-rowone-coltwo").on("click", "#add-row", function (e) {
$.ajax({
url: "@Url.Action("AddSearchFilterRow", @ViewContext.RouteData.Values["controller"].ToString())",
method: "GET",
contentType: "application/json",
success: function (result) {
$(result).appendTo("#datatable-search-input-container-rowone-colone-sub");
},
error: function (error) {
console.log(error);
}
});
return false;
});
剩下的唯一问题是，唯一起作用的onchange是主要变量，而不是更改时添加的jquery
答案 0 :(得分：0)
您可以将数据从viewmodel获取到javascript对象中，并使用jquery遍历该数据
var modelCategories = @Html.Raw(Json.Encode(Model.Categories));
var modelDocumentFields =@Html.Raw(Json.Encode(Model.DocumentFields));
$("#datatable-search-input-container-rowone-coltwo").on("click", "#add-row", function (e) {
var htmlElements = "<div class='col-sm-10 row'>";
htmlElements = htmlElements + "<div class='col-sm-3 search-spacing'>";
htmlElements = htmlElements + "<label>Document Categories</label>";
htmlElements = htmlElements + "<select class='form-control' name='CategoryId[]'>;
htmlElements += "<option>Select Category</option>";
$.each(modelCategories, function(i,v){
htmlElements += `<option value="${v.CategoryId}">${v.CategoryName}</option>`
});
htmlElements = htmlElements + "</select>";
htmlElements = htmlElements + "<label>Document Fields</label>";
htmlElements = htmlElements + "<select class='form-control' name='FieldId[]'>;
htmlElements += "<option>Select Document Fields</option>";
$.each(modelCategories, function(i,v){
htmlElements += `<option value="${v.FieldId}">${v.FieldNameName}</option>`
});
htmlElements = htmlElements + "</select>";
htmlElements = htmlElements + "</div>";
htmlElements = htmlElements + "</div>";
$(htmlElements).appendTo("#datatable-search-input-container-rowone-colone-sub");
return false;
});
答案 1 :(得分：0)
ASP.NET Core MVC标记帮助程序的行为类似于@Html.DropDownListFor()帮助程序，它们都呈现在服务器端，应被视为asp-for服务器端属性。您需要使用包含要追加的元素的局部视图，并附带一个控制器操作方法来将其返回，如下例所示：
SelectPartialView.cshtml
@model App.Data.ViewModels.FilterDocumentsViewModel
<div class='col-sm-10 row'>
<div class='col-sm-3 search-spacing'>
<label>Document Categories</label>
<select class='form-control category' asp-for='CategoryId' asp-items='@Model.Categories'>Select Category</select>
<label>Document Fields</label>
<select class='form-control field' asp-for='FieldId' asp-items='@Model.DocumentFields'>Select Document Fields</select>
</div>
</div>
控制器操作
public IActionResult GetSelectList()
{
// do something
return PartialView("SelectPartialView");
}
然后使用AJAX回调将部分视图元素附加到目标元素中：
$("#datatable-search-input-container-rowone-coltwo").on("click", "#add-row", function (e) {
$.get('@Url.Action("GetSelectList", "ControllerName")', function (result) {
$("#datatable-search-input-container-rowone-colone-sub").append(result);
});
});
关于级联<select>标签助手，您需要在两个下拉列表中定义class选择器，并使用AJAX填充选项列表：
$('.category').on('change', function() {
$.ajax({
type: 'GET',
url: '@Url.Action("GetFields", "ControllerName")',
data: { CategoryId: $(this).val() },
success: function (result) {
$('.field').empty();
$.each(result, function (i, item) {
// replace 'item.Value' and 'item.Text' from corresponding list properties into model class
$('.field').append('<option value="' + item.Value + '"> ' + item.Text + ' </option>');
});
},
error: function (xhr, status, err) {
// error handling
}
});
});
控制器操作
public IActionResult GetFields(int CategoryId)
{
// populate SelectListItem here
return new JsonResult(list);
}
级联<select>元素的另一个示例可以在这里找到：