Entity Framework Returns NULL linked object C#

Question

I use Entity Framework in my program, and I have a problem when a record is being removable from the table, the table linked objects come NULL.

Instead of doing

waitTravel = db.WaitTravels 
               .Where(w => w.suggestTravelId == suggestTravelId &&
                           w.wantedTravelId == wantedTravelId)
               .First();

if (waitTravel.WantedTravels.statusTravelId != 1)

I should do that:

 if (db.WantedTravels.Where(w => w.id == waitTravel.wantedTravelId).First().statusTravelId != 1)

Know something to help me?

Do you mean why is waitTravel.WantedTravels null in your if condition? — MJK
– MJK, Commented Jun 13, 2016 at 13:37

Igor · Accepted Answer · 2016-06-13 13:34:01Z

1

I believe what you are asking is why is waitTravel.WantedTravels null in your if statement. That is because you are missing an include statement and you do not have lazy loading enabled.

See the EF documentation on Loading Related Entities for additional options on how you can accomplish this. The easiest, and IMO best way, is to explicitly use Include when you know you want to retrieve a related property/collection.

waitTravel = db.WaitTravels 
               .Where(w => w.suggestTravelId == suggestTravelId &&
                           w.wantedTravelId == wantedTravelId)
               .Include(w => w.WantedTravels) // added
               .First();

If this is not what you are asking then please clarify your question.

answered Jun 13, 2016 at 13:34

Igor

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2 Comments

R.H Over a year ago

There is a way to do this in a general way the entire program?

Igor Over a year ago

@R.H - You can enable lazy loading for the entire DbContext. See How to: Use Lazy Loading to Load Related Objects

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