Question

这是我的代码。我想将列表保存在会话变量中以便以后进行身份验证（它是用户有权访问的对象列表....）我收到一条错误消息，说明它无法将System.Collections.Generic.List转换为'System。 collections.Generic.List。帮助

    protected void Session_Start(object sender, EventArgs e)
    {
        string strUserName = User.Identity.Name;
        string strShortUserName = strUserName.Replace("WINNTDOM\\", string.Empty).ToUpper();
        System.Web.HttpContext.Current.Session["strShortUserName"] = strShortUserName;
        System.Web.HttpContext.Current.Session["strUserName"] = strUserName;
        List<string> authorizedObjects = new List<string>();
        using (CPASEntities ctx = new CPASEntities())
        {
            var w = (from t in ctx.tblUsers
                     where (t.UserPassword == strUserName)
                     select t).FirstOrDefault();
            if (!(w==null))
            {
                authorizedObjects = (from t in ctx.qryUserObjectAuthorization
                                         where (t.UserPassword == strUserName)
                                         select new {  n = t.ObjectName }).ToList();

            }
        }
    }

Answer 1

authorizedObjects是List<string>，但您尝试将其用作匿名类型列表：

List<string> authorizedObjects = new List<string>();

（...）

authorizedObjects = (from t in ctx.qryUserObjectAuthorization
                     where (t.UserPassword == strUserName)
                     select new {  n = t.ObjectName, i = t.ObjectID }).ToList()

将您的查询更改为：

authorizedObjects = (from t in ctx.qryUserObjectAuthorization
                     where (t.UserPassword == strUserName)
                     select t.ObjectName).ToList()

Answer 2

您正在初始化List<string>对象，但填充了不同的对象。

List<string> authorizedObjects = new List<string>();

select new {  n = t.ObjectName, i = t.ObjectID } <--construct a class with these properties and initialize `List<WithNewClassName>`

Answer 3

要将其生成为字符串列表，请使用

authorizedObjects = (from t in ctx.qryUserObjectAuthorization
                     where (t.UserPassword == strUserName)
                     select t.ObjectName).ToList();

将Linq查询转换为列表时出错

3 个答案: