在SQL查询中获取User.Identity.GetUserId

Question

Trying to get currently logged in users userid and use it in an SQL query from behindcode to fill a gridview but its not working any ideas what I'm doing wrong. I keep getting a null value error. Also I'm trying to only use the Microsoft.AspNet.Identity if thats even possible

pageload

if (!IsPostBack)
    {
        SqlDataSource SqlDataSource1 = new SqlDataSource();
        SqlDataSource1.ID = "SqlDataSource1";
        this.Page.Controls.Add(SqlDataSource1);
        SqlDataSource1.InsertParameters["luser"].DefaultValue = User.Identity.GetUserId();
        SqlDataSource1.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
        SqlDataSource1.SelectCommand = "SELECT top 3 UserId, Friending from Friendreq Where Friending = @luser";
        GridView1.DataSource = SqlDataSource1;
        GridView1.DataBind();
    }

UPDATE:

I was able to get the results that i wanted by adding the requested directly into the SQL query. Is there any reason that i should not add it that what

 SqlDataSource SqlDataSource1 = new SqlDataSource();
    SqlDataSource1.ID = "SqlDataSource1";
    this.Page.Controls.Add(SqlDataSource1);

    SqlDataSource1.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
    SqlDataSource1.SelectCommand = "SELECT top 3 UserId, Friending from Friendreq Where Friending = '"+User.Identity.GetUserId()+"'";
    GridView1.DataSource = SqlDataSource1;
    GridView1.DataBind();

Solution = Friending = '"+User.Identity.GetUserId()+"'";

Answer 1

If are trying to get user identity from HttpContext then try following code instead. Identity store username/id (based on your logic) in Name property.

Also the object reference error is coming because you have not added "luser" in InsertParameter, but trying to set default value for it. I have added this SqlDataSource1.InsertParameters.Add(new Parameter("luser")); to make sure it have the parameter, before you use it

if (!IsPostBack)
    {
        SqlDataSource SqlDataSource1 = new SqlDataSource();
        SqlDataSource1.ID = "SqlDataSource1";
        this.Page.Controls.Add(SqlDataSource1);
        SqlDataSource1.InsertParameters.Add(new Parameter("luser"));
        SqlDataSource1.InsertParameters["luser"].DefaultValue = HttpContext.Current.User.Identity.IsAuthenticated ? HttpContext.Current.User.Identity.Name : String.Empty;
        SqlDataSource1.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
        SqlDataSource1.SelectCommand = "SELECT top 3 UserId, Friending from Friendreq Where Friending = @luser";
        GridView1.DataSource = SqlDataSource1;
        GridView1.DataBind();
    }