Question

我正在将.Net Core Razor Pages与ADO.Net一起使用。我正在尝试从数据库中提取数据并插入到下拉列表中。我得到这个

无法将类型'System.Collections.Generic.List '隐式转换为'System.Collections.Generic.IEnumerable '。存在显式转换（您是否缺少演员表？）

CommDept模型

[Table("CommDept")]
public class CommDept
{
    [Key]
    public int CommDeptID { get; set; }
    public string DeptText { get; set; }
    public SelectList DropDownList { get; set; }
}

Index.cshtml.cs

[BindProperty]
public List<CommDept> DropDownList { set; get; }

public void OnGet()
{
    var DropDownList = new List<CommDept>();

    using (SqlConnection conn = new SqlConnection(connectionString))
    using (SqlCommand cmd = new SqlCommand("SELECT CommDeptID, DeptText FROM CommDept", conn))
    {
        using (SqlDataReader rdr = cmd.ExecuteReader())
        {
            while (rdr.Read())
            {
                DropDownList.Add(new CommDept
                {
                    CommDeptID = Convert.ToInt32(rdr.GetString(0)),
                    DeptText = rdr.GetString(1)
                });
            }
        }
    }

    var adjList = new CommDept();
    adjList.DropDownList = new SelectList(DropDownList, "CommDeptID", "DeptText");
}

Index.cshtml

    <select class="form-control rounded" asp-items="Model.DropDownList"></select>

Answer 1

错误提示，请尝试使用显式类型强制转换：

DropDownList.Add((SelectListItem)new CommDept
{
    CommDeptID = Convert.ToInt32(rdr.GetString(0)),
    DeptText = rdr.GetString(1)
});

如果这不起作用，则您必须在CommDept类上write a custom Type converter，或者直接使用new SelectListItem { Value = ..., Text = ... }。

带有ADO.Net的.Net Core Razor页面DropDownList

1 个答案: