Question

我的目标是从数据库中获取位置列表（即＆＃34; sites＆＃34;）并使用ViewComponent在_Layout的下拉列表（html select元素）中显示它们，但是我收到以下错误：

＆＃34;无法隐式转换类型＆＃39; System.Collections.Generic.List＆＃39;至＆＃39; Microsoft.AspNetCore.Mvc.IViewComponentResult＆＃39 ;.一个明确的转换是否存在（您是否错过了演员表？）＆＃34;

查看组件类[SiteID.cs] （PortalContext是我的DbContext）

namespace XX.Views.Shared.Components
{
    [ViewComponent(Name = "SiteIDsDropDown")]
    public class SiteIDsDropDownViewComponent : ViewComponent
    {
        private ILogger logger;
        private PortalContext context;

    public IViewComponentResult Invoke(ILogger<SecureController> logger, PortalContext context)
    {
        var _logger = logger;
        var _context = context;

        var results = (from s in _context.Sites
                        select new SiteViewModel
                        {
                            ID = s.ID,
                            Description = s.Description
                        }).ToList();
        return results;
    } 
}

查看组件部分视图[〜/ Views / Shared / Component / SiteIDsDropDownViewComponent / default.cshtml]

@model IEnumerable<XX.ViewModels.SiteIDViewModel>     
<select>
    <option>Please select and item</option>
    @foreach (var item in Model)
    {
        <option>@item.ID</option>
    }
</select>

Answer 1

返回结果应该是View（结果），所以相应地改变你的方法。

public IViewComponentResult Invoke(ILogger<SecureController> logger, PortalContext context)
{
    var _logger = logger;
    var _context = context;

    var results = (from s in _context.Sites
                    select new SiteViewModel
                    {
                        ID = s.ID,
                        Description = s.Description
                    }).ToList();
    return View(results);
}

将IEnumerable结果传递给ViewComponent中的下拉列表

1 个答案: