如何使用 entity framework 或 MVC 项目绑定 HTML select 元素？

Question

我当前的项目是基于 MVC 的。我坚持尝试从我的 SQL 服务器数据库 table 填充 select 元素。控制器正在 DataTable 对象中接收数据库数据。此数据需要在页面加载时绑定到 HTML select 元素。

如有任何帮助，我们将不胜感激。

控制器代码 GET 方法操作

 // GET: SearchPopulate
 [HttpGet]
 public ActionResult SearchHome()
 {
        SearchPopulateMaster empPopulate = new SearchPopulateMaster();
        empPopulate.emp = PopulateEmps();
        return View();
 }

 private static List<SelectListItem> PopulateEmps() 
 {
        List<SelectListItem> items = new List<SelectListItem>();
        DataTable localdt = new DataTable();
        localdt = DALAcess.getDataFromSql("SELECT id,AgentName from [atmcolle_COMM_U88].[dbo].ATM_M_empMaster");
        return items;
 }

查看代码 .cshtml 文件

<form asp-controller="SearchHome" asp-action="SearchHome">
    <!--Non-hardcoded retrieved from database-->
    <select name="selEmp" id="selEmp">
        <option>Please select one</option>
    </select>

    <input type="submit" />
    <!--Non-hardcoded retrieved from database-->
</form>

Answer 1

您似乎正试图将您的 Data 绑定到 HTML dropdown (HTML Select Tag) 中，后者使用来自您数据库的 entity framework。

您可以尝试以下步骤：

Model:

假设我有这样的模型：

public class Agent
    {
        [Key]
        public int Id { get; set; }
        public string AgentName { get; set; }
    }

Controller:

    public ActionResult BindHtmlSelectElement()
    {
        //Bind Dropdown
        List<Agent> agent = PopulateEmps();
        ViewBag.Agent = new SelectList(agent, "Id", "AgentName");
        return View();
    }

View:

   @model MVCApps.Models.Agent
    @{
        ViewData["Title"] = "BindHtmlSelectElement";
    }
    
    <h4><strong>BindHtmlSelectElement</strong> </h4>
    <hr />
    <div class="form-group">
        <label  class="control-label col-md-2">Agent</label>
        <div class="col-md-10">
            <select asp-items="ViewBag.Agent" value=""  class="form-control" asp-for="Id"></select>
        </div>
    </div>

Output:

Note: In your PopulateEmps method return your agent list. And be conscious about the convension as well I made the id as Id be carefull while replace that to get rid of any error.

Update: 您也可以尝试访问您的 Agent 查询，如下所示

public List<Agent> QueryBuilder()
        {
            using (var connection = new SqlConnection("Server=ServerName;Database=YouDatabaseName;Trusted_Connection=True;MultipleActiveResultSets=true"))
            {

                List<Agent> viewModeList = new List<Agent>();
                await connection.OpenAsync();
                var command = connection.CreateCommand();
                command.CommandText = "SELECT id,AgentName from [atmcolle_COMM_U88].[dbo].ATM_M_empMaster";
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    Agent viewModel = new Agent();
                    viewModel.Id= reader["id"].ToString(); // Remember to convert property in correct format
                    viewModel.AgentName = reader["AgentName"].ToString();
                    viewModeList.Add(viewModel);

                }
                reader.Close();
                command.Dispose();
                connection.Close();
                return viewModeList;
            }

        }

Update The Controller Like Below:

public ActionResult BindHtmlSelectElement()
    {
        //Bind Dropdown
        List<Agent> agent = QueryBuilder();
        ViewBag.Agent = new SelectList(agent, "Id", "AgentName");
        return View();
    }

希望以上步骤能指导您实现目标。