Question

I have the following code:

using (var db = new IntDB())
{
    var subscription =
        (from s in db.Subscription
         where s.SubsciptionId == subscriptionId
         select s).FirstOrDefault();
    if (subscription != null)
    {
        db.DeleteObject(subscription);
        db.SaveChanges();

        EntityKeyMember articleId = (EntityKeyMember)subscription.ArticleReference
                                 .EntityKey.EntityKeyValues.GetValue(0);
        var article = (from a in db.Article
                       where a.ArticleId == (int)articleId.Value
                       select a).FirstOrDefault();
        if (!String.IsNullOrEmpty(article.WebUrl) && article.WebUrl.Equals(@"/ExploderLists"))
        {
            var lstAppIntrfc = new ListAppInterface();
            // the articleId is stored in the entity key here, the article object hasn't been instanicated
            // so it's easier to just get it from the EntityKey.                            
            lstAppIntrfc.RemoveEmailFromListByArticleID((int)articleId.Value, subscription.EmailAddress);
        }
    }
}

and here’s my question. After I load the Subscription object with the LINQ code, I find that the Article property of the subscription instance is NULL! I can find the entityKey for the article in the subscription instance, but I have to then run LINQ to load the article instance that I need for the final IF statement there.

Have I just gone totally off the reservation here and I am not understanding how to use the entity objects or is this the only way to do this?

Answer 1

Use the Include method to eager load the Article with the Subscription.

using (var db = new IntDB())
{
    var subscription = db.Subscription.Include("Article")
          .Where(s => s.SubsciptionId == subscriptionId).FirstOrDefault();
    if (subscription != null)
    {
        var article = subscription.Article;
        db.DeleteObject(subscription);
        db.SaveChanges();

        if (!String.IsNullOrEmpty(article.WebUrl) && article.WebUrl.Equals(@"/ExploderLists"))
        {
            var lstAppIntrfc = new ListAppInterface();
            // the articleId is stored in the entity key here, the article object hasn't been instanicated
            // so it's easier to just get it from the EntityKey.                            
            lstAppIntrfc.RemoveEmailFromListByArticleID((int)articleId.Value, subscription.EmailAddress);
        }
    }
}