CODEWITHSUNDEEP
c#linq
Jochem
Jochem

Reputation: 13

Fetching 1 record based on the name of the logged in User and show these values in txt boxes (c#)

I Want to fetch 1 record based on the name of the logged in User and show these values in txt boxes (c#) I am a bit stuck on how to handle this, any help would be welcome.

Currently I am trying to fetch it using LINQ:

DAL.VindjekindjeDataContext dc = new DAL.VindjekindjeDataContext();

public object GetCompleteOuder(string p)
{
    //var query = (from TOUD in dc.TOUDs where TOUD.Ouderid == p select TOUD).Single();

    return (from TOUD in dc.TOUDs where TOUD.Voornaam.Equals(p) select TOUD ).First();

}

protected void Page_Load(object sender, EventArgs e)
{
    string naam = User.Identity.Name;

    object parent = new object();
    parent = Ouder.GetCompleteOuder(naam);


    Type typB = parent.GetType();
    NaamTxt.Text = (string)typB.GetField("Naam").GetValue(parent);

}

However I get the following error:

System.NullReferenceException: Object reference not set to an instance of an object.

Upvotes: 0

Views: 51

Answers (3)

Jochem
Jochem

Reputation: 13

Final working code:

DAL.VindjekindjeDataContext dc = new DAL.VindjekindjeDataContext();



public bool GetCompleteOuder(out DAL.TOUD  user, string p)
{
    user = new DAL.TOUD();

    try
    {
        dc.TOUDs.SingleOrDefault(t => t.Voornaam == p);
        user = (from TOUD in dc.TOUDs where TOUD.Voornaam.Equals(p) select TOUD).Single();
        return true;
    }
    catch
    {
        return false;
    }
}

//page load behind aspx page

OuderDAL Ouder = new OuderDAL();
protected void Page_Load(object sender, EventArgs e)
{
    string naam = User.Identity.Name;

    DAL.TOUD user; 

if(Ouder.GetCompleteOuder(out user, naam))
{

    /*vullen van de velden met de gegevens voor de ingelogde gebruiker*/
    NaamTxt.Text = user.Naam;

Upvotes: 0

Andy Evans
Andy Evans

Reputation: 7176

Perhaps something like this

public bool GetCompleteOuder(out TOUD user, string p)
{
    user = new TOUD();

    try
    {
        db.TOUDS.SingleOrDefault(t => t.Voornaam == p);
        return true;
    }
    catch
    {
        return false;
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    string naam = User.Identity.Name;
    TOUD user;
    if(GetCompleteOuder(out user, naam))
    {
        NaamTxt.Text = user.<fieldname>;
    }
    else
    {
        NaamTxt.Text = string.empty;
    }
}

Upvotes: 0

Patrick Hofman
Patrick Hofman

Reputation: 156948

There is just too much going wrong here.

  1. Your exception is possibly caused by a parent (ouder in Dutch) which has a null value for Voornaam)
  2. You instantiate an object parent which is useless since you overwrite it the next line.
  3. Your parent variable should be strongly typed. That will prevent you to need reflection to get the Naam property. This, by the way, is another possible source for your NullReferenceException.

Upvotes: 1

Related Questions