EntitySQL -- Object reference not set to an instance of an object

Question

I am getting this error when I try to do an insert on a column that is a foreign key. Here is how I am assigning the value

var at = MvcApplication1.Entity.alttitles.Createalttitles(0, altTitleText);
        at.question.question_id = questionid;   //Error here
        at.userinfo.user_userid = _AuthorID;    //Error here
        context.AddToalttitles(at);
        res = context.SaveChanges();

When I made the question_id and the userid a foreign key I started getting this error. Is there a way to fix this?

marc_s · Accepted Answer · 2009-10-02 20:27:00Z

1

~~Most likely, the "question" is a referenced entity, right? Those are not included by default in your query - you'll need to specifically either include them in your first query~~

~~var at = MvcApplication1.Entity.alttitles .Createalttitles(0, altTitleText) .Include("question");~~

Is "question" a 1:1 or 1:n navigation property? In the 1:n case, you can check the "question" property directly:

if(!at.question.IsLoaded)
{
   at.question.Load();

   ....
}

In a 1:1 navigation property case, you probably have a "QuestionReference" property as well:

if(!at.QuestionReference.IsLoaded)
{
   at.QuestionReference.Load();

   ....
}

Marc

edited Oct 2, 2009 at 20:27

answered Oct 2, 2009 at 18:35

marc_s

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5 Comments

Craig Stuntz Over a year ago

Your examples are backwards. "Reference" is for 1:1.

marc_s Over a year ago

oops - thanks for pointing that out! Haven't been using it much lately (waiting for EF4), so my memory begins to slip :-)

user161433 Over a year ago

Createalttitles is a entity sql create function to insert new rows in the database. It does not have an Include option in intelisense

marc_s Over a year ago

ah okay, I didn't know if it was returning a IQueryable<T> interface or not; in that case, do any of the other ideas help? I am almost certain this is the root cause of the problem - the "question" property is not being populated automatically (since EF does not do that)

user161433 Over a year ago

OK..No problem..I will try this as soon as I get home..thank you

Gregoire · Accepted Answer · 2009-10-02 18:29:26Z

0

Check if at is not null before assigning its properties?

answered Oct 2, 2009 at 18:29

Gregoire

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